* [PATCH 1/9] x86/dumpstack: Remove code_bytes
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:18 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 2/9] x86/dumpstack: Unexport oops_begin() Borislav Petkov
` (7 subsequent siblings)
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
This was added by
86c418374223 ("[PATCH] i386: add option to show more code in oops reports")
long time ago but experience shows that 64 instruction bytes are plenty
when deciphering an oops. So get rid of it.
Removing it will simplify further enhancements to the opcodes dumping
machinery coming in the following patches.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
Documentation/admin-guide/kernel-parameters.txt | 5 -----
arch/x86/kernel/dumpstack.c | 27 ++++---------------------
2 files changed, 4 insertions(+), 28 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 11fc28ecdb6d..47aa554e41b7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -587,11 +587,6 @@
Sets the size of memory pool for coherent, atomic dma
allocations, by default set to 256K.
- code_bytes [X86] How many bytes of object code to print
- in an oops report.
- Range: 0 - 8192
- Default: 64
-
com20020= [HW,NET] ARCnet - COM20020 chipset
Format:
<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 18fa9d74c182..593db796374d 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -22,9 +22,10 @@
#include <asm/stacktrace.h>
#include <asm/unwind.h>
+#define OPCODE_BUFSIZE 64
+
int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
-static unsigned int code_bytes = 64;
static int die_counter;
bool in_task_stack(unsigned long *stack, struct task_struct *task,
@@ -356,26 +357,6 @@ void die(const char *str, struct pt_regs *regs, long err)
oops_end(flags, regs, sig);
}
-static int __init code_bytes_setup(char *s)
-{
- ssize_t ret;
- unsigned long val;
-
- if (!s)
- return -EINVAL;
-
- ret = kstrtoul(s, 0, &val);
- if (ret)
- return ret;
-
- code_bytes = val;
- if (code_bytes > 8192)
- code_bytes = 8192;
-
- return 1;
-}
-__setup("code_bytes=", code_bytes_setup);
-
void show_regs(struct pt_regs *regs)
{
bool all = true;
@@ -393,8 +374,8 @@ void show_regs(struct pt_regs *regs)
* time of the fault..
*/
if (!user_mode(regs)) {
- unsigned int code_prologue = code_bytes * 43 / 64;
- unsigned int code_len = code_bytes;
+ unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
+ unsigned int code_len = OPCODE_BUFSIZE;
unsigned char c;
u8 *ip;
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Remove code_bytes
2018-04-17 16:11 ` [PATCH 1/9] x86/dumpstack: Remove code_bytes Borislav Petkov
@ 2018-04-26 14:18 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:18 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, jpoimboe, mingo, peterz, luto, hpa, torvalds, bp, tglx
Commit-ID: 5d12f0424edf01ccd8abbcba1c7d45fe0b23c779
Gitweb: https://git.kernel.org/tip/5d12f0424edf01ccd8abbcba1c7d45fe0b23c779
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:16 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:25 +0200
x86/dumpstack: Remove code_bytes
This was added by
86c418374223 ("[PATCH] i386: add option to show more code in oops reports")
long time ago but experience shows that 64 instruction bytes are plenty
when deciphering an oops. So get rid of it.
Removing it will simplify further enhancements to the opcodes dumping
machinery coming in the following patches.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-2-bp@alien8.de
---
Documentation/admin-guide/kernel-parameters.txt | 5 -----
arch/x86/kernel/dumpstack.c | 27 ++++---------------------
2 files changed, 4 insertions(+), 28 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 11fc28ecdb6d..47aa554e41b7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -587,11 +587,6 @@
Sets the size of memory pool for coherent, atomic dma
allocations, by default set to 256K.
- code_bytes [X86] How many bytes of object code to print
- in an oops report.
- Range: 0 - 8192
- Default: 64
-
com20020= [HW,NET] ARCnet - COM20020 chipset
Format:
<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 18fa9d74c182..593db796374d 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -22,9 +22,10 @@
#include <asm/stacktrace.h>
#include <asm/unwind.h>
+#define OPCODE_BUFSIZE 64
+
int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
-static unsigned int code_bytes = 64;
static int die_counter;
bool in_task_stack(unsigned long *stack, struct task_struct *task,
@@ -356,26 +357,6 @@ void die(const char *str, struct pt_regs *regs, long err)
oops_end(flags, regs, sig);
}
-static int __init code_bytes_setup(char *s)
-{
- ssize_t ret;
- unsigned long val;
-
- if (!s)
- return -EINVAL;
-
- ret = kstrtoul(s, 0, &val);
- if (ret)
- return ret;
-
- code_bytes = val;
- if (code_bytes > 8192)
- code_bytes = 8192;
-
- return 1;
-}
-__setup("code_bytes=", code_bytes_setup);
-
void show_regs(struct pt_regs *regs)
{
bool all = true;
@@ -393,8 +374,8 @@ void show_regs(struct pt_regs *regs)
* time of the fault..
