From 2c79bd34af13de221ddab29d8dfc9d5eeca8fe9b Mon Sep 17 00:00:00 2001 From: Puranjay Mohan Date: Thu, 29 Feb 2024 23:16:20 +0000 Subject: arm64: prohibit probing on arch_kunwind_consume_entry() 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: 1aba06e7b2b4 ("arm64: stacktrace: factor out kunwind_stack_walk()") Signed-off-by: Puranjay Mohan Reviewed-by: Mark Rutland Link: https://lore.kernel.org/r/20240229231620.24846-1-puranjay12@gmail.com Signed-off-by: Will Deacon --- arch/arm64/kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') 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; -- cgit