Commit-ID: 8b13c2552ffc8e54e57598df36707183933e8e8c
Gitweb: http://git.kernel.org/tip/8b13c2552ffc8e54e57598df36707183933e8e8c
Author: Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Mon, 5 Oct 2015 17:48:17 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 9 Oct 2015 09:41:11 +0200
x86/entry: Remove unnecessary IRQ twiddling in fast 32-bit syscalls
This is slightly messy, but it eliminates an unnecessary cli;sti
pair.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/22f34b1096694a37326f36c53407b8dd90f37948.1444091585.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/entry/common.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 0ed023d..0d1c842 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -323,10 +323,10 @@ __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 off and does all entry and
- * exit work.
+ * Does a 32-bit syscall. Called with IRQs on and does all entry and
+ * exit work and returns with IRQs off.
*/
-__visible void do_int80_syscall_32(struct pt_regs *regs)
+static 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;
@@ -335,8 +335,6 @@ __visible void do_int80_syscall_32(struct pt_regs *regs)
ti->status |= TS_COMPAT;
#endif
- local_irq_enable();
-
if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) {
/*
* Subtlety here: if ptrace pokes something larger than
@@ -363,6 +361,13 @@ __visible void do_int80_syscall_32(struct pt_regs *regs)
syscall_return_slowpath(regs);
}
+/* Handles int $0x80 */
+__visible void do_int80_syscall_32(struct pt_regs *regs)
+{
+ local_irq_enable();
+ do_syscall_32_irqs_on(regs);
+}
+
/* Returns 0 to return using IRET or 1 to return using SYSEXIT/SYSRETL. */
__visible long do_fast_syscall_32(struct pt_regs *regs)
{
@@ -398,10 +403,9 @@ __visible long do_fast_syscall_32(struct pt_regs *regs)
prepare_exit_to_usermode(regs);
return 0; /* Keep it simple: use IRET. */
}
- local_irq_disable();
/* Now this is just like a normal syscall. */
- do_int80_syscall_32(regs);
+ do_syscall_32_irqs_on(regs);
#ifdef CONFIG_X86_64
/*
--
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