*/
if (!user_mode(regs)) {
- unsigned int code_prologue = code_bytes * 43 / 64;
- unsigned int code_len = code_bytes;
+ unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
+ unsigned int code_len = OPCODE_BUFSIZE;
unsigned char c;
u8 *ip;
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 2/9] x86/dumpstack: Unexport oops_begin()
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
2018-04-17 16:11 ` [PATCH 1/9] x86/dumpstack: Remove code_bytes Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:19 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 3/9] x86/dumpstack: Carve out Code: dumping into a function Borislav Petkov
` (6 subsequent siblings)
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
The only user outside of arch/ is not a module since
86cd47334b00 ("ACPI, APEI, GHES, Prevent GHES to be built as module")
No functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/dumpstack.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 593db796374d..579455c2b91e 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -268,7 +268,6 @@ unsigned long oops_begin(void)
bust_spinlocks(1);
return flags;
}
-EXPORT_SYMBOL_GPL(oops_begin);
NOKPROBE_SYMBOL(oops_begin);
void __noreturn rewind_stack_do_exit(int signr);
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Unexport oops_begin()
2018-04-17 16:11 ` [PATCH 2/9] x86/dumpstack: Unexport oops_begin() Borislav Petkov
@ 2018-04-26 14:19 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:19 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, mingo, tglx, luto, peterz, jpoimboe, hpa, torvalds, bp
Commit-ID: 5df61707f0bdf8dce714a14806740e6abf2114c7
Gitweb: https://git.kernel.org/tip/5df61707f0bdf8dce714a14806740e6abf2114c7
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:17 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:26 +0200
x86/dumpstack: Unexport oops_begin()
The only user outside of arch/ is not a module since
86cd47334b00 ("ACPI, APEI, GHES, Prevent GHES to be built as module")
No functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-3-bp@alien8.de
---
arch/x86/kernel/dumpstack.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 593db796374d..579455c2b91e 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -268,7 +268,6 @@ unsigned long oops_begin(void)
bust_spinlocks(1);
return flags;
}
-EXPORT_SYMBOL_GPL(oops_begin);
NOKPROBE_SYMBOL(oops_begin);
void __noreturn rewind_stack_do_exit(int signr);
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 3/9] x86/dumpstack: Carve out Code: dumping into a function
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
2018-04-17 16:11 ` [PATCH 1/9] x86/dumpstack: Remove code_bytes Borislav Petkov
2018-04-17 16:11 ` [PATCH 2/9] x86/dumpstack: Unexport oops_begin() Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:19 ` [tip:x86/cleanups] x86/dumpstack: Carve out code-dumping " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 4/9] x86/dumpstack: Improve opcodes dumping in the Code: section Borislav Petkov
` (5 subsequent siblings)
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
No functionality change, carve it out into a separate function for later
changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/dumpstack.c | 57 ++++++++++++++++++++++++---------------------
1 file changed, 30 insertions(+), 27 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 579455c2b91e..eb9d6c00a52f 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -70,6 +70,35 @@ static void printk_stack_address(unsigned long address, int reliable,
printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
}
+static void show_opcodes(u8 *rip)
+{
+ unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
+ unsigned int code_len = OPCODE_BUFSIZE;
+ unsigned char c;
+ u8 *ip;
+ int i;
+
+ printk(KERN_DEFAULT "Code: ");
+
+ ip = (u8 *)rip - code_prologue;
+ if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
+ /* try starting at IP */
+ ip = (u8 *)rip;
+ code_len = code_len - code_prologue + 1;
+ }
+ for (i = 0; i < code_len; i++, ip++) {
+ if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
+ pr_cont(" Bad RIP value.");
+ break;
+ }
+ if (ip == (u8 *)rip)
+ pr_cont("<%02x> ", c);
+ else
+ pr_cont("%02x ", c);
+ }
+ pr_cont("\n");
+}
+
void show_iret_regs(struct pt_regs *regs)
{
printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
@@ -359,7 +388,6 @@ void die(const char *str, struct pt_regs *regs, long err)
void show_regs(struct pt_regs *regs)
{
bool all = true;
- int i;
show_regs_print_info(KERN_DEFAULT);
@@ -373,32 +401,7 @@ void show_regs(struct pt_regs *regs)
* time of the fault..
