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* [V2][PATCH] selftests/x86: Fix error: variably modified 'altstack_data' at file scope
@ 2021-08-23 13:56 Jun Miao
  2021-08-23 20:29 ` Shuah Khan
  2021-08-23 22:48 ` kernel test robot
  0 siblings, 2 replies; 3+ messages in thread
From: Jun Miao @ 2021-08-23 13:56 UTC (permalink / raw)
  To: shuah; +Cc: linux-kselftest, linux-kernel, jun.miao

Based on glibc 2.33 -> 2.34, there is one new feature:

NEWS for version 2.34
=====================
Major new features:
* Add _SC_MINSIGSTKSZ and _SC_SIGSTKSZ.  When _DYNAMIC_STACK_SIZE_SOURCE
  or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ are no longer
  constant on Linux.  MINSIGSTKSZ is redefined to sysconf(_SC_MINSIGSTKSZ)
  and SIGSTKSZ is redefined to sysconf (_SC_SIGSTKSZ).  This supports
  dynamic sized register sets for modern architectural features like
  Arm SVE.

Build error with the GNU C Library 2.34:
DEBUG:	| sigreturn.c:150:13: error: variably modified 'altstack_data' at file scope
| sigreturn.c:150:13: error: variably modified 'altstack_data' at file scope
DEBUG:	|   150 | static char altstack_data[SIGSTKSZ];
|   150 | static char altstack_data[SIGSTKSZ];
DEBUG:	|       |             ^~~~~~~~~~~~~

Signed-off-by: Jun Miao <jun.miao@windriver.com>
---
 tools/testing/selftests/x86/mov_ss_trap.c         | 4 ++--
 tools/testing/selftests/x86/sigreturn.c           | 7 +++----
 tools/testing/selftests/x86/single_step_syscall.c | 4 ++--
 tools/testing/selftests/x86/syscall_arg_fault.c   | 7 +++----
 4 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/x86/mov_ss_trap.c b/tools/testing/selftests/x86/mov_ss_trap.c
index 6da0ac3f0135..1ebf5f3f0fcf 100644
--- a/tools/testing/selftests/x86/mov_ss_trap.c
+++ b/tools/testing/selftests/x86/mov_ss_trap.c
@@ -47,7 +47,6 @@
 unsigned short ss;
 extern unsigned char breakpoint_insn[];
 sigjmp_buf jmpbuf;
-static unsigned char altstack_data[SIGSTKSZ];
 
 static void enable_watchpoint(void)
 {
@@ -250,7 +249,7 @@ int main()
 	if (sigsetjmp(jmpbuf, 1) == 0) {
 		printf("[RUN]\tMOV SS; SYSENTER\n");
 		stack_t stack = {
-			.ss_sp = altstack_data,
+			.ss_sp = malloc(sizeof(char) * SIGSTKSZ),
 			.ss_size = SIGSTKSZ,
 		};
 		if (sigaltstack(&stack, NULL) != 0)
@@ -282,5 +281,6 @@ int main()
 	}
 
 	printf("[OK]\tI aten't dead\n");
+	free(stack.ss_sp);
 	return 0;
 }
diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
index 57c4f67f16ef..5d7961a5f7f6 100644
--- a/tools/testing/selftests/x86/sigreturn.c
+++ b/tools/testing/selftests/x86/sigreturn.c
@@ -138,9 +138,6 @@ static unsigned short LDT3(int idx)
 	return (idx << 3) | 7;
 }
 
-/* Our sigaltstack scratch space. */
-static char altstack_data[SIGSTKSZ];
-
 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
 		       int flags)
 {
@@ -771,7 +768,8 @@ int main()
 	setup_ldt();
 
 	stack_t stack = {
-		.ss_sp = altstack_data,
+		/* Our sigaltstack scratch space. */
+		.ss_sp = malloc(sizeof(char) * SIGSTKSZ),
 		.ss_size = SIGSTKSZ,
 	};
 	if (sigaltstack(&stack, NULL) != 0)
@@ -872,5 +870,6 @@ int main()
 	total_nerrs += test_nonstrict_ss();
 #endif
 
+	free(stack.ss_sp);
 	return total_nerrs ? 1 : 0;
 }
diff --git a/tools/testing/selftests/x86/single_step_syscall.c b/tools/testing/selftests/x86/single_step_syscall.c
index 120ac741fe44..158b2bb1474c 100644
--- a/tools/testing/selftests/x86/single_step_syscall.c
+++ b/tools/testing/selftests/x86/single_step_syscall.c
@@ -57,7 +57,6 @@ static void clearhandler(int sig)
 
 static volatile sig_atomic_t sig_traps, sig_eflags;
 sigjmp_buf jmpbuf;
-static unsigned char altstack_data[SIGSTKSZ];
 
 #ifdef __x86_64__
 # define REG_IP REG_RIP
@@ -210,7 +209,7 @@ int main()
 		unsigned long nr = SYS_getpid;
 		printf("[RUN]\tSet TF and check SYSENTER\n");
 		stack_t stack = {
-			.ss_sp = altstack_data,
+			.ss_sp = malloc(sizeof(char) * SIGSTKSZ),
 			.ss_size = SIGSTKSZ,
 		};
 		if (sigaltstack(&stack, NULL) != 0)
@@ -228,6 +227,7 @@ int main()
 
