There are a few places in libgcc assembly where we don't emit call
frame information for functions, potentially breaking unwinding from
asynchronous signal handlers. This patch fixes most. Although I
patch tramp.S there is no attempt made to provide CFI for the actual
trampoline on the stack. Doing that would require generating CFI at
run time and both registering and deregistering it, which is probably
not worth doing since it would significantly slow down the call.
Note that the out-of-line register save/restore functions do not
need CFI in the assembly. CFI is added for them by the rs6000.c
prologue and epilogue code.
Bootstrapped etc. powerpc64le-linux.
* config/rs6000/morestack.S (__stack_split_initialize),
(__morestack_get_guard, __morestack_set_guard),
(__morestack_make_guard): Provide CFI covering these functions.
* config/rs6000/tramp.S (__trampoline_setup): Likewise.
diff --git a/libgcc/config/rs6000/morestack.S b/libgcc/config/rs6000/morestack.S
index a0fee4037e4..936051eab33 100644
--- a/libgcc/config/rs6000/morestack.S
+++ b/libgcc/config/rs6000/morestack.S
@@ -304,12 +304,15 @@ DW.ref.__gcc_personality_v0:
# new thread starts. This is called from a constructor.
# void __stack_split_initialize (void)
ENTRY(__stack_split_initialize)
+ .cfi_startproc
addi %r3,%r1,-0x4000 # We should have at least 16K.
std %r3,-0x7000-64(%r13) # tcbhead_t.__private_ss
# void __generic_morestack_set_initial_sp (void *sp, size_t len)
mr %r3,%r1
li %r4, 0x4000
b __generic_morestack_set_initial_sp
+# The lack of .cfi_endproc here is deliberate. This function and the
+# following ones can all use the default FDE.
SIZE (__stack_split_initialize)
@@ -335,6 +338,7 @@ ENTRY0(__morestack_make_guard)
sub %r3,%r3,%r4
addi %r3,%r3,BACKOFF
blr
+ .cfi_endproc
SIZE (__morestack_make_guard)
diff --git a/libgcc/config/rs6000/tramp.S b/libgcc/config/rs6000/tramp.S
index 19ea57838fc..637f4510146 100644
--- a/libgcc/config/rs6000/tramp.S
+++ b/libgcc/config/rs6000/tramp.S
@@ -56,8 +56,10 @@ trampoline_size = .-trampoline_initial
/* R6 = static chain */
FUNC_START(__trampoline_setup)
+ .cfi_startproc
mflr r0 /* save return address */
bcl 20,31,.LCF0 /* load up __trampoline_initial into r7 */
+ .cfi_register lr,r0
.LCF0:
mflr r11
addi r7,r11,trampoline_initial-4-.LCF0 /* trampoline address -4 */
@@ -112,6 +114,7 @@ FUNC_START(__trampoline_setup)
addi r30,r30,_GLOBAL_OFFSET_TABLE_-1b@l
#endif
bl JUMP_TARGET(abort)
+ .cfi_endproc
FUNC_END(__trampoline_setup)
#endif
@@ -144,6 +147,7 @@ trampoline_size = .-trampoline_initial
.popsection
FUNC_START(__trampoline_setup)
+ .cfi_startproc
addis 7,2,.LC0@toc@ha
ld 7,.LC0@toc@l(7) /* trampoline address -8 */
@@ -180,6 +184,7 @@ FUNC_START(__trampoline_setup)
.Labort:
bl JUMP_TARGET(abort)
nop
+ .cfi_endproc
FUNC_END(__trampoline_setup)
#endif
--
Alan Modra
Australia Development Lab, IBM
