From cb76c93982404273d746f3ccd5085b47689099a8 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 14 Sep 2016 21:07:42 -0500 Subject: x86/dumpstack: Add get_stack_info() interface valid_stack_ptr() is buggy: it assumes that all stacks are of size THREAD_SIZE, which is not true for exception stacks. So the walk_stack() callbacks will need to know the location of the beginning of the stack as well as the end. Another issue is that in general the various features of a stack (type, size, next stack pointer, description string) are scattered around in various places throughout the stack dump code. Encapsulate all that information in a single place with a new stack_info struct and a get_stack_info() interface. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Byungchul Park Cc: Denys Vlasenko Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Nilay Vaish Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/8164dd0db96b7e6a279fa17ae5e6dc375eecb4a9.1473905218.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel/stacktrace.c') diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 4738f5e0f2ab..785aef1c7ef5 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -9,7 +9,7 @@ #include #include -static int save_stack_stack(void *data, char *name) +static int save_stack_stack(void *data, const char *name) { return 0; } -- cgit v1.2.3 From 1959a60182f48879635812a03a99c02231ea8677 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 15 Sep 2016 22:45:45 -0700 Subject: x86/dumpstack: Pin the target stack when dumping it Specifically, pin the stack in save_stack_trace_tsk() and show_trace_log_lvl(). This will prevent a crash if the target task dies before or while dumping its stack once we start freeing task stacks early. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/cf0082cde65d1941a996d026f2b2cdbfaca17bfa.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack_32.c | 5 +++++ arch/x86/kernel/dumpstack_64.c | 5 +++++ arch/x86/kernel/stacktrace.c | 5 +++++ 3 files changed, 15 insertions(+) (limited to 'arch/x86/kernel/stacktrace.c') diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c index 2d65cfa5e0b4..122f37d7bb7e 100644 --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -163,6 +163,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *stack; int i; + if (!try_get_task_stack(task)) + return; + sp = sp ? : get_stack_pointer(task, regs); stack = sp; @@ -179,6 +182,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, } pr_cont("\n"); show_trace_log_lvl(task, regs, sp, bp, log_lvl); + + put_task_stack(task); } diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 8cb6004a4dfd..16c0d5f89b5e 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -218,6 +218,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *stack; int i; + if (!try_get_task_stack(task)) + return; + irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr); irq_stack = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long)); @@ -253,6 +256,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, pr_cont("\n"); show_trace_log_lvl(task, regs, sp, bp, log_lvl); + + put_task_stack(task); } void show_regs(struct pt_regs *regs) diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 785aef1c7ef5..23fa81e24c8a 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -79,9 +79,14 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { + if (!try_get_task_stack(tsk)) + return; + dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace); if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; + + put_task_stack(tsk); } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); -- cgit v1.2.3 From 49a612c6b06defbd6e6d334c683fea28006728e3 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Fri, 16 Sep 2016 14:18:14 -0500 Subject: x86/stacktrace: Convert save_stack_trace_*() to use the new unwinder Convert save_stack_trace_*() to use the new unwinder. dump_trace() has been deprecated. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Byungchul Park Cc: Denys Vlasenko Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Nilay Vaish Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/815494c627d89887db0ce56ceffd58ad16ee6c21.1474045023.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/stacktrace.c | 74 +++++++++++++++++--------------------------- 1 file changed, 29 insertions(+), 45 deletions(-) (limited to 'arch/x86/kernel/stacktrace.c') diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 23fa81e24c8a..0653788026e2 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -8,73 +8,59 @@ #include #include #include +#include -static int save_stack_stack(void *data, const char *name) +static int save_stack_address(struct stack_trace *trace, unsigned long addr, + bool nosched) { - return 0; -} - -static int -__save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched) -{ - struct stack_trace *trace = data; -#ifdef CONFIG_FRAME_POINTER - if (!reliable) - return 0; -#endif if (nosched && in_sched_functions(addr)) return 0; + if (trace->skip > 0) { trace->skip--; return 0; } - if (trace->nr_entries < trace->max_entries) { - trace->entries[trace->nr_entries++] = addr; - return 0; - } else { - return -1; /* no more room, stop walking the stack */ - } -} -static int save_stack_address(void *data, unsigned long addr, int reliable) -{ - return __save_stack_address(data, addr, reliable, false); + if (trace->nr_entries >= trace->max_entries) + return -1; + + trace->entries[trace->nr_entries++] = addr; + return 0; } -static int -save_stack_address_nosched(void *data, unsigned long addr, int reliable) +static void __save_stack_trace(struct stack_trace *trace, + struct task_struct *task, struct pt_regs *regs, + bool nosched) { - return __save_stack_address(data, addr, reliable, true); -} + struct unwind_state state; + unsigned long addr; -static const struct stacktrace_ops save_stack_ops = { - .stack = save_stack_stack, - .address = save_stack_address, - .walk_stack = print_context_stack, -}; + if (regs) + save_stack_address(trace, regs->ip, nosched); -static const struct stacktrace_ops save_stack_ops_nosched = { - .stack = save_stack_stack, - .address = save_stack_address_nosched, - .walk_stack = print_context_stack, -}; + for (unwind_start(&state, task, regs, NULL); !unwind_done(&state); + unwind_next_frame(&state)) { + addr = unwind_get_return_address(&state); + if (!addr || save_stack_address(trace, addr, nosched)) + break; + } + + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; +} /* * Save stack-backtrace addresses into a stack_trace buffer. */ void save_stack_trace(struct stack_trace *trace) { - dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace); - if (trace->nr_entries < trace->max_entries) - trace->entries[trace->nr_entries++] = ULONG_MAX; + __save_stack_trace(trace, current, NULL, false); } EXPORT_SYMBOL_GPL(save_stack_trace); void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) { - dump_trace(current, regs, NULL, 0, &save_stack_ops, trace); - if (trace->nr_entries < trace->max_entries) - trace->entries[trace->nr_entries++] = ULONG_MAX; + __save_stack_trace(trace, current, regs, false); } void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) @@ -82,9 +68,7 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) if (!try_get_task_stack(tsk)) return; - dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace); - if (trace->nr_entries < trace->max_entries) - trace->entries[trace->nr_entries++] = ULONG_MAX; + __save_stack_trace(trace, tsk, NULL, true); put_task_stack(tsk); } -- cgit v1.2.3