 		/* We're unreachable here.  SYSENTER forgets RIP. */
 	}
+	free(stack.ss_sp);
 	clearhandler(SIGSEGV);
 	clearhandler(SIGILL);
 	if (!(sig_eflags & X86_EFLAGS_TF)) {
diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c
index bff474b5efc6..461fa41a4d02 100644
--- a/tools/testing/selftests/x86/syscall_arg_fault.c
+++ b/tools/testing/selftests/x86/syscall_arg_fault.c
@@ -17,9 +17,6 @@
 
 #include "helpers.h"
 
-/* Our sigaltstack scratch space. */
-static unsigned char altstack_data[SIGSTKSZ];
-
 static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
 		       int flags)
 {
@@ -104,7 +101,8 @@ static void sigill(int sig, siginfo_t *info, void *ctx_void)
 int main()
 {
 	stack_t stack = {
-		.ss_sp = altstack_data,
+		/* Our sigaltstack scratch space. */
+		.ss_sp = malloc(sizeof(char) * SIGSTKSZ),
 		.ss_size = SIGSTKSZ,
 	};
 	if (sigaltstack(&stack, NULL) != 0)
@@ -233,5 +231,6 @@ int main()
 	set_eflags(get_eflags() & ~X86_EFLAGS_TF);
 #endif
 
+	free(stack.ss_sp);
 	return 0;
 }
-- 
2.32.0


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [V2][PATCH] selftests/x86: Fix error: variably modified 'altstack_data' at file scope
  2021-08-23 13:56 [V2][PATCH] selftests/x86: Fix error: variably modified 'altstack_data' at file scope Jun Miao
@ 2021-08-23 20:29 ` Shuah Khan
  2021-08-23 22:48 ` kernel test robot
  1 sibling, 0 replies; 3+ messages in thread
From: Shuah Khan @ 2021-08-23 20:29 UTC (permalink / raw)
  To: Jun Miao, shuah; +Cc: linux-kselftest, linux-kernel, Shuah Khan

On 8/23/21 7:56 AM, Jun Miao wrote:
> Based on glibc 2.33 -> 2.34, there is one new feature:
> 
> NEWS for version 2.34
> =====================
> Major new features:
> * Add _SC_MINSIGSTKSZ and _SC_SIGSTKSZ.  When _DYNAMIC_STACK_SIZE_SOURCE
>    or _GNU_SOURCE are defined, MINSIGSTKSZ and SIGSTKSZ are no longer
>    constant on Linux.  MINSIGSTKSZ is redefined to sysconf(_SC_MINSIGSTKSZ)
>    and SIGSTKSZ is redefined to sysconf (_SC_SIGSTKSZ).  This supports
>    dynamic sized register sets for modern architectural features like
>    Arm SVE.
> 
> Build error with the GNU C Library 2.34:
> DEBUG:	| sigreturn.c:150:13: error: variably modified 'altstack_data' at file scope
> | sigreturn.c:150:13: error: variably modified 'altstack_data' at file scope
> DEBUG:	|   150 | static char altstack_data[SIGSTKSZ];
> |   150 | static char altstack_data[SIGSTKSZ];
> DEBUG:	|       |             ^~~~~~~~~~~~~
> 

Please give more context on why this change is needed?

Doesn't look like you tried to compile this patch before
sending this to me.

> Signed-off-by: Jun Miao <jun.miao@windriver.com>


thanks,
-- Shuah

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [V2][PATCH] selftests/x86: Fix error: variably modified 'altstack_data' at file scope
  2021-08-23 13:56 [V2][PATCH] selftests/x86: Fix error: variably modified 'altstack_data' at file scope Jun Miao
  2021-08-23 20:29 ` Shuah Khan
@ 2021-08-23 22:48 ` kernel test robot
  1 sibling, 0 replies; 3+ messages in thread
From: kernel test robot @ 2021-08-23 22:48 UTC (permalink / raw)
  To: Jun Miao, shuah; +Cc: kbuild-all, linux-kselftest, linux-kernel, jun.miao

[-- Attachment #1: Type: text/plain, Size: 2187 bytes --]

Hi Jun,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kselftest/next]
[also build test ERROR on v5.14-rc7 next-20210823]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Jun-Miao/selftests-x86-Fix-error-variably-modified-altstack_data-at-file-scope/20210823-215819
base:   https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: x86_64-rhel-8.3-kselftests (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/3752736483bd2f09d350c5d3a42460d74ea9c53a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Jun-Miao/selftests-x86-Fix-error-variably-modified-altstack_data-at-file-scope/20210823-215819
        git checkout 3752736483bd2f09d350c5d3a42460d74ea9c53a
        # save the attached .config to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash -C tools/testing/selftests install

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   single_step_syscall.c: In function 'main':
>> single_step_syscall.c:230:7: error: 'stack' undeclared (first use in this function); did you mean 'stack_t'?
     230 |  free(stack.ss_sp);
         |       ^~~~~
         |       stack_t
   single_step_syscall.c:230:7: note: each undeclared identifier is reported only once for each function it appears in
--
   mov_ss_trap.c: In function 'main':
>> mov_ss_trap.c:284:7: error: 'stack' undeclared (first use in this function); did you mean 'obstack'?
     284 |  free(stack.ss_sp);
         |       ^~~~~
         |       obstack
   mov_ss_trap.c:284:7: note: each undeclared identifier is reported only once for each function it appears in

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 42150 bytes --]

^ permalink raw reply	[flat|nested] 3+ messages in thread

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2021-08-23 13:56 [V2][PATCH] selftests/x86: Fix error: variably modified 'altstack_data' at file scope Jun Miao
2021-08-23 20:29 ` Shuah Khan
2021-08-23 22:48 ` kernel test robot

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