*/
if (!user_mode(regs)) {
- unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
- unsigned int code_len = OPCODE_BUFSIZE;
- unsigned char c;
- u8 *ip;
-
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
-
- printk(KERN_DEFAULT "Code: ");
-
- ip = (u8 *)regs->ip - code_prologue;
- if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
- /* try starting at IP */
- ip = (u8 *)regs->ip;
- code_len = code_len - code_prologue + 1;
- }
- for (i = 0; i < code_len; i++, ip++) {
- if (ip < (u8 *)PAGE_OFFSET ||
- probe_kernel_address(ip, c)) {
- pr_cont(" Bad RIP value.");
- break;
- }
- if (ip == (u8 *)regs->ip)
- pr_cont("<%02x> ", c);
- else
- pr_cont("%02x ", c);
- }
+ show_opcodes((u8 *)regs->ip);
}
- pr_cont("\n");
}
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Carve out code-dumping into a function
2018-04-17 16:11 ` [PATCH 3/9] x86/dumpstack: Carve out Code: dumping into a function Borislav Petkov
@ 2018-04-26 14:19 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:19 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, bp, hpa, linux-kernel, jpoimboe, mingo, peterz, luto, torvalds
Commit-ID: f0a1d7c11c3ebe2f601b448d13e7fbc3a0364a03
Gitweb: https://git.kernel.org/tip/f0a1d7c11c3ebe2f601b448d13e7fbc3a0364a03
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:18 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:26 +0200
x86/dumpstack: Carve out code-dumping into a function
No functionality change, carve it out into a separate function for later
changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-4-bp@alien8.de
---
arch/x86/kernel/dumpstack.c | 57 ++++++++++++++++++++++++---------------------
1 file changed, 30 insertions(+), 27 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 579455c2b91e..eb9d6c00a52f 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -70,6 +70,35 @@ static void printk_stack_address(unsigned long address, int reliable,
printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
}
+static void show_opcodes(u8 *rip)
+{
+ unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
+ unsigned int code_len = OPCODE_BUFSIZE;
+ unsigned char c;
+ u8 *ip;
+ int i;
+
+ printk(KERN_DEFAULT "Code: ");
+
+ ip = (u8 *)rip - code_prologue;
+ if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
+ /* try starting at IP */
+ ip = (u8 *)rip;
+ code_len = code_len - code_prologue + 1;
+ }
+ for (i = 0; i < code_len; i++, ip++) {
+ if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
+ pr_cont(" Bad RIP value.");
+ break;
+ }
+ if (ip == (u8 *)rip)
+ pr_cont("<%02x> ", c);
+ else
+ pr_cont("%02x ", c);
+ }
+ pr_cont("\n");
+}
+
void show_iret_regs(struct pt_regs *regs)
{
printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
@@ -359,7 +388,6 @@ void die(const char *str, struct pt_regs *regs, long err)
void show_regs(struct pt_regs *regs)
{
bool all = true;
- int i;
show_regs_print_info(KERN_DEFAULT);
@@ -373,32 +401,7 @@ void show_regs(struct pt_regs *regs)
* time of the fault..
*/
if (!user_mode(regs)) {
- unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
- unsigned int code_len = OPCODE_BUFSIZE;
- unsigned char c;
- u8 *ip;
-
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
-
- printk(KERN_DEFAULT "Code: ");
-
- ip = (u8 *)regs->ip - code_prologue;
- if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
- /* try starting at IP */
- ip = (u8 *)regs->ip;
- code_len = code_len - code_prologue + 1;
- }
- for (i = 0; i < code_len; i++, ip++) {
- if (ip < (u8 *)PAGE_OFFSET ||
- probe_kernel_address(ip, c)) {
- pr_cont(" Bad RIP value.");
- break;
- }
- if (ip == (u8 *)regs->ip)
- pr_cont("<%02x> ", c);
- else
- pr_cont("%02x ", c);
- }
+ show_opcodes((u8 *)regs->ip);
}
- pr_cont("\n");
}
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 4/9] x86/dumpstack: Improve opcodes dumping in the Code: section
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
` (2 preceding siblings ...)
2018-04-17 16:11 ` [PATCH 3/9] x86/dumpstack: Carve out Code: dumping into a function Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:20 ` [tip:x86/cleanups] x86/dumpstack: Improve opcodes dumping in the code section tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 5/9] x86/dumpstack: Add loglevel argument to show_opcodes() Borislav Petkov
` (4 subsequent siblings)
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
The code used to iterate byte-by-byte over the bytes around RIP and that
is expensive: disabling pagefaults around it, copy_from_user, etc...
Make it read the whole buffer of OPCODE_BUFSIZE size in one go. Use a
statically allocated 64 bytes buffer so that concurrent show_opcodes()
do not interleave in the output even though in the majority of the cases
we sync on die_lock. Except the #PF path which doesn't...
Also, do the PAGE_OFFSET check outside of the function because latter
will be reused in other context.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/dumpstack.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index eb9d6c00a52f..1d6698b54527 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -72,29 +72,24 @@ static void printk_stack_address(unsigned long address, int reliable,
static void show_opcodes(u8 *rip)
{
- unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
- unsigned int code_len = OPCODE_BUFSIZE;
- unsigned char c;
+ unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
+ u8 opcodes[OPCODE_BUFSIZE];
u8 *ip;
int i;
printk(KERN_DEFAULT "Code: ");
ip = (u8 *)rip - code_prologue;
- if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
- /* try starting at IP */
- ip = (u8 *)rip;
- code_len = code_len - code_prologue + 1;
+ if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
+ pr_cont("Bad RIP value.\n");
+ return;
}
- for (i = 0; i < code_len; i++, ip++) {
- if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
- pr_cont(" Bad RIP value.");
- break;
- }
- if (ip == (u8 *)rip)
- pr_cont("<%02x> ", c);
+
+ for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) {
+ if (ip == rip)
+ pr_cont("<%02x> ", opcodes[i]);
else
- pr_cont("%02x ", c);
+ pr_cont("%02x ", opcodes[i]);
}
pr_cont("\n");
}
@@ -402,6 +397,10 @@ void show_regs(struct pt_regs *regs)
*/
if (!user_mode(regs)) {
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
- show_opcodes((u8 *)regs->ip);
+
+ if (regs->ip < PAGE_OFFSET)
+ printk(KERN_DEFAULT "Code: Bad RIP value.\n");
+ else
+ show_opcodes((u8 *)regs->ip);
}
}
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Improve opcodes dumping in the code section
2018-04-17 16:11 ` [PATCH 4/9] x86/dumpstack: Improve opcodes dumping in the Code: section Borislav Petkov
@ 2018-04-26 14:20 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:20 UTC (permalink / raw)
To: linux-tip-commits
Cc: mingo, linux-kernel, luto, hpa, jpoimboe, peterz, bp, tglx, torvalds
Commit-ID: 9e4a90fd34445df64a13d136676a31a4dd22aea3
Gitweb: https://git.kernel.org/tip/9e4a90fd34445df64a13d136676a31a4dd22aea3
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:19 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:26 +0200
x86/dumpstack: Improve opcodes dumping in the code section
The code used to iterate byte-by-byte over the bytes around RIP and that
is expensive: disabling pagefaults around it, copy_from_user, etc...
