Commit-ID: 9854dd74c3f6af8d9d527de86c6074b7ed0495f1 Gitweb: http://git.kernel.org/tip/9854dd74c3f6af8d9d527de86c6074b7ed0495f1 Author: Ingo Molnar <mi...@kernel.org> AuthorDate: Tue, 17 Mar 2015 14:42:59 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 17 Mar 2015 16:01:41 +0100
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 <dvlas...@redhat.com> Tested-by: Borislav Petkov <b...@alien8.de> Acked-by: Borislav Petkov <b...@alien8.de> Cc: Alexei Starovoitov <a...@plumgrid.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Oleg Nesterov <o...@redhat.com> Cc: Steven Rostedt <rost...@goodmis.org> Cc: Will Drewry <w...@chromium.org> Link: http://lkml.kernel.org/r/1426599779-8010-2-git-send-email-dvlas...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/include/asm/processor.h | 5 ----- arch/x86/kernel/process_64.c | 2 -- 2 files changed, 7 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 5abd9a5..3ac5092 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -905,11 +905,6 @@ 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 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); /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
