LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Borislav Petkov <bp@alien8.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
linux-tip-commits@vger.kernel.org, linux-kernel@vger.kernel.org,
keescook@chromium.org, ast@plumgrid.com, fweisbec@gmail.com,
oleg@redhat.com, tglx@linutronix.de,
torvalds@linux-foundation.org, hpa@zytor.com, wad@chromium.org,
rostedt@goodmis.org
Subject: Re: [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct::usersp
Date: Tue, 17 Mar 2015 08:39:01 +0100 [thread overview]
Message-ID: <20150317073901.GC19645@pd.tnic> (raw)
In-Reply-To: <20150317072118.GA26864@gmail.com>
On Tue, Mar 17, 2015 at 08:21:18AM +0100, Ingo Molnar wrote:
> Assuming this does not fix the regression, could you apply the minimal
> patch below - which reverts the old_rsp handling change.
>
> (The rest of the commit are in a third patch, but those are only
> comment changes.)
>
> So my theory is that this change is what will revert the regression.
Yep, it does. Below is the diff that works (it is the rough revert
without the comments :-)):
---
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 66a1954439ea..e39bf83cb55b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -496,6 +496,7 @@ struct thread_struct {
#ifdef CONFIG_X86_32
unsigned long sysenter_cs;
#else
+ unsigned long usersp; /* Copy from PDA */
unsigned short es;
unsigned short ds;
unsigned short fsindex;
@@ -907,6 +908,11 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk);
#define task_pt_regs(tsk) ((struct pt_regs *)(tsk)->thread.sp0 - 1)
extern unsigned long KSTK_ESP(struct task_struct *task);
+/*
+ * User space RSP while inside the SYSCALL fast path
+ */
+DECLARE_PER_CPU(unsigned long, old_rsp);
+
#endif /* CONFIG_X86_64 */
extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 14df2be4711f..e8c124a1f885 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -161,6 +161,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.sp0 = (unsigned long)task_stack_page(p) + THREAD_SIZE;
childregs = task_pt_regs(p);
p->thread.sp = (unsigned long) childregs;
+ p->thread.usersp = me->thread.usersp;
set_tsk_thread_flag(p, TIF_FORK);
p->thread.io_bitmap_ptr = NULL;
@@ -234,8 +235,10 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip,
loadsegment(es, _ds);
loadsegment(ds, _ds);
load_gs_index(0);
+ current->thread.usersp = new_sp;
regs->ip = new_ip;
regs->sp = new_sp;
+ this_cpu_write(old_rsp, new_sp);
regs->cs = _cs;
regs->ss = _ss;
regs->flags = X86_EFLAGS_IF;
@@ -395,6 +398,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
/*
* Switch the PDA and FPU contexts.
*/
+ prev->usersp = this_cpu_read(old_rsp);
+ this_cpu_write(old_rsp, next->usersp);
this_cpu_write(current_task, next_p);
/*
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-03-17 7:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-10 10:45 [PATCH 2/4] x86: entry_64.S: remove stub_iopl Denys Vlasenko
2015-03-10 10:45 ` [PATCH 4/4] x86: entry_64.S: remove unused thread_struct::usersp Denys Vlasenko
2015-03-11 12:55 ` Borislav Petkov
2015-03-11 15:19 ` Denys Vlasenko
2015-03-16 12:05 ` [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct:: usersp tip-bot for Denys Vlasenko
2015-03-16 16:47 ` Borislav Petkov
2015-03-16 22:20 ` [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct::usersp Denys Vlasenko
2015-03-17 7:08 ` Borislav Petkov
2015-03-17 7:13 ` Ingo Molnar
2015-03-17 7:21 ` Ingo Molnar
2015-03-17 7:39 ` Borislav Petkov [this message]
2015-03-17 12:22 ` Denys Vlasenko
2015-03-17 12:51 ` Denys Vlasenko
2015-03-17 7:51 ` Ingo Molnar
2015-03-17 8:06 ` Borislav Petkov
2015-03-17 8:27 ` Ingo Molnar
2015-03-17 9:01 ` Borislav Petkov
2015-03-11 12:08 ` [PATCH 2/4] x86: entry_64.S: remove stub_iopl Borislav Petkov
2015-03-16 12:05 ` [tip:x86/asm] x86/asm/entry/64: Remove stub_iopl tip-bot for Denys Vlasenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150317073901.GC19645@pd.tnic \
--to=bp@alien8.de \
--cc=ast@plumgrid.com \
--cc=dvlasenk@redhat.com \
--cc=fweisbec@gmail.com \
--cc=hpa@zytor.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=wad@chromium.org \
--subject='Re: [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct::usersp' \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).