Make it read the whole buffer of OPCODE_BUFSIZE size in one go. Use a
statically allocated 64 bytes buffer so that concurrent show_opcodes()
do not interleave in the output even though in the majority of the cases
it's serialized via die_lock. Except the #PF path which doesn't...
Also, do the PAGE_OFFSET check outside of the function because latter
will be reused in other context.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-5-bp@alien8.de
---
arch/x86/kernel/dumpstack.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index eb9d6c00a52f..1d6698b54527 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -72,29 +72,24 @@ static void printk_stack_address(unsigned long address, int reliable,
static void show_opcodes(u8 *rip)
{
- unsigned int code_prologue = OPCODE_BUFSIZE * 43 / 64;
- unsigned int code_len = OPCODE_BUFSIZE;
- unsigned char c;
+ unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
+ u8 opcodes[OPCODE_BUFSIZE];
u8 *ip;
int i;
printk(KERN_DEFAULT "Code: ");
ip = (u8 *)rip - code_prologue;
- if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
- /* try starting at IP */
- ip = (u8 *)rip;
- code_len = code_len - code_prologue + 1;
+ if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
+ pr_cont("Bad RIP value.\n");
+ return;
}
- for (i = 0; i < code_len; i++, ip++) {
- if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
- pr_cont(" Bad RIP value.");
- break;
- }
- if (ip == (u8 *)rip)
- pr_cont("<%02x> ", c);
+
+ for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) {
+ if (ip == rip)
+ pr_cont("<%02x> ", opcodes[i]);
else
- pr_cont("%02x ", c);
+ pr_cont("%02x ", opcodes[i]);
}
pr_cont("\n");
}
@@ -402,6 +397,10 @@ void show_regs(struct pt_regs *regs)
*/
if (!user_mode(regs)) {
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
- show_opcodes((u8 *)regs->ip);
+
+ if (regs->ip < PAGE_OFFSET)
+ printk(KERN_DEFAULT "Code: Bad RIP value.\n");
+ else
+ show_opcodes((u8 *)regs->ip);
}
}
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 5/9] x86/dumpstack: Add loglevel argument to show_opcodes()
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
` (3 preceding siblings ...)
2018-04-17 16:11 ` [PATCH 4/9] x86/dumpstack: Improve opcodes dumping in the Code: section Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:20 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 6/9] x86/fault: Dump user opcode bytes on fatal faults Borislav Petkov
` (3 subsequent siblings)
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
Will be used in the next patch.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/include/asm/stacktrace.h | 1 +
arch/x86/kernel/dumpstack.c | 6 +++---
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 133d9425fced..0630eeb18bbc 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -111,4 +111,5 @@ static inline unsigned long caller_frame_pointer(void)
return (unsigned long)frame;
}
+void show_opcodes(u8 *rip, const char *loglvl);
#endif /* _ASM_X86_STACKTRACE_H */
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 1d6698b54527..1592d0c3ebb5 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -70,14 +70,14 @@ static void printk_stack_address(unsigned long address, int reliable,
printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
}
-static void show_opcodes(u8 *rip)
+void show_opcodes(u8 *rip, const char *loglvl)
{
unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
u8 opcodes[OPCODE_BUFSIZE];
u8 *ip;
int i;
- printk(KERN_DEFAULT "Code: ");
+ printk("%sCode: ", loglvl);
ip = (u8 *)rip - code_prologue;
if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
@@ -401,6 +401,6 @@ void show_regs(struct pt_regs *regs)
if (regs->ip < PAGE_OFFSET)
printk(KERN_DEFAULT "Code: Bad RIP value.\n");
else
- show_opcodes((u8 *)regs->ip);
+ show_opcodes((u8 *)regs->ip, KERN_DEFAULT);
}
}
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Add loglevel argument to show_opcodes()
2018-04-17 16:11 ` [PATCH 5/9] x86/dumpstack: Add loglevel argument to show_opcodes() Borislav Petkov
@ 2018-04-26 14:20 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:20 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, hpa, torvalds, peterz, bp, mingo, linux-kernel, luto, jpoimboe
Commit-ID: e8b6f984516b1fcb0ccf4469ca42777c9c2dc76d
Gitweb: https://git.kernel.org/tip/e8b6f984516b1fcb0ccf4469ca42777c9c2dc76d
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:20 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:26 +0200
