From 7e7df71fd57ff2894d96abb0080922bf39460a79 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Thu, 14 Jun 2018 14:58:21 -0400 Subject: arm64: fix infinite stacktrace I've got this infinite stacktrace when debugging another problem: [ 908.795225] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 908.796176] 1-...!: (1 GPs behind) idle=952/1/4611686018427387904 softirq=1462/1462 fqs=355 [ 908.797692] 2-...!: (1 GPs behind) idle=f42/1/4611686018427387904 softirq=1550/1551 fqs=355 [ 908.799189] (detected by 0, t=2109 jiffies, g=130, c=129, q=235) [ 908.800284] Task dump for CPU 1: [ 908.800871] kworker/1:1 R running task 0 32 2 0x00000022 [ 908.802127] Workqueue: writecache-writeabck writecache_writeback [dm_writecache] [ 908.820285] Call trace: [ 908.824785] __switch_to+0x68/0x90 [ 908.837661] 0xfffffe00603afd90 [ 908.844119] 0xfffffe00603afd90 [ 908.850091] 0xfffffe00603afd90 [ 908.854285] 0xfffffe00603afd90 [ 908.863538] 0xfffffe00603afd90 [ 908.865523] 0xfffffe00603afd90 The machine just locked up and kept on printing the same line over and over again. This patch fixes it. Signed-off-by: Mikulas Patocka Signed-off-by: Will Deacon --- arch/arm64/kernel/stacktrace.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm64/kernel/stacktrace.c') diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d5718a060672..e160ca123da3 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -56,6 +56,9 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); + if (frame->fp <= fp) + return -EINVAL; + #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && (frame->pc == (unsigned long)return_to_handler)) { -- cgit v1.2.3 From e87a4a92fba3721eb06ba8d061b550e09e3d063a Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 12 Jul 2018 11:37:40 +0100 Subject: Revert "arm64: fix infinite stacktrace" This reverts commit 7e7df71fd57ff2894d96abb0080922bf39460a79. When unwinding out of the IRQ stack and onto the interrupted EL1 stack, we cannot rely on the frame pointer being strictly increasing, as this could terminate the backtrace early depending on how the stacks have been allocated. Signed-off-by: Will Deacon --- arch/arm64/kernel/stacktrace.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/arm64/kernel/stacktrace.c') diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index e160ca123da3..d5718a060672 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -56,9 +56,6 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); - if (frame->fp <= fp) - return -EINVAL; - #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && (frame->pc == (unsigned long)return_to_handler)) { -- cgit v1.2.3 From 8a1ccfbc9e0256baafbbce85ccdb72ec89af2aab Mon Sep 17 00:00:00 2001 From: Laura Abbott Date: Fri, 20 Jul 2018 14:41:53 -0700 Subject: arm64: Add stack information to on_accessible_stack In preparation for enabling the stackleak plugin on arm64, we need a way to get the bounds of the current stack. Extend on_accessible_stack to get this information. Acked-by: Alexander Popov Reviewed-by: Mark Rutland Signed-off-by: Laura Abbott [will: folded in fix for allmodconfig build breakage w/ sdei] Signed-off-by: Will Deacon --- arch/arm64/include/asm/sdei.h | 9 +++-- arch/arm64/include/asm/stacktrace.h | 73 +++++++++++++++++++++++++++++++------ arch/arm64/kernel/ptrace.c | 2 +- arch/arm64/kernel/sdei.c | 51 +++++++++++++++++++++----- arch/arm64/kernel/stacktrace.c | 2 +- 5 files changed, 111 insertions(+), 26 deletions(-) (limited to 'arch/arm64/kernel/stacktrace.c') diff --git a/arch/arm64/include/asm/sdei.h b/arch/arm64/include/asm/sdei.h index e073e6886685..ffe47d766c25 100644 --- a/arch/arm64/include/asm/sdei.h +++ b/arch/arm64/include/asm/sdei.h @@ -40,15 +40,18 @@ asmlinkage unsigned long __sdei_handler(struct pt_regs *regs, unsigned long sdei_arch_get_entry_point(int conduit); #define sdei_arch_get_entry_point(x) sdei_arch_get_entry_point(x) -bool _on_sdei_stack(unsigned long sp); -static inline bool on_sdei_stack(unsigned long sp) +struct stack_info; + +bool _on_sdei_stack(unsigned long sp, struct stack_info *info); +static inline bool on_sdei_stack(unsigned long sp, + struct stack_info *info) { if (!IS_ENABLED(CONFIG_VMAP_STACK)) return false; if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE)) return false; if (in_nmi()) - return _on_sdei_stack(sp); + return _on_sdei_stack(sp, info); return false; } diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index 902f9edacbea..e86737b7c924 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -32,6 +32,21 @@ struct stackframe { #endif }; +enum stack_type { + STACK_TYPE_UNKNOWN, + STACK_TYPE_TASK, + STACK_TYPE_IRQ, + STACK_TYPE_OVERFLOW, + STACK_TYPE_SDEI_NORMAL, + STACK_TYPE_SDEI_CRITICAL, +}; + +struct stack_info { + unsigned long low; + unsigned long high; + enum stack_type type; +}; + extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame); extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame, int (*fn)(struct stackframe *, void *), void *data); @@ -39,7 +54,8 @@ extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk); DECLARE_PER_CPU(unsigned long *, irq_stack_ptr); -static inline bool on_irq_stack(unsigned long sp) +static inline bool on_irq_stack(unsigned long sp, + struct stack_info *info) { unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr); unsigned long high = low + IRQ_STACK_SIZE; @@ -47,46 +63,79 @@ static inline bool on_irq_stack(unsigned long sp) if (!low) return false; - return (low <= sp && sp < high); + if (sp < low || sp >= high) + return false; + + if (info) { + info->low = low; + info->high = high; + info->type = STACK_TYPE_IRQ; + } + + return true; } -static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp) +static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp, + struct stack_info *info) { unsigned long low = (unsigned long)task_stack_page(tsk); unsigned long high = low + THREAD_SIZE; - return (low <= sp && sp < high); + if (sp < low || sp >= high) + return false; + + if (info) { + info->low = low; + info->high = high; + info->type = STACK_TYPE_TASK; + } + + return true; } #ifdef CONFIG_VMAP_STACK DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack); -static inline bool on_overflow_stack(unsigned long sp) +static inline bool on_overflow_stack(unsigned long sp, + struct stack_info *info) { unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack); unsigned long high = low + OVERFLOW_STACK_SIZE; - return (low <= sp && sp < high); + if (sp < low || sp >= high) + return false; + + if (info) { + info->low = low; + info->high = high; + info->type = STACK_TYPE_OVERFLOW; + } + + return true; } #else -static inline bool on_overflow_stack(unsigned long sp) { return false; } +static inline bool on_overflow_stack(unsigned long sp, + struct stack_info *info) { return false; } #endif + /* * We can only safely access per-cpu stacks from current in a non-preemptible * context. */ -static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp) +static inline bool on_accessible_stack(struct task_struct *tsk, + unsigned long sp, + struct stack_info *info) { - if (on_task_stack(tsk, sp)) + if (on_task_stack(tsk, sp, info)) return true; if (tsk != current || preemptible()) return false; - if (on_irq_stack(sp)) + if (on_irq_stack(sp, info)) return true; - if (on_overflow_stack(sp)) + if (on_overflow_stack(sp, info)) return true; - if (on_sdei_stack(sp)) + if (on_sdei_stack(sp, info)) return true; return false; diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 299758f9b9c4..6219486fa25f 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -132,7 +132,7 @@ static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) { return ((addr & ~(THREAD_SIZE - 1)) == (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) || - on_irq_stack(addr); + on_irq_stack(addr, NULL); } /** diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c index 6b8d90d5ceae..a94a868f0532 100644 --- a/arch/arm64/kernel/sdei.c +++ b/arch/arm64/kernel/sdei.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include @@ -88,23 +89,55 @@ static int init_sdei_stacks(void) return err; } -bool _on_sdei_stack(unsigned long sp) +bool on_sdei_normal_stack(unsigned long sp, + struct stack_info *info) { - unsigned long low, high; + unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr); + unsigned long high = low + SDEI_STACK_SIZE; - if (!IS_ENABLED(CONFIG_VMAP_STACK)) + if (sp < low || sp >= high) return false; - low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr); - high = low + SDEI_STACK_SIZE; + if (info) { + info->low = low; + info->high = high; + info->type = STACK_TYPE_SDEI_NORMAL; + } - if (low <= sp && sp < high) + return true; +} + +bool on_sdei_critical_stack(unsigned long sp, + struct stack_info *info) +{ + unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr); + unsigned long high = low + SDEI_STACK_SIZE; + + if (sp < low || sp >= high) + return false; + + if (info) { + info->low = low; + info->high = high; + info->type = STACK_TYPE_SDEI_CRITICAL; + } + + return true; +} + +bool _on_sdei_stack(unsigned long sp, + struct stack_info *info) +{ + if (!IS_ENABLED(CONFIG_VMAP_STACK)) + return false; + + if (on_sdei_critical_stack(sp, info)) return true; - low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr); - high = low + SDEI_STACK_SIZE; + if (on_sdei_normal_stack(sp, info)) + return true; - return (low <= sp && sp < high); + return false; } unsigned long sdei_arch_get_entry_point(int conduit) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d5718a060672..4989f7ea1e59 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -50,7 +50,7 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) if (!tsk) tsk = current; - if (!on_accessible_stack(tsk, fp)) + if (!on_accessible_stack(tsk, fp, NULL)) return -EINVAL; frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); -- cgit v1.2.3