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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: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Roland McGrath 2008-02-06 22:39:43 +01:00 committed by Ingo Molnar
parent 551e4fb246
commit 3aa4b37d3e
1 changed files with 15 additions and 6 deletions
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21
arch/x86/kernel/entry_64.S
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@ -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 */