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Commit a879cbbb authored by Linus Torvalds's avatar Linus Torvalds
Browse files

x86: make traps on 'iret' be debuggable in user space 

This makes a trap on the 'iret' that returns us to user space
cause a nice clean SIGSEGV, instead of just a hard (and silent)
exit.

That way a debugger can actually try to see what happened, and
we also properly notify everybody who might be interested about
us being gone.

This loses the error code, but tells the debugger what happened
with ILL_BADSTK in the siginfo.
parent c06fec50

arch/i386/kernel/entry.S

+3 −5
Original line number Diff line number Diff line
@@ -260,11 +260,9 @@ restore_nocheck: 
.section .fixup,"ax"

iret_exc:

	sti

	movl $__USER_DS, %edx

	movl %edx, %ds

	movl %edx, %es

	movl $11,%eax

	call do_exit

	pushl $0			# no error code

	pushl $do_iret_error

	jmp error_code

.previous

.section __ex_table,"a"

	.align 4

arch/i386/kernel/traps.c

+1 −0
Original line number Diff line number Diff line
@@ -451,6 +451,7 @@ DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS) 
DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present)

DO_ERROR(12, SIGBUS,  "stack segment", stack_segment)

DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)

DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0)



fastcall void do_general_protection(struct pt_regs * regs, long error_code)

{