lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon,  5 Oct 2015 17:48:19 -0700
From:	Andy Lutomirski <>
Cc:	Brian Gerst <>,
	Denys Vlasenko <>,
	Linus Torvalds <>,
	Borislav Petkov <>,
	Andy Lutomirski <>
Subject: [PATCH v2 31/36] x86/entry: Force inlining of 32-bit syscall code

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 <>
 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 1d95f8835322..6e1ea6a401f2 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

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists