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Message-ID: <CACzwLxj3WLTK+A7YLcYvg5ZwvQdvoBuZL3bmEF+ELinFZgU=Pg@mail.gmail.com>
Date: Thu, 26 Jun 2025 18:52:53 +0500
From: Sabyrzhan Tasbolatov <snovitoll@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com,
dvyukov@...gle.com, vincenzo.frascino@....com, catalin.marinas@....com,
will@...nel.org, chenhuacai@...nel.org, kernel@...0n.name,
maddy@...ux.ibm.com, mpe@...erman.id.au, npiggin@...il.com,
christophe.leroy@...roup.eu, hca@...ux.ibm.com, gor@...ux.ibm.com,
agordeev@...ux.ibm.com, borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
richard@....at, anton.ivanov@...bridgegreys.com, johannes@...solutions.net,
dave.hansen@...ux.intel.com, luto@...nel.org, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
chris@...kel.net, jcmvbkbc@...il.com, akpm@...ux-foundation.org,
guoweikang.kernel@...il.com, geert@...ux-m68k.org, rppt@...nel.org,
tiwei.btw@...group.com, richard.weiyang@...il.com, benjamin.berg@...el.com,
kevin.brodsky@....com, kasan-dev@...glegroups.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
loongarch@...ts.linux.dev, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, linux-um@...ts.infradead.org, linux-mm@...ck.org
Subject: Re: [PATCH 5/9] kasan/loongarch: call kasan_init_generic in kasan_init
On Thu, Jun 26, 2025 at 6:29 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Wed, Jun 25, 2025 at 02:52:20PM +0500, Sabyrzhan Tasbolatov wrote:
> > Call kasan_init_generic() which enables the static flag
> > to mark generic KASAN initialized, otherwise it's an inline stub.
> >
> > Replace `kasan_arch_is_ready` with `kasan_enabled`.
> > Delete the flag `kasan_early_stage` in favor of the global static key
> > enabled via kasan_enabled().
> >
> > printk banner is printed earlier right where `kasan_early_stage`
> > was flipped, just to keep the same flow.
> >
> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218315
> > Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
> > ---
> > arch/loongarch/include/asm/kasan.h | 7 -------
> > arch/loongarch/mm/kasan_init.c | 7 ++-----
> > 2 files changed, 2 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/loongarch/include/asm/kasan.h b/arch/loongarch/include/asm/kasan.h
> > index 7f52bd31b9d..b0b74871257 100644
> > --- a/arch/loongarch/include/asm/kasan.h
> > +++ b/arch/loongarch/include/asm/kasan.h
> > @@ -66,7 +66,6 @@
> > #define XKPRANGE_WC_SHADOW_OFFSET (KASAN_SHADOW_START + XKPRANGE_WC_KASAN_OFFSET)
> > #define XKVRANGE_VC_SHADOW_OFFSET (KASAN_SHADOW_START + XKVRANGE_VC_KASAN_OFFSET)
> >
> > -extern bool kasan_early_stage;
> > extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
> >
> > #define kasan_mem_to_shadow kasan_mem_to_shadow
> > @@ -75,12 +74,6 @@ void *kasan_mem_to_shadow(const void *addr);
> > #define kasan_shadow_to_mem kasan_shadow_to_mem
> > const void *kasan_shadow_to_mem(const void *shadow_addr);
> >
> > -#define kasan_arch_is_ready kasan_arch_is_ready
> > -static __always_inline bool kasan_arch_is_ready(void)
> > -{
> > - return !kasan_early_stage;
> > -}
> > -
> > #define addr_has_metadata addr_has_metadata
> > static __always_inline bool addr_has_metadata(const void *addr)
> > {
> > diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
> > index d2681272d8f..cf8315f9119 100644
> > --- a/arch/loongarch/mm/kasan_init.c
> > +++ b/arch/loongarch/mm/kasan_init.c
> > @@ -40,11 +40,9 @@ static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
> > #define __pte_none(early, pte) (early ? pte_none(pte) : \
> > ((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
> >
> > -bool kasan_early_stage = true;
> > -
> > void *kasan_mem_to_shadow(const void *addr)
> > {
> > - if (!kasan_arch_is_ready()) {
> > + if (!kasan_enabled()) {
> > return (void *)(kasan_early_shadow_page);
> > } else {
> > unsigned long maddr = (unsigned long)addr;
> > @@ -298,7 +296,7 @@ void __init kasan_init(void)
> > kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
> > kasan_mem_to_shadow((void *)KFENCE_AREA_END));
> >
> > - kasan_early_stage = false;
> > + kasan_init_generic();
> >
> > /* Populate the linear mapping */
> > for_each_mem_range(i, &pa_start, &pa_end) {
> > @@ -329,5 +327,4 @@ void __init kasan_init(void)
> >
> > /* At this point kasan is fully initialized. Enable error messages */
> > init_task.kasan_depth = 0;
> > - pr_info("KernelAddressSanitizer initialized.\n");
> > }
>
> This one is weird because its the only arch that does things after
> marking early_state false.
>
> Is that really correct, or should kasan_init_generic() be last, like all
> the other architectures?
It really differs from other arch kasan_init(). I can't verify that
kasan_init_generic()
can be placed at the end of kasan_init() because right after
switching the KASAN flag, there's kasan_enabled() check in
kasan_mem_to_shadow().
In arch/loongarch/mm/kasan_init.c:
void *kasan_mem_to_shadow(const void *addr)
{
if (!kasan_enabled()) {
return (void *)(kasan_early_shadow_page);
} else {
...
}
void __init kasan_init(void)
{
...
kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
kasan_mem_to_shadow((void *)KFENCE_AREA_END));
kasan_init_generic();
/* Populate the linear mapping */
for_each_mem_range(i, &pa_start, &pa_end) {
....
kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
}
>
> Also, please move init_task.kasan_depth = 0 into the generic thing.
> ARM64 might have fooled you with the wrapper function, but they all do
> this right before that pr_info you're taking out.
Please check "[PATCH 1/9] kasan: unify static kasan_flag_enabled across modes",
where I've replied to Christophe:
https://lore.kernel.org/all/CACzwLxj3KWdy-mBu-te1OFf2FZ8eTp5CieYswF5NVY4qPWD93Q@mail.gmail.com/
I can try to put `init_task.kasan_depth = 0;` in kasan_init_generic(),
but in ARM64 kasan_init() we'll still need to have this line for
HW_TAGS, SW_TAGS mode.
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