x86/dumpstack: Add loglevel argument to show_opcodes()
Will be used in the next patch.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-6-bp@alien8.de
---
arch/x86/include/asm/stacktrace.h | 1 +
arch/x86/kernel/dumpstack.c | 6 +++---
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 133d9425fced..0630eeb18bbc 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -111,4 +111,5 @@ static inline unsigned long caller_frame_pointer(void)
return (unsigned long)frame;
}
+void show_opcodes(u8 *rip, const char *loglvl);
#endif /* _ASM_X86_STACKTRACE_H */
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 1d6698b54527..1592d0c3ebb5 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -70,14 +70,14 @@ static void printk_stack_address(unsigned long address, int reliable,
printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
}
-static void show_opcodes(u8 *rip)
+void show_opcodes(u8 *rip, const char *loglvl)
{
unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
u8 opcodes[OPCODE_BUFSIZE];
u8 *ip;
int i;
- printk(KERN_DEFAULT "Code: ");
+ printk("%sCode: ", loglvl);
ip = (u8 *)rip - code_prologue;
if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
@@ -401,6 +401,6 @@ void show_regs(struct pt_regs *regs)
if (regs->ip < PAGE_OFFSET)
printk(KERN_DEFAULT "Code: Bad RIP value.\n");
else
- show_opcodes((u8 *)regs->ip);
+ show_opcodes((u8 *)regs->ip, KERN_DEFAULT);
}
}
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 6/9] x86/fault: Dump user opcode bytes on fatal faults
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
` (4 preceding siblings ...)
2018-04-17 16:11 ` [PATCH 5/9] x86/dumpstack: Add loglevel argument to show_opcodes() Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:21 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 7/9] x86/dumpstack: Add a show_ip() function Borislav Petkov
` (2 subsequent siblings)
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
Sometimes it is useful to see which user opcode bytes RIP points to
when a fault happens: be it to rule out RIP corruption, to dump info
early during boot, when doing core dumps is impossible due to not having
writable fs yet.
Sometimes it is useful if debugging an issue and one doesn't have access
to the executable which caused the fault in order to disassemble it.
That last aspect might have some security implications so
show_unhandled_signals could be revisited for that or a new config
option added.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/mm/fault.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 73bd8c95ac71..a3fd94eff04d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -828,6 +828,8 @@ static inline void
show_signal_msg(struct pt_regs *regs, unsigned long error_code,
unsigned long address, struct task_struct *tsk)
{
+ const char *loglvl = task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG;
+
if (!unhandled_signal(tsk, SIGSEGV))
return;
@@ -835,13 +837,14 @@ show_signal_msg(struct pt_regs *regs, unsigned long error_code,
return;
printk("%s%s[%d]: segfault at %lx ip %px sp %px error %lx",
- task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
- tsk->comm, task_pid_nr(tsk), address,
+ loglvl, tsk->comm, task_pid_nr(tsk), address,
(void *)regs->ip, (void *)regs->sp, error_code);
print_vma_addr(KERN_CONT " in ", regs->ip);
printk(KERN_CONT "\n");
+
+ show_opcodes((u8 *)regs->ip, loglvl);
}
static void
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/fault: Dump user opcode bytes on fatal faults
2018-04-17 16:11 ` [PATCH 6/9] x86/fault: Dump user opcode bytes on fatal faults Borislav Petkov
@ 2018-04-26 14:21 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:21 UTC (permalink / raw)
To: linux-tip-commits
Cc: jpoimboe, bp, torvalds, mingo, tglx, linux-kernel, luto, peterz, hpa
Commit-ID: ba54d856a9d8a9c56b87e20c88602b7e3cb568fb
Gitweb: https://git.kernel.org/tip/ba54d856a9d8a9c56b87e20c88602b7e3cb568fb
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:21 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:27 +0200
x86/fault: Dump user opcode bytes on fatal faults
Sometimes it is useful to see which user opcode bytes RIP points to
when a fault happens: be it to rule out RIP corruption, to dump info
early during boot, when doing core dumps is impossible due to not having
a writable filesystem yet.
Sometimes it is useful if debugging an issue and one doesn't have access
to the executable which caused the fault in order to disassemble it.
