https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
Jakub Jelinek changed:
What|Removed |Added
Status|WAITING |RESOLVED
Resolution|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #17 from Dmitry Vyukov ---
Jakub, I guess you can close this.
Sorry again.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #16 from Dmitry Vyukov ---
> Could you please push that to the syzkaller tree [1] then?
Sorry, syzkaller page referred to outdated patch. I was hoping that Andrew will
take it soon, so that I can update the link to a more respected l
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #15 from Jiri Slaby ---
(In reply to Dmitry Vyukov from comment #14)
> If you apply the latest kcov patch "[PATCH v6] kernel: add kcov code
> coverage", it should work.
Could you please push that to the syzkaller tree [1] then?
[1]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #14 from Dmitry Vyukov ---
Wait, I already disabled instrumentation of hweight.c for because of this:
+# Kernel does not boot if we instrument this file as it uses custom calling
+# convention (see CONFIG_ARCH_HWEIGHT_CFLAGS).
+KCOV_
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #13 from Jakub Jelinek ---
Seems hweight.c is compiled with
-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx
-fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11
but that of course expects that all the
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #12 from Jiri Slaby ---
(In reply to Jiri Slaby from comment #11)
> __sw_hweight32 changes only retval (rax) and parameter (rdi).
... and rdi is stored to and restored from stack.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #11 from Jiri Slaby ---
(In reply to Jakub Jelinek from comment #10)
> If you are calling a function (__sw_hweight32) without letting gcc know you
> do that, are you sure that function call does not modify any registers other
> than "
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #10 from Jakub Jelinek ---
If you are calling a function (__sw_hweight32) without letting gcc know you do
that, are you sure that function call does not modify any registers other than
"flags" and "rax"?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #9 from Jiri Slaby ---
(In reply to Dmitry Vyukov from comment #8)
> First of all, are you sure that r12 is not 0 before the call?
Yes.
> Deference of 0xdc00 is how KASAN reacts on NULL deref, it does
> shadow check befo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #8 from Dmitry Vyukov ---
First of all, are you sure that r12 is not 0 before the call?
Deference of 0xdc00 is how KASAN reacts on NULL deref, it does
shadow check before the memory accesses. If original address is NULL,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #7 from Jiri Slaby ---
(In reply to Dmitry Vyukov from comment #6)
> Also what gcc version?
$ gcc-6 --version
gcc-6 (SUSE Linux) 6.0.0 20160121 (experimental) [trunk revision 232670]
> I've tried:
> gcc version 6.0.0 20160105 (exper
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #6 from Dmitry Vyukov ---
Also what gcc version?
I've tried:
gcc version 6.0.0 20160105 (experimental) (GCC)
$ gcc /tmp/af_netlink.c -c -O2 -fsanitize-coverage=trace-pc
-fsanitize=kernel-address --param asan-stack=1 --param asan-glo
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #5 from Jiri Slaby ---
(In reply to Jakub Jelinek from comment #4)
> What gcc options are you using on the preprocessed source to trigger this?
By default this:
gcc-6 -nostdinc -fno-strict-aliasing -fno-common -std=gnu89 -mno-sse -mn
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
Jakub Jelinek changed:
What|Removed |Added
Status|UNCONFIRMED |WAITING
Last reconfirmed|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #3 from Jiri Slaby ---
Preprocessed code:
http://www.fi.muni.cz/~xslaby/sklad/af_netlink.i
This one results in the code from initial description. I.e. rdx is loaded
before a call.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #2 from Jiri Slaby ---
Created attachment 37553
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37553&action=edit
__sanitizer_cov_trace_pc implementation
This guys actually changes rdx.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69624
--- Comment #1 from Jiri Slaby ---
Created attachment 37552
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37552&action=edit
__sw_hweight32 assembly
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