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[54.240.197.231]) by smtp.gmail.com with ESMTPSA id m17-20020a05600c4f5100b00412b7456ef7sm3506412wmq.5.2024.02.29.15.16.46 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Feb 2024 15:16:46 -0800 (PST) From: Puranjay Mohan To: catalin.marinas@arm.com, will@kernel.org, nathan@kernel.org, mark.rutland@arm.com, broonie@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Cc: puranjay12@gmail.com Subject: [PATCH] arm64: prohibit probing on arch_kunwind_consume_entry() Date: Thu, 29 Feb 2024 23:16:20 +0000 Message-Id: <20240229231620.24846-1-puranjay12@gmail.com> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Make arch_kunwind_consume_entry() as __always_inline otherwise the compiler might not inline it and allow attaching probes to it. Without this, just probing arch_kunwind_consume_entry() via /kprobe_events will crash the kernel on arm64. The crash can be reproduced using the following compiler and kernel combination: clang version 19.0.0git (https://github.com/llvm/llvm-project.git d68d29516102252f6bf6dc23fb22cef144ca1cb3) commit 87adedeba51a ("Merge tag 'net-6.8-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net") [root@localhost ~]# echo 'p arch_kunwind_consume_entry' > /sys/kernel/debug/tracing/kprobe_events [root@localhost ~]# echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable Modules linked in: aes_ce_blk aes_ce_cipher ghash_ce sha2_ce virtio_net sha256_arm64 sha1_ce arm_smccc_trng net_failover failover virtio_mmio uio_pdrv_genirq uio sch_fq_codel dm_mod dax configfs CPU: 3 PID: 1405 Comm: bash Not tainted 6.8.0-rc6+ #14 Hardware name: linux,dummy-virt (DT) pstate: 604003c5 (nZCv DAIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : kprobe_breakpoint_handler+0x17c/0x258 lr : kprobe_breakpoint_handler+0x17c/0x258 sp : ffff800085d6ab60 x29: ffff800085d6ab60 x28: ffff0000066f0040 x27: ffff0000066f0b20 x26: ffff800081fa7b0c x25: 0000000000000002 x24: ffff00000b29bd18 x23: ffff00007904c590 x22: ffff800081fa6590 x21: ffff800081fa6588 x20: ffff00000b29bd18 x19: ffff800085d6ac40 x18: 0000000000000079 x17: 0000000000000001 x16: ffffffffffffffff x15: 0000000000000004 x14: ffff80008277a940 x13: 0000000000000003 x12: 0000000000000003 x11: 00000000fffeffff x10: c0000000fffeffff x9 : aa95616fdf80cc00 x8 : aa95616fdf80cc00 x7 : 205d343137373231 x6 : ffff800080fb48ec x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000 x2 : 0000000000000000 x1 : ffff800085d6a910 x0 : 0000000000000079 Call trace: kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name = arch_kunwind_consume_entry, .offset = 0, .addr = arch_kunwind_consume_entry+0x0/0x40 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name = arch_kunwind_consume_entry, .offset = 0, .addr = arch_kunwind_consume_entry+0x0/0x40 Fixes: 1aba06e7b2b49 ("arm64: stacktrace: factor out kunwind_stack_walk()") Signed-off-by: Puranjay Mohan --- arch/arm64/kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 7f88028a00c0..b2a60e0bcfd2 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -247,7 +247,7 @@ struct kunwind_consume_entry_data { void *cookie; }; -static bool +static __always_inline bool arch_kunwind_consume_entry(const struct kunwind_state *state, void *cookie) { struct kunwind_consume_entry_data *data = cookie; base-commit: 87adedeba51a822533649b143232418b9e26d08b -- 2.40.1