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* [Bug target/99836] New: aarch64: -fpatchable-function-entry=N[,0] should place .cfi_startproc before NOPs
@ 2021-03-30 18:20 i at maskray dot me
2021-03-31 10:21 ` [Bug target/99836] " rearnsha at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: i at maskray dot me @ 2021-03-30 18:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99836
Bug ID: 99836
Summary: aarch64: -fpatchable-function-entry=N[,0] should place
.cfi_startproc before NOPs
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: i at maskray dot me
Target Milestone: ---
Extracted from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92424#c8
% echo 'int main() {}' > a.c
% clang --target=aarch64 -fpatchable-function-entry=2
-mbranch-protection=standard -S a.c -o -
...
main: // @main
.Lfunc_begin0:
.cfi_startproc
// %bb.0: // %entry
hint #34
.Lpatch0:
nop
nop
%
/tmp/glibc-many/install/compilers/aarch64-linux-gnu/bin/aarch64-glibc-linux-gnu-g++
-fpatchable-function-entry=2 -mbranch-protection=standard -S a.c -o -
.arch armv8-a
.file "a.c"
.text
.align 2
.global main
.type main, %function
main:
hint 34 // bti c
.section __patchable_function_entries,"aw",@progbits
.align 3
.8byte .LPFE1
.text
.LPFE1:
nop
nop
.LFB0:
.cfi_startproc
For -fpatchable-function-entry=N[,0], placing .cfi_startproc before NOPs makes
more sense and can make unwinding work in that region.
For N[,M] where M>0, that is a very narrow use case by the Linux kernel. I
prefer not to place .cfi_startproc above the function label.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug target/99836] aarch64: -fpatchable-function-entry=N[,0] should place .cfi_startproc before NOPs
2021-03-30 18:20 [Bug target/99836] New: aarch64: -fpatchable-function-entry=N[,0] should place .cfi_startproc before NOPs i at maskray dot me
@ 2021-03-31 10:21 ` rearnsha at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: rearnsha at gcc dot gnu.org @ 2021-03-31 10:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99836
Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Dup
*** This bug has been marked as a duplicate of bug 98776 ***
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-03-30 18:20 [Bug target/99836] New: aarch64: -fpatchable-function-entry=N[,0] should place .cfi_startproc before NOPs i at maskray dot me
2021-03-31 10:21 ` [Bug target/99836] " rearnsha at gcc dot gnu.org
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