|
 |
5de29b |
# commit 5162e7dd96efcd9b45c1dc1471a964d45278b1e1
|
|
|
5de29b |
# Author: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
|
|
|
5de29b |
# Date: Wed Dec 4 06:41:52 2013 -0600
|
|
|
5de29b |
#
|
|
|
5de29b |
# PowerPC64: Fix incorrect CFI in *context routines
|
|
|
5de29b |
#
|
|
|
5de29b |
# The context established by "makecontext" has a link register pointing
|
|
|
5de29b |
# back to an error path within the makecontext routine. This is currently
|
|
|
5de29b |
# covered by the CFI FDE for makecontext itself, which is simply wrong
|
|
|
5de29b |
# for the stack frame *inside* the context. When trying to unwind (e.g.
|
|
|
5de29b |
# doing a backtrace) in a routine inside a context created by makecontext,
|
|
|
5de29b |
# this can lead to uninitialized stack slots being accessed, causing the
|
|
|
5de29b |
# unwinder to crash in the worst case.
|
|
|
5de29b |
#
|
|
|
5de29b |
# Similarly, during parts of the "setcontext" routine, when the stack
|
|
|
5de29b |
# pointer has already been switched to point to the new context, the
|
|
|
5de29b |
# address range is still covered by the CFI FDE for setcontext. When
|
|
|
5de29b |
# trying to unwind in that situation (e.g. backtrace from an async
|
|
|
5de29b |
# signal handler for profiling), it is again possible that the unwinder
|
|
|
5de29b |
# crashes.
|
|
|
5de29b |
#
|
|
|
5de29b |
# Theses are all problems in existing code, but the changes in stack
|
|
|
5de29b |
# frame layout appear to make the "worst case" much more likely in
|
|
|
5de29b |
# the ELFv2 ABI context. This causes regressions e.g. in the libgo
|
|
|
5de29b |
# testsuite on ELFv2.
|
|
|
5de29b |
#
|
|
|
5de29b |
# This patch fixes this by ending the makecontext/setcontext FDEs
|
|
|
5de29b |
# before those problematic parts of the assembler, similar to what
|
|
|
5de29b |
# is already done on other platforms. This fixes the libgo
|
|
|
5de29b |
# regression on ELFv2.
|
|
|
5de29b |
#
|
|
|
12745e |
diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S
|
|
|
12745e |
--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S 2014-05-29 13:16:16.000000000 -0500
|
|
|
12745e |
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S 2014-05-29 13:16:17.000000000 -0500
|
|
|
5de29b |
@@ -129,6 +129,10 @@
|
|
|
5de29b |
the cpu link stack used to predict blr return addresses. */
|
|
|
5de29b |
bcl 20,31,L(gotexitcodeaddr);
|
|
|
5de29b |
|
|
|
5de29b |
+ /* End FDE now, because while executing on the context's stack
|
|
|
5de29b |
+ the unwind info would be wrong otherwise. */
|
|
|
5de29b |
+ cfi_endproc
|
|
|
5de29b |
+
|
|
|
5de29b |
/* This is the helper code which gets called if a function which
|
|
|
5de29b |
is registered with 'makecontext' returns. In this case we
|
|
|
5de29b |
