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Commit 3aa4b37d authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
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x86: make traps on entry code be debuggable in user space, 64-bit 



Unify the x86-64 behavior for 32-bit processes that set
bogus %cs/%ss values (the only ones that can fault in iret)
match what the native i386 behavior is. (do not kill the task
via do_exit but generate a SIGSEGV signal)

[ tglx@linutronix.de: build fix ]

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 551e4fb2

arch/x86/kernel/entry_64.S

+15 −6
Original line number Diff line number Diff line
@@ -593,13 +593,22 @@ ENTRY(native_iret) 
	.quad native_iret, bad_iret

	.previous

	.section .fixup,"ax"

	/* force a signal here? this matches i386 behaviour */

	/* running with kernel gs */

bad_iret:

	movq $11,%rdi	/* SIGSEGV */

	TRACE_IRQS_ON

	ENABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI))

	jmp do_exit

	/*

	 * The iret traps when the %cs or %ss being restored is bogus.

	 * We've lost the original trap vector and error code.

	 * #GPF is the most likely one to get for an invalid selector.

	 * So pretend we completed the iret and took the #GPF in user mode.

	 *

	 * We are now running with the kernel GS after exception recovery.

	 * But error_entry expects us to have user GS to match the user %cs,

	 * so swap back.

	 */

	pushq $0



	SWAPGS

	jmp general_protection



	.previous



	/* edi: workmask, edx: work */