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Commit c7498081 authored by David S. Miller's avatar David S. Miller
Browse files

sparc64: Fix recursion in stack overflow detection handling. 



The calls down into prom_printf() when we detect an overflowed stack
can recurse again since the overflow stack will be "below" the current
kernel stack limit.

Prevent this by just returning straight if we are on the stack
overflow safe stack already.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c6ed413d

arch/sparc64/lib/mcount.S

+14 −3
Original line number Diff line number Diff line
@@ -48,12 +48,23 @@ mcount: 
	sub		%g3, STACK_BIAS, %g3

	cmp		%sp, %g3

	bg,pt		%xcc, 1f

	 sethi		%hi(panicstring), %g3

	 nop

	/* If we are already on ovstack, don't hop onto it

	 * again, we are already trying to output the stack overflow

	 * message.

	 */

	sethi		%hi(ovstack), %g7		! cant move to panic stack fast enough

	 or		%g7, %lo(ovstack), %g7

	add		%g7, OVSTACKSIZE, %g7

	add		%g7, OVSTACKSIZE, %g3

	sub		%g3, STACK_BIAS + 192, %g3

	sub		%g7, STACK_BIAS, %g7

	mov		%g7, %sp

	cmp		%sp, %g7

	blu,pn		%xcc, 2f

	 cmp		%sp, %g3

	bleu,pn		%xcc, 1f

	 nop

2:	mov		%g3, %sp

	sethi		%hi(panicstring), %g3

	call		prom_printf

	 or		%g3, %lo(panicstring), %o0

	call		prom_halt