have to install the context listed in the uc_link element of
|
|
|
5de29b |
@@ -157,6 +161,11 @@
|
|
|
5de29b |
#endif
|
|
|
5de29b |
b L(do_exit)
|
|
|
5de29b |
|
|
|
5de29b |
+ /* Re-establish FDE for the rest of the actual makecontext routine. */
|
|
|
5de29b |
+ cfi_startproc
|
|
|
5de29b |
+ cfi_offset (lr, FRAME_LR_SAVE)
|
|
|
5de29b |
+ cfi_adjust_cfa_offset (128)
|
|
|
5de29b |
+
|
|
|
5de29b |
/* The address of the exit code is in the link register. Store the lr
|
|
|
5de29b |
in the ucontext as LNK so the target function will return to our
|
|
|
5de29b |
exit code. */
|
|
|
12745e |
diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S
|
|
|
12745e |
--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S 2014-05-29 13:16:16.000000000 -0500
|
|
|
12745e |
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/setcontext.S 2014-05-29 13:16:17.000000000 -0500
|
|
|
5de29b |
@@ -129,6 +129,10 @@
|
|
|
5de29b |
lfd fp1,(SIGCONTEXT_FP_REGS+(PT_R1*8))(r31)
|
|
|
5de29b |
lfd fp0,(SIGCONTEXT_FP_REGS+(PT_R0*8))(r31)
|
|
|
5de29b |
|
|
|
5de29b |
+ /* End FDE now, because the unwind info would be wrong while
|
|
|
5de29b |
+ we're reloading registers to switch to the new context. */
|
|
|
5de29b |
+ cfi_endproc
|
|
|
5de29b |
+
|
|
|
5de29b |
ld r0,(SIGCONTEXT_GP_REGS+(PT_LNK*8))(r31)
|
|
|
5de29b |
ld r1,(SIGCONTEXT_GP_REGS+(PT_R1*8))(r31)
|
|
|
5de29b |
mtlr r0
|
|
|
5de29b |
@@ -177,6 +181,11 @@
|
|
|
5de29b |
ld r31,(SIGCONTEXT_GP_REGS+(PT_R31*8))(r31)
|
|
|
5de29b |
bctr
|
|
|
5de29b |
|
|
|
5de29b |
+ /* Re-establish FDE for the rest of the actual setcontext routine. */
|
|
|
5de29b |
+ cfi_startproc
|
|
|
5de29b |
+ cfi_offset (lr, FRAME_LR_SAVE)
|
|
|
5de29b |
+ cfi_adjust_cfa_offset (128)
|
|
|
5de29b |
+
|
|
|
5de29b |
L(nv_error_exit):
|
|
|
5de29b |
ld r0,128+FRAME_LR_SAVE(r1)
|
|
|
5de29b |
addi r1,r1,128
|
|
|
5de29b |
@@ -403,6 +412,10 @@
|
|
|
5de29b |
lfd fp1,(SIGCONTEXT_FP_REGS+(PT_R1*8))(r31)
|
|
|
5de29b |
lfd fp0,(SIGCONTEXT_FP_REGS+(PT_R0*8))(r31)
|
|
|
5de29b |
|
|
|
5de29b |
+ /* End FDE now, because the unwind info would be wrong while
|
|
|
5de29b |
+ we're reloading registers to switch to the new context. */
|
|
|
5de29b |
+ cfi_endproc
|
|
|
5de29b |
+
|
|
|
5de29b |
ld r0,(SIGCONTEXT_GP_REGS+(PT_LNK*8))(r31)
|
|
|
5de29b |
ld r1,(SIGCONTEXT_GP_REGS+(PT_R1*8))(r31)
|
|
|
5de29b |
mtlr r0
|
|
|
5de29b |
@@ -451,6 +464,11 @@
|
|
|
5de29b |
ld r31,(SIGCONTEXT_GP_REGS+(PT_R31*8))(r31)
|
|
|
5de29b |
bctr
|
|
|
5de29b |
|
|
|
5de29b |
+ /* Re-establish FDE for the rest of the actual setcontext routine. */
|
|
|
5de29b |
+ cfi_startproc
|
|
|
5de29b |
+ cfi_offset (lr, FRAME_LR_SAVE)
|
|
|
5de29b |
+ cfi_adjust_cfa_offset (128)
|
|
|
5de29b |
+
|
|
|
5de29b |
L(error_exit):
|
|
|
5de29b |
ld r0,128+FRAME_LR_SAVE(r1)
|
|
|
5de29b |
addi r1,r1,128
|