Commit-ID: 36acef2510853e2831047ca9e22d333ba7a1047b Gitweb: http://git.kernel.org/tip/36acef2510853e2831047ca9e22d333ba7a1047b Author: Denys Vlasenko <dvlasenk@xxxxxxxxxx> AuthorDate: Tue, 31 Mar 2015 19:00:07 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Wed, 1 Apr 2015 13:17:39 +0200 x86/asm/entry/64: Simplify looping around preempt_schedule_irq() At the 'exit_intr' label we test whether interrupt/exception was in kernel. If it did, we jump to the preemption check. If preemption does happen (IOW if we call preempt_schedule_irq()), we go back to 'exit_intr'. But it's pointless, we already know that the test succeeded last time, preemption doesn't change the fact that interrupt/exception was in the kernel. We can go back directly to checking PER_CPU_VAR(__preempt_count) instead. This makes the 'exit_intr' label unused, drop it. Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Will Drewry <wad@xxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1427821211-25099-5-git-send-email-dvlasenk@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/kernel/entry_64.S | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 9f8d01f..bad285d 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -654,7 +654,6 @@ ret_from_intr: CFI_DEF_CFA_REGISTER rsp CFI_ADJUST_CFA_OFFSET RBP -exit_intr: testl $3,CS(%rsp) je retint_kernel /* Interrupt came from user space */ @@ -741,12 +740,12 @@ retint_kernel: #ifdef CONFIG_PREEMPT /* Interrupts are off */ /* Check if we need preemption */ - cmpl $0,PER_CPU_VAR(__preempt_count) - jnz 1f bt $9,EFLAGS(%rsp) /* interrupts were off? */ jnc 1f +0: cmpl $0,PER_CPU_VAR(__preempt_count) + jnz 1f call preempt_schedule_irq - jmp exit_intr + jmp 0b 1: #endif /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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