That last aspect might have some security implications so
show_unhandled_signals could be revisited for that or a new config option
added.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-7-bp@alien8.de
---
arch/x86/mm/fault.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 73bd8c95ac71..a3fd94eff04d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -828,6 +828,8 @@ static inline void
show_signal_msg(struct pt_regs *regs, unsigned long error_code,
unsigned long address, struct task_struct *tsk)
{
+ const char *loglvl = task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG;
+
if (!unhandled_signal(tsk, SIGSEGV))
return;
@@ -835,13 +837,14 @@ show_signal_msg(struct pt_regs *regs, unsigned long error_code,
return;
printk("%s%s[%d]: segfault at %lx ip %px sp %px error %lx",
- task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
- tsk->comm, task_pid_nr(tsk), address,
+ loglvl, tsk->comm, task_pid_nr(tsk), address,
(void *)regs->ip, (void *)regs->sp, error_code);
print_vma_addr(KERN_CONT " in ", regs->ip);
printk(KERN_CONT "\n");
+
+ show_opcodes((u8 *)regs->ip, loglvl);
}
static void
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 7/9] x86/dumpstack: Add a show_ip() function
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
` (5 preceding siblings ...)
2018-04-17 16:11 ` [PATCH 6/9] x86/fault: Dump user opcode bytes on fatal faults Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:21 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary Borislav Petkov
2018-04-17 16:11 ` [PATCH 9/9] x86/dumpstack: Explain the reasoning for the prologue and buffer size Borislav Petkov
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
... which shows the Instruction Pointer along with the insn bytes around
it. Use it whenever we print rIP. Drop the rIP < PAGE_OFFSET check since
our probe_kernel_read() can handle any address properly.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/include/asm/stacktrace.h | 1 +
arch/x86/kernel/dumpstack.c | 23 +++++++++++++----------
arch/x86/kernel/process_32.c | 8 +++-----
3 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 0630eeb18bbc..b6dc698f992a 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -112,4 +112,5 @@ static inline unsigned long caller_frame_pointer(void)
}
void show_opcodes(u8 *rip, const char *loglvl);
+void show_ip(struct pt_regs *regs, const char *loglvl);
#endif /* _ASM_X86_STACKTRACE_H */
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 1592d0c3ebb5..82da808b5c36 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -94,9 +94,19 @@ void show_opcodes(u8 *rip, const char *loglvl)
pr_cont("\n");
}
+void show_ip(struct pt_regs *regs, const char *loglvl)
+{
+#ifdef CONFIG_X86_32
+ printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
+#else
+ printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
+#endif
+ show_opcodes((u8 *)regs->ip, loglvl);
+}
+
void show_iret_regs(struct pt_regs *regs)
{
- printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
+ show_ip(regs, KERN_DEFAULT);
printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
regs->sp, regs->flags);
}
@@ -392,15 +402,8 @@ void show_regs(struct pt_regs *regs)
__show_regs(regs, all);
/*
- * When in-kernel, we also print out the stack and code at the
- * time of the fault..
+ * When in-kernel, we also print out the stack at the time of the fault..
*/
- if (!user_mode(regs)) {
+ if (!user_mode(regs))
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
-
- if (regs->ip < PAGE_OFFSET)
- printk(KERN_DEFAULT "Code: Bad RIP value.\n");
- else
- show_opcodes((u8 *)regs->ip, KERN_DEFAULT);
- }
}
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 5224c6099184..0ae659de21eb 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -76,16 +76,14 @@ void __show_regs(struct pt_regs *regs, int all)
savesegment(gs, gs);
}
- printk(KERN_DEFAULT "EIP: %pS\n", (void *)regs->ip);
- printk(KERN_DEFAULT "EFLAGS: %08lx CPU: %d\n", regs->flags,
- raw_smp_processor_id());
+ show_ip(regs, KERN_DEFAULT);
printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
regs->si, regs->di, regs->bp, sp);
- printk(KERN_DEFAULT " DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
- (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
+ printk(KERN_DEFAULT "DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n",
+ (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss, regs->flags);
if (!all)
return;
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Add a show_ip() function
2018-04-17 16:11 ` [PATCH 7/9] x86/dumpstack: Add a show_ip() function Borislav Petkov
@ 2018-04-26 14:21 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:21 UTC (permalink / raw)
To: linux-tip-commits
Cc: mingo, peterz, tglx, bp, hpa, jpoimboe, luto, torvalds, linux-kernel
Commit-ID: 7cccf0725cf7402514e09c52b089430005798b7f
Gitweb: https://git.kernel.org/tip/7cccf0725cf7402514e09c52b089430005798b7f
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:22 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:27 +0200
x86/dumpstack: Add a show_ip() function
... which shows the Instruction Pointer along with the insn bytes around
it. Use it whenever rIP is printed. Drop the rIP < PAGE_OFFSET check since
probe_kernel_read() can handle any address properly.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-8-bp@alien8.de
---
arch/x86/include/asm/stacktrace.h | 1 +
arch/x86/kernel/dumpstack.c | 23 +++++++++++++----------
arch/x86/kernel/process_32.c | 8 +++-----
3 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 0630eeb18bbc..b6dc698f992a 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -112,4 +112,5 @@ static inline unsigned long caller_frame_pointer(void)
}
void show_opcodes(u8 *rip, const char *loglvl);
+void show_ip(struct pt_regs *regs, const char *loglvl);
#endif /* _ASM_X86_STACKTRACE_H */
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 1592d0c3ebb5..82da808b5c36 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -94,9 +94,19 @@ void show_opcodes(u8 *rip, const char *loglvl)
pr_cont("\n");
}
+void show_ip(struct pt_regs *regs, const char *loglvl)
+{
+#ifdef CONFIG_X86_32
+ printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
+#else
+ printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
+#endif
+ show_opcodes((u8 *)regs->ip, loglvl);
+}
+
void show_iret_regs(struct pt_regs *regs)
{
- printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
+ show_ip(regs, KERN_DEFAULT);
printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
regs->sp, regs->flags);
}
@@ -392,15 +402,8 @@ void show_regs(struct pt_regs *regs)
__show_regs(regs, all);
/*
- * When in-kernel, we also print out the stack and code at the
- * time of the fault..
