From 9565a349f217fb6f532fac06b7ef458a32c2ad2e Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sun, 18 Nov 2012 22:57:32 -0500 Subject: fix powerpc asm not to store data in volatile space below stack pointer it's essential to decrement the stack pointer before writing to new stack space, rather than afterwards. otherwise there is a race condition during which asynchronous code (signals) could clobber the data being stored. it may be possible to optimize the code further using stwu, but I wanted to avoid making any changes to the actual stack layout in this commit. further improvements can be made separately if desired. --- src/signal/powerpc/sigsetjmp.s | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'src/signal') diff --git a/src/signal/powerpc/sigsetjmp.s b/src/signal/powerpc/sigsetjmp.s index 81f5a40e..deed732f 100644 --- a/src/signal/powerpc/sigsetjmp.s +++ b/src/signal/powerpc/sigsetjmp.s @@ -10,25 +10,25 @@ sigsetjmp: #2) if its 0, goto setjmp code beq- cr7, 1f #3) else: we must call pthread_sigmask(SIG_SETMASK, 0, (sigset_t *)buf->__ss); + # increase stack frame by 16 + subi 1, 1, 16 # thus store r3 on the stack, to restore it later - stw 3, -4(1) + stw 3, 12(1) # store old link reg mflr 0 - stw 0, -8(1) - # increase stack frame by 16 - subi 1, 1, 16 + stw 0, 8(1) # put pointer to ss buf into r5 (3rd arg) addi 5, 3, 260 # put "2" i.e. SIG_SETMASK in r3 li 3, 2 li 4, 0 bl pthread_sigmask - #restore sp - addi 1, 1, 16 #restore r3 - lwz 3, -4(1) + lwz 3, 12(1) #restore link reg - lwz 0, -8(1) + lwz 0, 8(1) mtlr 0 + #restore sp + addi 1, 1, 16 1: b setjmp -- cgit v1.2.1