From a798f091113ef4999277dbe0483d37d04fa35b2e Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 9 Mar 2016 13:24:32 -0800 Subject: x86/entry/32: Change INT80 to be an interrupt gate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We want all of the syscall entries to run with interrupts off so that we can efficiently run context tracking before enabling interrupts. This will regress int $0x80 performance on 32-bit kernels by a couple of cycles. This shouldn't matter much -- int $0x80 is not a fast path. This effectively reverts: 657c1eea0019 ("x86/entry/32: Fix entry_INT80_32() to expect interrupts to be on") ... and fixes the same issue differently. Signed-off-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Frédéric Weisbecker Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/59b4f90c9ebfccd8c937305dbbbca680bc74b905.1457558566.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/entry_32.S | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/x86/entry/entry_32.S') diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 286efa342091..10868aa734dc 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -463,13 +463,13 @@ ENTRY(entry_INT80_32) SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ /* - * User mode is traced as though IRQs are on. Unlike the 64-bit - * case, INT80 is a trap gate on 32-bit kernels, so interrupts - * are already on (unless user code is messing around with iopl). + * User mode is traced as though IRQs are on, and the interrupt gate + * turned them off. */ + TRACE_IRQS_OFF movl %esp, %eax - call do_syscall_32_irqs_on + call do_int80_syscall_32 .Lsyscall_32_done: restore_all: -- cgit v1.2.3