diff options
| author | Andy Lutomirski <luto@kernel.org> | 2015-03-18 18:33:30 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-23 11:13:41 +0100 |
| commit | 383f3af3f88aadafe1fcf1948987ad538683fb8c (patch) | |
| tree | 026e66b686487ce83da463d2f2e6183e6ec20520 | |
| parent | a67e7277d01ccfd39b0db5a198c2643cc19dd79c (diff) | |
x86/asm/entry, perf: Explicitly optimize vm86 handling in code_segment_base()
There's no point in checking the VM bit on 64-bit, and, since
we're explicitly checking it, we can use user_mode_ignore_vm86()
after the check.
While we're at it, rearrange the #ifdef slightly to make the code
flow a bit clearer.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/dc1457a734feccd03a19bb3538a7648582f57cdd.1426728647.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 979963bb3977..56f7e60ad732 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -2147,18 +2147,19 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) static unsigned long code_segment_base(struct pt_regs *regs) { /* + * For IA32 we look at the GDT/LDT segment base to convert the + * effective IP to a linear address. + */ + +#ifdef CONFIG_X86_32 + /* * If we are in VM86 mode, add the segment offset to convert to a * linear address. */ if (regs->flags & X86_VM_MASK) return 0x10 * regs->cs; - /* - * For IA32 we look at the GDT/LDT segment base to convert the - * effective IP to a linear address. - */ -#ifdef CONFIG_X86_32 - if (user_mode(regs) && regs->cs != __USER_CS) + if (user_mode_ignore_vm86(regs) && regs->cs != __USER_CS) return get_segment_base(regs->cs); #else if (user_mode(regs) && !user_64bit_mode(regs) && |