[PATCH] fix broken vm86 interrupt/signal handling

From: Aleksey Gorelov
Date: Fri May 19 2006 - 18:09:37 EST


This patch
=c3ff8ec31c1249d268cd11390649768a12bec1b9 has broken vm86
interrupt/signal handling in case when vm86 is called from kernel space.
In this scenario, if signal is pending because of vm86 interrupt,
do_notify_resume/do_signal exits immediately due to user_mode() check,
without processing any signals. Thus, resume_userspace handler is
spinning in a tight loop with signal pending and TIF_SIGPENDING is set.
Previously everything worked Ok.

The following patch fixes the issue

Signed-off-by: Aleksey Gorelov <aleksey_gorelov@xxxxxxxxxxx>

--- linux-2.6.16/arch/i386/kernel/entry.S-old 2006-05-19
14:31:41.000000000 -0700
+++ linux-2.6.16/arch/i386/kernel/entry.S 2006-05-19
14:33:31.000000000 -0700
@@ -82,6 +82,12 @@
#define resume_kernel restore_nocheck

+#ifdef CONFIG_VM86
+#define resume_userspace_sig check_userspace
+#define resume_userspace_sig resume_userspace
#define SAVE_ALL \
cld; \
pushl %es; \
@@ -143,6 +149,7 @@
movl EFLAGS(%esp), %eax # mix EFLAGS and CS
movb CS(%esp), %al
testl $(VM_MASK | 3), %eax
@@ -319,7 +326,7 @@
# vm86-space
xorl %edx, %edx
call do_notify_resume
- jmp resume_userspace
+ jmp resume_userspace_sig

@@ -330,7 +337,7 @@
movl %eax, %esp
xorl %edx, %edx
call do_notify_resume
- jmp resume_userspace
+ jmp resume_userspace_sig

# perform syscall exit tracing
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