Hi Nathan,
Le 14/10/2021 à 18:55, Nathan Chancellor a écrit :
On Fri, Oct 08, 2021 at 11:46:55AM -0700, Palmer Dabbelt wrote:
On Thu, 23 Sep 2021 07:59:46 PDT (-0700), nathan@xxxxxxxxxx wrote:
On Thu, Sep 23, 2021 at 12:07:17PM +0200, Marco Elver wrote:
On Wed, 22 Sept 2021 at 22:55, Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
Currently, the asan-stack parameter is only passed along if
CFLAGS_KASAN_SHADOW is not empty, which requires KASAN_SHADOW_OFFSET to
be defined in Kconfig so that the value can be checked. In RISC-V's
case, KASAN_SHADOW_OFFSET is not defined in Kconfig, which means that
asan-stack does not get disabled with clang even when CONFIG_KASAN_STACK
is disabled, resulting in large stack warnings with allmodconfig:
drivers/video/fbdev/omap2/omapfb/displays/panel-lgphilips-lb035q02.c:117:12:
error: stack frame size (14400) exceeds limit (2048) in function
'lb035q02_connect' [-Werror,-Wframe-larger-than]
static int lb035q02_connect(struct omap_dss_device *dssdev)
^
1 error generated.
Ensure that the value of CONFIG_KASAN_STACK is always passed along to
the compiler so that these warnings do not happen when
CONFIG_KASAN_STACK is disabled.
Link: https://github.com/ClangBuiltLinux/linux/issues/1453
References: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier")
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Thanks!
[ Which tree are you planning to take it through? ]
Gah, I was intending for it to go through -mm, then I cc'd neither
Andrew nor linux-mm... :/ Andrew, do you want me to resend or can you
grab it from LKML?
Acked-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
(assuming you still want it through somewhere else)
Thanks, it is now in mainline as commit 19532869feb9 ("kasan: always
respect CONFIG_KASAN_STACK").
Note, arch/riscv/include/asm/kasan.h mentions KASAN_SHADOW_OFFSET in
comment (copied from arm64). Did RISC-V just forget to copy over the
Kconfig option?
I do see it defined in that file as well but you are right that they did
not copy the Kconfig logic, even though it was present in the tree when
RISC-V KASAN was implemented. Perhaps they should so that they get
access to the other flags in the "else" branch?
Ya, looks like we just screwed this up. I'm seeing some warnings like
cc1: warning: ‘-fsanitize=kernel-address’ with stack protection is not supported without ‘-fasan-shadow-offset=’ for this target
Hmmm, I thought I did a GCC build with this change but I must not have
:/
which is how I ended up here, I'm assuming that's what you're talking about
here? LMK if you were planning on sending along a fix or if you want me to
go figure it out.
I took a look at moving the logic into Kconfig like arm64 before sending
this change and I did not really understand it well enough to do so. I
think it would be best if you were able to do that so that nothing gets
messed up.
I'll do it tomorrow, I'm the last one who touched kasan on riscv :)
Thanks,
Alex
Cheers,
Nathan
_______________________________________________
linux-riscv mailing list
linux-riscv@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/linux-riscv