+ * When in-kernel, we also print out the stack at the time of the fault..
*/
- if (!user_mode(regs)) {
+ if (!user_mode(regs))
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
-
- if (regs->ip < PAGE_OFFSET)
- printk(KERN_DEFAULT "Code: Bad RIP value.\n");
- else
- show_opcodes((u8 *)regs->ip, KERN_DEFAULT);
- }
}
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 5224c6099184..0ae659de21eb 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -76,16 +76,14 @@ void __show_regs(struct pt_regs *regs, int all)
savesegment(gs, gs);
}
- printk(KERN_DEFAULT "EIP: %pS\n", (void *)regs->ip);
- printk(KERN_DEFAULT "EFLAGS: %08lx CPU: %d\n", regs->flags,
- raw_smp_processor_id());
+ show_ip(regs, KERN_DEFAULT);
printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
regs->si, regs->di, regs->bp, sp);
- printk(KERN_DEFAULT " DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
- (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
+ printk(KERN_DEFAULT "DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n",
+ (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss, regs->flags);
if (!all)
return;
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
` (6 preceding siblings ...)
2018-04-17 16:11 ` [PATCH 7/9] x86/dumpstack: Add a show_ip() function Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:22 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
2018-04-17 16:11 ` [PATCH 9/9] x86/dumpstack: Explain the reasoning for the prologue and buffer size Borislav Petkov
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
Save the regs set when we call __die() for the first time and print it
in oops_end().
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/dumpstack.c | 32 ++++++++++++--------------------
1 file changed, 12 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 82da808b5c36..ee344030fd0a 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -28,6 +28,8 @@ int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
static int die_counter;
+static struct pt_regs exec_summary_regs;
+
bool in_task_stack(unsigned long *stack, struct task_struct *task,
struct stack_info *info)
{
@@ -321,6 +323,9 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
raw_local_irq_restore(flags);
oops_exit();
+ /* Executive summary in case the oops scrolled away */
+ __show_regs(&exec_summary_regs, true);
+
if (!signr)
return;
if (in_interrupt())
@@ -339,10 +344,10 @@ NOKPROBE_SYMBOL(oops_end);
int __die(const char *str, struct pt_regs *regs, long err)
{
-#ifdef CONFIG_X86_32
- unsigned short ss;
- unsigned long sp;
-#endif
+ /* Save the regs of the first oops for the executive summary later. */
+ if (!die_counter)
+ exec_summary_regs = *regs;
+
printk(KERN_DEFAULT
"%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
@@ -352,26 +357,13 @@ int __die(const char *str, struct pt_regs *regs, long err)
IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
(boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
+ show_regs(regs);
+ print_modules();
+
if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
return 1;
- print_modules();
- show_regs(regs);
-#ifdef CONFIG_X86_32
- if (user_mode(regs)) {
- sp = regs->sp;
- ss = regs->ss;
- } else {
- sp = kernel_stack_pointer(regs);
- savesegment(ss, ss);
- }
- printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
- (void *)regs->ip, ss, sp);
-#else
- /* Executive summary in case the oops scrolled away */
- printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
-#endif
return 0;
}
NOKPROBE_SYMBOL(__die);
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Save first regs set for the executive summary
2018-04-17 16:11 ` [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary Borislav Petkov
@ 2018-04-26 14:22 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:22 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, luto, bp, hpa, mingo, jpoimboe, torvalds, peterz, linux-kernel
Commit-ID: 602bd705da334f214fc03db328dc37d2f1f33307
Gitweb: https://git.kernel.org/tip/602bd705da334f214fc03db328dc37d2f1f33307
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:23 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:28 +0200
x86/dumpstack: Save first regs set for the executive summary
Save the regs set when __die() is onvoked for the first time and print it
in oops_end().
