On systems that support fast syscalls, we only really care about the
performance of the fast syscall path. Forcibly inline it and add
a likely annotation.
This saves 4-6 cycles.
Signed-off-by: Andy Lutomirski <l...@kernel.org>
---
arch/x86/entry/common.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 0fa55f0736f6..a3c4e7aa573b 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -324,9 +324,11 @@ __visible void syscall_return_slowpath(struct pt_regs
*regs)
#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
/*
* Does a 32-bit syscall. Called with IRQs on and does all entry and
- * exit work and returns with IRQs off.
+ * exit work and returns with IRQs off. This function is extremely hot
+ * in workloads that use it, and it's usually called from
+ * do_fast_syscall_32, so forcibly inline it to improve performance.
*/
-static void do_syscall_32_irqs_on(struct pt_regs *regs)
+static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
{
struct thread_info *ti = pt_regs_to_thread_info(regs);
unsigned int nr = (unsigned int)regs->orig_ax;
@@ -345,7 +347,7 @@ static void do_syscall_32_irqs_on(struct pt_regs *regs)
nr = syscall_trace_enter(regs);
}
- if (nr < IA32_NR_syscalls) {
+ if (likely(nr < IA32_NR_syscalls)) {
/*
* It's possible that a 32-bit syscall implementation
* takes a 64-bit parameter but nonetheless assumes that
--
2.4.3
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