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Sat, 28 Jun 2025 13:26:39 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id SOtpdDiBEncU; Sat, 28 Jun 2025 13:26:39 +0200 (CEST) Received: from [192.168.202.221] (unknown [192.168.202.221]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 93EA18B763; Sat, 28 Jun 2025 13:26:35 +0200 (CEST) Message-ID: Date: Sat, 28 Jun 2025 13:26:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/11] kasan: unify kasan_arch_is_ready with kasan_enabled To: Sabyrzhan Tasbolatov , ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, chris@zankel.net, jcmvbkbc@gmail.com, akpm@linux-foundation.org, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, justinstitt@google.com Cc: arnd@arndb.de, rppt@kernel.org, geert@linux-m68k.org, mcgrof@kernel.org, guoweikang.kernel@gmail.com, tiwei.btw@antgroup.com, kevin.brodsky@arm.com, benjamin.berg@intel.com, kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, linux-mm@kvack.org, llvm@lists.linux.dev References: <20250626153147.145312-1-snovitoll@gmail.com> Content-Language: fr-FR From: Christophe Leroy In-Reply-To: <20250626153147.145312-1-snovitoll@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250628_045038_811324_AE877C89 X-CRM114-Status: GOOD ( 31.83 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org Le 26/06/2025 à 17:31, Sabyrzhan Tasbolatov a écrit : > This patch series unifies the kasan_arch_is_ready() and kasan_enabled() > interfaces by extending the existing kasan_enabled() infrastructure to > work consistently across all KASAN modes (Generic, SW_TAGS, HW_TAGS). > > Currently, kasan_enabled() only works for HW_TAGS mode using a static key, > while other modes either return IS_ENABLED(CONFIG_KASAN) (compile-time > constant) or rely on architecture-specific kasan_arch_is_ready() > implementations with custom static keys and global variables. > > This leads to: > - Code duplication across architectures > - Inconsistent runtime behavior between KASAN modes > - Architecture-specific readiness tracking You should also consider refactoring ARCH_DISABLE_KASAN_INLINE, there is a high dependency between deferring KASAN readiness and not supporting inline KASAN. > > After this series: > - All KASAN modes use the same kasan_flag_enabled static key > - Consistent runtime enable/disable behavior across modes > - Simplified architecture code with unified kasan_init_generic() calls > - Elimination of arch specific kasan_arch_is_ready() implementations > - Unified vmalloc integration using kasan_enabled() checks I dislike that modes which can be enabled from the very begining now also depends on the static key being enabled later. The size is increased for no valid reason: $ size vmlinux.kasan* text data bss dec hex filename 13965336 6716942 494912 21177190 1432366 vmlinux.kasan0 ==> outline KASAN before your patch 13965496 6718422 494944 21178862 14329ee vmlinux.kasan1 ==> outline KASAN after your patch 13965336 6716942 494912 21177190 1432366 vmlinux.kasan2 ==> outline KASAN after your patch + below change 32517472 6716958 494912 39729342 25e38be vmlinux.kasani0 ==> inline KASAN before your patch 32518848 6718438 494944 39732230 25e4406 vmlinux.kasani1 ==> inline KASAN after your patch 32517536 6716958 494912 39729406 25e38fe vmlinux.kasani2 ==> inline KASAN after your patch + below change Below change (atop you series) only makes use of static key when needed: diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index c3e0cc83f120..7a8e5db603cc 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -122,6 +122,7 @@ config PPC # Please keep this list sorted alphabetically. # select ARCH_32BIT_OFF_T if PPC32 + select ARCH_DEFER_KASAN if PPC_RADIX_MMU select ARCH_DISABLE_KASAN_INLINE if PPC_RADIX_MMU select ARCH_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE select ARCH_ENABLE_MEMORY_HOTPLUG @@ -219,7 +220,7 @@ config PPC select HAVE_ARCH_JUMP_LABEL select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_KASAN if PPC32 && PAGE_SHIFT <= 14 - select HAVE_ARCH_KASAN if PPC_RADIX_MMU + select HAVE_ARCH_KASAN_DEFERED if PPC_RADIX_MMU select HAVE_ARCH_KASAN if PPC_BOOK3E_64 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN select HAVE_ARCH_KCSAN diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h index 2436eb45cfee..fda86e77fe4f 100644 --- a/include/linux/kasan-enabled.h +++ b/include/linux/kasan-enabled.h @@ -4,7 +4,7 @@ #include -#ifdef CONFIG_KASAN +#ifdef CONFIG_KASAN_DEFER /* * Global runtime flag. Starts ‘false’; switched to ‘true’ by @@ -17,13 +17,21 @@ static __always_inline bool kasan_enabled(void) return static_branch_likely(&kasan_flag_enabled); } -#else /* !CONFIG_KASAN */ +static inline void kasan_enable(void) +{ + static_branch_enable(&kasan_flag_enabled); +} + +#else /* !CONFIG_KASAN_DEFER */ static __always_inline bool kasan_enabled(void) { - return false; + return IS_ENABLED(CONFIG_KASAN); } +static inline void kasan_enable(void) +{ +} #endif /* CONFIG_KASAN */ #ifdef CONFIG_KASAN_HW_TAGS diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index f82889a830fa..e0c300f55c07 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -13,6 +13,9 @@ config HAVE_ARCH_KASAN_HW_TAGS config HAVE_ARCH_KASAN_VMALLOC bool +config ARCH_DEFER_KASAN + bool + config ARCH_DISABLE_KASAN_INLINE bool help @@ -58,6 +61,9 @@ config CC_HAS_KASAN_MEMINTRINSIC_PREFIX help The compiler is able to prefix memintrinsics with __asan or __hwasan. +config KASAN_DIFER + def_bool ARCH_DIFER_KASAN + choice prompt "KASAN mode" default KASAN_GENERIC diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 0f3648335a6b..01f56eed9d20 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -36,8 +36,10 @@ * Definition of the unified static key declared in kasan-enabled.h. * This provides consistent runtime enable/disable across all KASAN modes. */ +#ifdef CONFIG_KASAN_DEFER DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled); EXPORT_SYMBOL(kasan_flag_enabled); +#endif struct slab *kasan_addr_to_slab(const void *addr) { diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index a3b112868be7..516b49accc4f 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -42,7 +42,7 @@ */ void __init kasan_init_generic(void) { - static_branch_enable(&kasan_flag_enabled); + kasan_enable(); pr_info("KernelAddressSanitizer initialized (generic)\n"); } diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 8e819fc4a260..c8289a3feabf 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -253,7 +253,7 @@ void __init kasan_init_hw_tags(void) kasan_init_tags(); /* KASAN is now initialized, enable it. */ - static_branch_enable(&kasan_flag_enabled); + kasan_enable(); pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, vmalloc=%s, stacktrace=%s)\n", kasan_mode_info(), diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c index 525bc91e2fcd..275bcbbf6120 100644 --- a/mm/kasan/sw_tags.c +++ b/mm/kasan/sw_tags.c @@ -45,7 +45,7 @@ void __init kasan_init_sw_tags(void) kasan_init_tags(); - static_branch_enable(&kasan_flag_enabled); + kasan_enable(); pr_info("KernelAddressSanitizer initialized (sw-tags, stacktrace=%s)\n", str_on_off(kasan_stack_collection_enabled())); > > This addresses the bugzilla issue [1] about making > kasan_flag_enabled and kasan_enabled() work for Generic mode, > and extends it to provide true unification across all modes. > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=217049 > > === Current mainline KUnit status > > To see if there is any regression, I've tested first on the following > commit 739a6c93cc75 ("Merge tag 'nfsd-6.16-1' of > git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux"). > > Tested via compiling a kernel with CONFIG_KASAN_KUNIT_TEST and running > QEMU VM. There are failing tests in SW_TAGS and GENERIC modes in arm64: > > arm64 CONFIG_KASAN_HW_TAGS: > # kasan: pass:62 fail:0 skip:13 total:75 > # Totals: pass:62 fail:0 skip:13 total:75 > ok 1 kasan > > arm64 CONFIG_KASAN_SW_TAGS=y: > # kasan: pass:65 fail:1 skip:9 total:75 > # Totals: pass:65 fail:1 skip:9 total:75 > not ok 1 kasan > # kasan_strings: EXPECTATION FAILED at