Commit-ID: 383f3af3f88aadafe1fcf1948987ad538683fb8c Gitweb: http://git.kernel.org/tip/383f3af3f88aadafe1fcf1948987ad538683fb8c Author: Andy Lutomirski <[email protected]> AuthorDate: Wed, 18 Mar 2015 18:33:30 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 23 Mar 2015 11:13:41 +0100
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 <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brad Spengler <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/dc1457a734feccd03a19bb3538a7648582f57cdd.1426728647.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/cpu/perf_event.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 979963b..56f7e60 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) && -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
