When I rewrote entry_INT80_32, I thought that int80 was an interrupt
gate. It's a trap gate. *facepalm*
Thanks to Brian Gerst for pointing out that it's better to change
the entry code than to change the gate type.
Suggested-by: Brian Gerst <brge...@gmail.com>
Reported-by: Borislav Petkov <b...@suse.de>
Fixes: 150ac78d63af ("x86/entry/32: Switch INT80 to the new C syscall path")
Signed-off-by: Andy Lutomirski <l...@kernel.org>
---
I can reproduce Borislav's warning with an appropriate .config, and this
patch fixes it. I removed the Tested-by, because it's not the same fix
that Borislav tested.
arch/x86/entry/common.c | 9 +--------
arch/x86/entry/entry_32.S | 8 ++++----
2 files changed, 5 insertions(+), 12 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index b53e04d301a3..b0293e0a60df 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -351,7 +351,7 @@ __visible inline void syscall_return_slowpath(struct
pt_regs *regs)
* in workloads that use it, and it's usually called from
* do_fast_syscall_32, so forcibly inline it to improve performance.
*/
-static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
+__visible __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;
@@ -386,13 +386,6 @@ static __always_inline void do_syscall_32_irqs_on(struct
pt_regs *regs)
syscall_return_slowpath(regs);
}
-/* Handles int $0x80 */
-__visible void do_int80_syscall_32(struct pt_regs *regs)
-{
- local_irq_enable();
- do_syscall_32_irqs_on(regs);
-}
-
/* Returns 0 to return using IRET or 1 to return using SYSEXIT/SYSRETL. */
__visible long do_fast_syscall_32(struct pt_regs *regs)
{
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 07a041b91af1..ba0dad937be9 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -346,13 +346,13 @@ ENTRY(entry_INT80_32)
SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */
/*
- * User mode is traced as though IRQs are on, and the interrupt gate
- * turned them off.
+ * 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).
*/
- TRACE_IRQS_OFF
movl %esp, %eax
- call do_int80_syscall_32
+ call do_syscall_32_irqs_on
.Lsyscall_32_done:
restore_all:
--
2.4.3
--
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