https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64963
Bug ID: 64963
Summary: IPA Cloning/Splitting does not copy function section
attributes resulting in kernel miscompilation
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: jgreenhalgh at gcc dot gnu.org
CC: hubicka at gcc dot gnu.org, jamborm at gcc dot gnu.org
Host: x86_64-unknown-linux-gnu
Target: aarch64-none-elf
Created attachment 34688
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34688&action=edit
Cloning fails to maintain section attributes on foo
When we create a clone for constant propagation, or in ipa-split,
we don't clone the section attribute for that function. For kernel
builds this can result in code ending up in the wrong section, resulting
in all sorts of carnage.
The testcase attached shows the issue for cloning (it is much harder
to engineer one for splitting, but the problem is analogous).
You can reproduce the bug with -O3. For AArch64 this gives:
.cpu generic+fp+simd
.file "ipa-clone-1.c"
.text
.align 2
.p2align 3,,7
.type foo.constprop.0, %function
foo.constprop.0:
mov w0, 35
ret
.size foo.constprop.0, .-foo.constprop.0
.align 2
.p2align 3,,7
.global bar
.type bar, %function
bar:
b foo.constprop.0
.size bar, .-bar
.ident "GCC: (unknown) 5.0.0 20150205 (experimental)"
Note that foo.constprop.0 is in the text section, while foo was declared with:
static int __attribute__ ((noinline section ("test_section")))
foo (int arg)
I would have expected to see:
.arch armv8-a+fp+simd
.file "ipa-clone-1.c"
.section test_section,"ax",%progbits
.align 2
.p2align 3,,7
.type foo.constprop.0, %function
foo.constprop.0:
mov w0, 35
ret
.size foo.constprop.0, .-foo.constprop.0
.text
.align 2
.p2align 3,,7
.global bar
.type bar, %function
bar:
b foo.constprop.0
.size bar, .-bar
.ident "GCC: (unknown) 5.0.0 20150205 (experimental)"