mm/kasan/kasan_test_c.c:1598 > KASAN failure expected in "strscpy(ptr, src + KASAN_GRANULE_SIZE, KASAN_GRANULE_SIZE)", but none occurred > > arm64 CONFIG_KASAN_GENERIC=y, CONFIG_KASAN_OUTLINE=y: > # kasan: pass:61 fail:1 skip:13 total:75 > # Totals: pass:61 fail:1 skip:13 total:75 > not ok 1 kasan > # same failure as above > > x86_64 CONFIG_KASAN_GENERIC=y: > # kasan: pass:58 fail:0 skip:17 total:75 > # Totals: pass:58 fail:0 skip:17 total:75 > ok 1 kasan > > === Testing with patches > > Testing in v2: > > - Compiled every affected arch with no errors: > > $ make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \ > OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \ > HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld \ > ARCH=$ARCH > > $ clang --version > ClangBuiltLinux clang version 19.1.4 > Target: x86_64-unknown-linux-gnu > Thread model: posix > > - make ARCH=um produces the warning during compiling: > MODPOST Module.symvers > WARNING: modpost: vmlinux: section mismatch in reference: \ > kasan_init+0x43 (section: .ltext) -> \ > kasan_init_generic (section: .init.text) > > AFAIU, it's due to the code in arch/um/kernel/mem.c, where kasan_init() > is placed in own section ".kasan_init", which calls kasan_init_generic() > which is marked with "__init". > > - Booting via qemu-system- and running KUnit tests: > > * arm64 (GENERIC, HW_TAGS, SW_TAGS): no regression, same above results. > * x86_64 (GENERIC): no regression, no errors > > === NB > > I haven't tested the kernel boot on the following arch. due to the absence > of qemu-system- support on those arch on my machine, so I defer this to > relevant arch people to test KASAN initialization: > - loongarch > - s390 > - um > - xtensa > - powerpc > - riscv > > Code changes in v2: > - Replace the order of patches. Move "kasan: replace kasan_arch_is_ready > with kasan_enabled" at the end to keep the compatibility. > - arch/arm, arch/riscv: add 2 arch. missed in v1 > - arch/powerpc: add kasan_init_generic() in other kasan_init() calls: > arch/powerpc/mm/kasan/init_32.c > arch/powerpc/mm/kasan/init_book3e_64.c > - arch/um: add the proper header `#include `. Tested > via compiling with no errors. In the v1 arch/um changes were acked-by > Johannes Berg, though I don't include it due to the changed code in v2. > - arch/powerpc: add back `#ifdef CONFIG_KASAN` deleted in v1 and tested > the compilation. > - arch/loongarch: update git commit message about non-standard flow of > calling kasan_init_generic() > > Sabyrzhan Tasbolatov (11): > kasan: unify static kasan_flag_enabled across modes > kasan/arm64: call kasan_init_generic in kasan_init > kasan/arm: call kasan_init_generic in kasan_init > kasan/xtensa: call kasan_init_generic in kasan_init > kasan/loongarch: call kasan_init_generic in kasan_init > kasan/um: call kasan_init_generic in kasan_init > kasan/x86: call kasan_init_generic in kasan_init > kasan/s390: call kasan_init_generic in kasan_init > kasan/powerpc: call kasan_init_generic in kasan_init > kasan/riscv: call kasan_init_generic in kasan_init > kasan: replace kasan_arch_is_ready with kasan_enabled > > arch/arm/mm/kasan_init.c | 2 +- > arch/arm64/mm/kasan_init.c | 4 +--- > arch/loongarch/include/asm/kasan.h | 7 ------- > arch/loongarch/mm/kasan_init.c | 7 ++----- > arch/powerpc/include/asm/kasan.h | 13 ------------- > arch/powerpc/mm/kasan/init_32.c | 2 +- > arch/powerpc/mm/kasan/init_book3e_64.c | 2 +- > arch/powerpc/mm/kasan/init_book3s_64.c | 6 +----- > arch/riscv/mm/kasan_init.c | 1 + > arch/s390/kernel/early.c | 3 ++- > arch/um/include/asm/kasan.h | 5 ----- > arch/um/kernel/mem.c | 4 ++-- > arch/x86/mm/kasan_init_64.c | 2 +- > arch/xtensa/mm/kasan_init.c | 2 +- > include/linux/kasan-enabled.h | 22 ++++++++++++++++------ > include/linux/kasan.h | 6 ++++++ > mm/kasan/common.c | 15 +++++++++++---- > mm/kasan/generic.c | 17 ++++++++++++++--- > mm/kasan/hw_tags.c | 7 ------- > mm/kasan/kasan.h | 6 ------ > mm/kasan/shadow.c | 15 +++------------ > mm/kasan/sw_tags.c | 2 ++ > 22 files changed, 66 insertions(+), 84 deletions(-) >