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Clear link register in __bionic_clone.

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Since __bionic_clone uses tail-call to invoke __bionic_clone_entry,
at runtime the unwinder will reach the stack of the clone() function,
which belongs to the parent thread, if the link register is not cleared.

BUG: 14270816
Change-Id: Ia3711c87f8b619debe73748c28b9fb8691ea698e
This commit is contained in:
Ben Cheng 2014-05-23 16:35:21 -07:00
parent a486632e78
commit 8df0fe0c74
2 changed files with 4 additions and 9 deletions
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9
libc/arch-arm/bionic/__bionic_clone.S
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@ -54,19 +54,14 @@ ENTRY(__bionic_clone)
# In the parent, reload saved registers then either return or set errno.
ldmfd sp!, {r4, r5, r6, r7}
.cfi_def_cfa_offset 0
cmn r0, #(MAX_ERRNO + 1)
bxls lr
neg r0, r0
b __set_errno
1: # The child.
# Re-add the unwind directives that were reset from above.
.cfi_def_cfa_offset 16
.cfi_rel_offset r4, 0
.cfi_rel_offset r5, 4
.cfi_rel_offset r6, 8
.cfi_rel_offset r7, 12
# Setting lr to 0 will make the unwinder stop at __bionic_clone_entry
mov lr, #0
ldr r0, [sp, #-4]
ldr r1, [sp, #-8]
b __bionic_clone_entry

4
libc/arch-arm64/bionic/__bionic_clone.S
View File

@ -61,9 +61,9 @@ ENTRY(__bionic_clone)
.L_bc_child:
# We're in the child now. Set the end of the frame record chain...
.cfi_undefined x29
.cfi_undefined x30
mov x29, xzr
# Setting x30 to 0 will make the unwinder stop at __bionic_clone_entry
mov x30, xzr
# ...and call __bionic_clone_entry with the 'fn' and 'arg' we stored on the child stack.
ldp x0, x1, [sp, #-16]
b __bionic_clone_entry