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-9-bp@alien8.de
---
arch/x86/kernel/dumpstack.c | 32 ++++++++++++--------------------
1 file changed, 12 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 82da808b5c36..ee344030fd0a 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -28,6 +28,8 @@ int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
static int die_counter;
+static struct pt_regs exec_summary_regs;
+
bool in_task_stack(unsigned long *stack, struct task_struct *task,
struct stack_info *info)
{
@@ -321,6 +323,9 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
raw_local_irq_restore(flags);
oops_exit();
+ /* Executive summary in case the oops scrolled away */
+ __show_regs(&exec_summary_regs, true);
+
if (!signr)
return;
if (in_interrupt())
@@ -339,10 +344,10 @@ NOKPROBE_SYMBOL(oops_end);
int __die(const char *str, struct pt_regs *regs, long err)
{
-#ifdef CONFIG_X86_32
- unsigned short ss;
- unsigned long sp;
-#endif
+ /* Save the regs of the first oops for the executive summary later. */
+ if (!die_counter)
+ exec_summary_regs = *regs;
+
printk(KERN_DEFAULT
"%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
@@ -352,26 +357,13 @@ int __die(const char *str, struct pt_regs *regs, long err)
IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
(boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
+ show_regs(regs);
+ print_modules();
+
if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
return 1;
- print_modules();
- show_regs(regs);
-#ifdef CONFIG_X86_32
- if (user_mode(regs)) {
- sp = regs->sp;
- ss = regs->ss;
- } else {
- sp = kernel_stack_pointer(regs);
- savesegment(ss, ss);
- }
- printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
- (void *)regs->ip, ss, sp);
-#else
- /* Executive summary in case the oops scrolled away */
- printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
-#endif
return 0;
}
NOKPROBE_SYMBOL(__die);
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH 9/9] x86/dumpstack: Explain the reasoning for the prologue and buffer size
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
` (7 preceding siblings ...)
2018-04-17 16:11 ` [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary Borislav Petkov
@ 2018-04-17 16:11 ` Borislav Petkov
2018-04-26 14:22 ` [tip:x86/cleanups] " tip-bot for Borislav Petkov
8 siblings, 1 reply; 19+ messages in thread
From: Borislav Petkov @ 2018-04-17 16:11 UTC (permalink / raw)
To: X86 ML
Cc: Andy Lutomirski, Josh Poimboeuf, Linus Torvalds, Peter Zijlstra, LKML
From: Borislav Petkov <bp@suse.de>
The whole reasoning behind the amount of opcode bytes dumped and
prologue length isn't very clear so let's hold down some of the reasons
for why it is done the way it is.
Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/dumpstack.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index ee344030fd0a..666a284116ac 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -72,6 +72,25 @@ static void printk_stack_address(unsigned long address, int reliable,
printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
}
+/*
+ * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
+ *
+ * In case where we don't have the exact kernel image (which, if we did, we can
+ * simply disassemble and navigate to the RIP), the purpose of the bigger
+ * prologue is to have more context and to be able to correlate the code from
+ * the different toolchains better.
+ *
+ * In addition, it helps in recreating the register allocation of the failing
+ * kernel and thus make sense of the register dump.
+ *
+ * What is more, the additional complication of a variable length insn arch like
+ * x86 warrants having longer byte sequence before rIP so that the disassembler
+ * can "sync" up properly and find instruction boundaries when decoding the
+ * opcode bytes.
+ *
+ * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
+ * guesstimate in attempt to achieve all of the above.
+ */
void show_opcodes(u8 *rip, const char *loglvl)
{
unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
--
2.13.0
^ permalink raw reply [flat|nested] 19+ messages in thread* [tip:x86/cleanups] x86/dumpstack: Explain the reasoning for the prologue and buffer size
2018-04-17 16:11 ` [PATCH 9/9] x86/dumpstack: Explain the reasoning for the prologue and buffer size Borislav Petkov
@ 2018-04-26 14:22 ` tip-bot for Borislav Petkov
0 siblings, 0 replies; 19+ messages in thread
From: tip-bot for Borislav Petkov @ 2018-04-26 14:22 UTC (permalink / raw)
To: linux-tip-commits
Cc: jpoimboe, torvalds, peterz, tglx, hpa, mingo, luto, linux-kernel, bp
Commit-ID: 4dba072cd097f35fa8f77c49d909ada2b079a4c4
Gitweb: https://git.kernel.org/tip/4dba072cd097f35fa8f77c49d909ada2b079a4c4
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 17 Apr 2018 18:11:24 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 26 Apr 2018 16:15:28 +0200
x86/dumpstack: Explain the reasoning for the prologue and buffer size
The whole reasoning behind the amount of opcode bytes dumped and prologue
length isn't very clear so write down some of the reasons for why it is
done the way it is.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180417161124.5294-10-bp@alien8.de
---
arch/x86/kernel/dumpstack.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index ee344030fd0a..666a284116ac 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -72,6 +72,25 @@ static void printk_stack_address(unsigned long address, int reliable,
printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
}
+/*
+ * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
+ *
+ * In case where we don't have the exact kernel image (which, if we did, we can
+ * simply disassemble and navigate to the RIP), the purpose of the bigger
+ * prologue is to have more context and to be able to correlate the code from
+ * the different toolchains better.
+ *
+ * In addition, it helps in recreating the register allocation of the failing
+ * kernel and thus make sense of the register dump.
+ *
+ * What is more, the additional complication of a variable length insn arch like
+ * x86 warrants having longer byte sequence before rIP so that the disassembler
+ * can "sync" up properly and find instruction boundaries when decoding the
+ * opcode bytes.
+ *
+ * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
+ * guesstimate in attempt to achieve all of the above.
+ */
void show_opcodes(u8 *rip, const char *loglvl)
{
unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
^ permalink raw reply [flat|nested] 19+ messages in thread