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Message-Id: <4ADD7E6C020000780001AD73@vpn.id2.novell.com> Date: Tue, 20 Oct 2009 08:10:04 +0100 From: "Jan Beulich" <JBeulich@...ell.com> To: <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com> Cc: <linux-kernel@...r.kernel.org> Subject: [PATCH] x86-64: adjust ia32entry branches for better static prediction Swap branch pairs so that the static branch prediction logic would consider the syscall-number-in-range case the taken path. Signed-off-by: Jan Beulich <jbeulich@...ell.com> --- arch/x86/ia32/ia32entry.S | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- linux-2.6.32-rc5/arch/x86/ia32/ia32entry.S 2009-10-19 13:12:43.000000000 +0200 +++ 2.6.32-rc5-x86_64-ia32-syscall-trace-branch-dir/arch/x86/ia32/ia32entry.S 2009-10-19 09:36:39.000000000 +0200 @@ -249,9 +249,9 @@ sysenter_tracesys: call syscall_trace_enter LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */ RESTORE_REST - cmpl $(IA32_NR_syscalls-1),%eax - ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */ - jmp sysenter_do_call + cmpl $IA32_NR_syscalls,%eax + jb sysenter_do_call + jmp int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */ CFI_ENDPROC ENDPROC(ia32_sysenter_target) @@ -368,9 +368,9 @@ cstar_tracesys: LOAD_ARGS32 ARGOFFSET, 1 /* reload args from stack in case ptrace changed it */ RESTORE_REST xchgl %ebp,%r9d - cmpl $(IA32_NR_syscalls-1),%eax - ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */ - jmp cstar_do_call + cmpl $IA32_NR_syscalls,%eax + jb cstar_do_call + jmp int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */ END(ia32_cstar_target) ia32_badarg: @@ -445,9 +445,9 @@ ia32_tracesys: call syscall_trace_enter LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */ RESTORE_REST - cmpl $(IA32_NR_syscalls-1),%eax - ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */ - jmp ia32_do_call + cmpl $IA32_NR_syscalls,%eax + jb ia32_do_call + jmp int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */ END(ia32_syscall) ia32_badsys: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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