From: Masami Hiramatsu (Google) mhiramat@kernel.org
commit 0fbcd8abf3375052cc7627cc53aba6f2eb189fbb upstream.
Mark arch_stack_walk() as noinstr instead of notrace and inline functions called from arch_stack_walk() as __always_inline so that user does not put any instrumentations on it, because this function can be used from return_address() which is used by lockdep.
Without this, if the kernel built with CONFIG_LOCKDEP=y, just probing arch_stack_walk() via <tracefs>/kprobe_events will crash the kernel on arm64.
# echo p arch_stack_walk >> ${TRACEFS}/kprobe_events # echo 1 > ${TRACEFS}/events/kprobes/enable kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name = arch_stack_walk, .offset = 0, .addr = arch_stack_walk+0x0/0x1c0 ------------[ 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_stack_walk, .offset = 0, .addr = arch_stack_walk+0x0/0x1c0 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! PREEMPT SMP Modules linked in: CPU: 0 PID: 17 Comm: migration/0 Tainted: G N 6.1.0-rc5+ #6 Hardware name: linux,dummy-virt (DT) Stopper: 0x0 <- 0x0 pstate: 600003c5 (nZCv DAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : kprobe_breakpoint_handler+0x178/0x17c lr : kprobe_breakpoint_handler+0x178/0x17c sp : ffff8000080d3090 x29: ffff8000080d3090 x28: ffff0df5845798c0 x27: ffffc4f59057a774 x26: ffff0df5ffbba770 x25: ffff0df58f420f18 x24: ffff49006f641000 x23: ffffc4f590579768 x22: ffff0df58f420f18 x21: ffff8000080d31c0 x20: ffffc4f590579768 x19: ffffc4f590579770 x18: 0000000000000006 x17: 5f6b636174735f68 x16: 637261203d207264 x15: 64612e202c30203d x14: 2074657366666f2e x13: 30633178302f3078 x12: 302b6b6c61775f6b x11: 636174735f686372 x10: ffffc4f590dc5bd8 x9 : ffffc4f58eb31958 x8 : 00000000ffffefff x7 : ffffc4f590dc5bd8 x6 : 80000000fffff000 x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : ffff0df5845798c0 x0 : 0000000000000064 Call trace: kprobes: Failed to recover from reentered kprobes. kprobes: Dump kprobe: .symbol_name = arch_stack_walk, .offset = 0, .addr = arch_stack_walk+0x0/0x1c0 ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/probes/kprobes.c:241!
Fixes: 39ef362d2d45 ("arm64: Make return_address() use arch_stack_walk()") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Acked-by: Mark Rutland mark.rutland@arm.com Link: https://lore.kernel.org/r/166994751368.439920.3236636557520824664.stgit@devn... Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/stacktrace.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
--- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -23,8 +23,8 @@ * * The regs must be on a stack currently owned by the calling task. */ -static inline void unwind_init_from_regs(struct unwind_state *state, - struct pt_regs *regs) +static __always_inline void unwind_init_from_regs(struct unwind_state *state, + struct pt_regs *regs) { unwind_init_common(state, current);
@@ -58,8 +58,8 @@ static __always_inline void unwind_init_ * duration of the unwind, or the unwind will be bogus. It is never valid to * call this for the current task. */ -static inline void unwind_init_from_task(struct unwind_state *state, - struct task_struct *task) +static __always_inline void unwind_init_from_task(struct unwind_state *state, + struct task_struct *task) { unwind_init_common(state, task);
@@ -186,7 +186,7 @@ void show_stack(struct task_struct *tsk, : stackinfo_get_unknown(); \ })
-noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, +noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, struct task_struct *task, struct pt_regs *regs) {