From: Aleksey Gorelov Date: Tue, 27 Jun 2006 09:53:48 +0000 (-0700) Subject: [PATCH] fix broken vm86 interrupt/signal handling X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4031ff388138b58e5cd472dccce38828bcb8c706;p=linux-beck.git [PATCH] fix broken vm86 interrupt/signal handling Commit c3ff8ec31c1249d268cd11390649768a12bec1b9 ("[PATCH] i386: Don't miss pending signals returning to user mode after signal processing") meant that vm86 interrupt/signal handling got broken for the 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. No in-tree usage of vm86() from kernel space exists, but I've heard about a number of projects out there which use vm86 calls from kernel, one of them being this, for instance: http://dev.gentoo.org/~spock/projects/vesafb-tng/ The following patch fixes the issue. Signed-off-by: Aleksey Gorelov Cc: Atsushi Nemoto Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 8713e0248a0b..e8d2630fd19a 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -83,6 +83,12 @@ VM_MASK = 0x00020000 #define resume_kernel restore_nocheck #endif +#ifdef CONFIG_VM86 +#define resume_userspace_sig check_userspace +#else +#define resume_userspace_sig resume_userspace +#endif + #define SAVE_ALL \ cld; \ pushl %es; \ @@ -211,6 +217,7 @@ ret_from_exception: preempt_stop ret_from_intr: GET_THREAD_INFO(%ebp) +check_userspace: movl EFLAGS(%esp), %eax # mix EFLAGS and CS movb CS(%esp), %al testl $(VM_MASK | 3), %eax @@ -415,7 +422,7 @@ work_notifysig: # deal with pending signals and # vm86-space xorl %edx, %edx call do_notify_resume - jmp resume_userspace + jmp resume_userspace_sig ALIGN work_notifysig_v86: @@ -428,7 +435,7 @@ work_notifysig_v86: movl %eax, %esp xorl %edx, %edx call do_notify_resume - jmp resume_userspace + jmp resume_userspace_sig #endif # perform syscall exit tracing