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| author | Ingo Molnar <mingo@kernel.org> | 2015-03-17 13:42:59 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-17 15:01:41 (GMT) |
| commit | 9854dd74c3f6af8d9d527de86c6074b7ed0495f1 (patch) | |
| tree | 9e37ff521247975e3e37359ff54c050811ed98a4 /arch/x86/kernel/process_64.c | |
| parent | 33db1fd48ac3d90385b412b41a8a6525096ac6d5 (diff) | |
| download | linux-9854dd74c3f6af8d9d527de86c6074b7ed0495f1.tar.xz | |
x86/asm/entry/64: Simplify 'old_rsp' usage
Remove all manipulations of PER_CPU(old_rsp) in C code:
- it is not used on SYSRET return anymore, and system entries
are atomic, so updating it from the fork and context switch
paths is pointless.
- Tweak a few related comments as well: we no longer have a
"partial stack frame" on entry, ever.
Based on (split out of) patch from Denys Vlasenko.
Originally-from: Denys Vlasenko <dvlasenk@redhat.com>
Tested-by: Borislav Petkov <bp@alien8.de>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1426599779-8010-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index e8c124a..59696d7 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -238,7 +238,6 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip, 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; @@ -399,7 +398,6 @@ __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); /* |