From 665ca9187c4087736fa57b0e00bcf33ea601fb6f Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Sun, 31 Jan 2016 14:23:30 +0100 Subject: s390/stacktrace: fix save_stack_trace_tsk() for current task The function save_stack_trace_tsk() did not consider that it can be used for tsk == current, for which the current stack pointer obviously cannot be found in the thread structure. Fix this and get the stack pointer with an inline assembly. This fixes e.g. the output of "cat /proc/self/stack". Before: [<0000000000000000>] (null) [] 0xffffffffffffffff After: [<000000000011b3ee>] save_stack_trace_tsk+0x56/0x98 [<0000000000366cde>] proc_pid_stack+0xae/0x108 [<00000000003636f0>] proc_single_show+0x70/0xc0 [<0000000000311fbc>] seq_read+0xcc/0x448 [<00000000002e7716>] __vfs_read+0x36/0x100 [<00000000002e872e>] vfs_read+0x76/0x130 [<00000000002e975e>] SyS_read+0x66/0xd8 [<000000000089490e>] system_call+0xd6/0x264 [] 0xffffffffffffffff Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/s390/kernel/stacktrace.c') diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 5acba3cb7220..dd484c75be56 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -86,6 +86,10 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) unsigned long sp, low, high; sp = tsk->thread.ksp; + if (tsk == current) { + /* Get current stack pointer. */ + asm volatile("la %0,0(15)" : "=a" (sp)); + } low = (unsigned long) task_stack_page(tsk); high = (unsigned long) task_pt_regs(tsk); save_context_stack(trace, sp, low, high, 0); -- cgit v1.2.3 From 9900c48c46d8bcf497972024c5fe366e6d9771f3 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 1 Feb 2016 10:13:05 +0100 Subject: s390/stacktrace: fix address ranges for asynchronous and panic stack git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets") introduced a regression in regard to save_stack_trace(). The stack pointer for the asynchronous and the panic stack in the lowcore now have an additional offset applied to them. This offset needs to be taken into account in the calculation for the low and high address for the stacks. This bug was already partially fixed with 9cc5c206d9b4 ("s390/dumpstack: fix address ranges for asynchronous and panic stack"). This patch fixes it also for the stacktrace code. Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets") Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'arch/s390/kernel/stacktrace.c') diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index dd484c75be56..225bed00aa92 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -62,17 +62,18 @@ static unsigned long save_context_stack(struct stack_trace *trace, void save_stack_trace(struct stack_trace *trace) { register unsigned long sp asm ("15"); - unsigned long orig_sp, new_sp; + unsigned long orig_sp, new_sp, frame_size; + frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); orig_sp = sp; new_sp = save_context_stack(trace, orig_sp, - S390_lowcore.panic_stack - PAGE_SIZE, - S390_lowcore.panic_stack, 1); + S390_lowcore.panic_stack + frame_size - PAGE_SIZE, + S390_lowcore.panic_stack + frame_size, 1); if (new_sp != orig_sp) return; new_sp = save_context_stack(trace, new_sp, - S390_lowcore.async_stack - ASYNC_SIZE, - S390_lowcore.async_stack, 1); + S390_lowcore.async_stack + frame_size - ASYNC_SIZE, + S390_lowcore.async_stack + frame_size, 1); if (new_sp != orig_sp) return; save_context_stack(trace, new_sp, -- cgit v1.2.3 From f6331aaccbd980a49bff1559d66abcbd46af5b0a Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 1 Feb 2016 14:06:57 +0100 Subject: s390/stacktrace: add missing end marker save_stack_trace() did not write the ULONG_MAX end marker if there is enough space left. So simply follow x86 and arm64. Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/s390/kernel/stacktrace.c') diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 225bed00aa92..75e6ea930692 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -79,6 +79,8 @@ void save_stack_trace(struct stack_trace *trace) save_context_stack(trace, new_sp, S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE, 1); + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; } EXPORT_SYMBOL_GPL(save_stack_trace); -- cgit v1.2.3 From 66adce8f1f9f3bcd743a0e72c10aa850df8c5fa7 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 1 Feb 2016 14:14:04 +0100 Subject: s390/stacktrace: save full stack traces save_stack_trace() only saves the stack trace of the current context (interrupt or process context). This is different to what other architectures like x86 do, which save the full stack trace across different contexts. Also extract a __save_stack_trace() helper function which will be used by a follow on patch. Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'arch/s390/kernel/stacktrace.c') diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 75e6ea930692..e0fec2d8ac40 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -59,26 +59,29 @@ static unsigned long save_context_stack(struct stack_trace *trace, } } -void save_stack_trace(struct stack_trace *trace) +static void __save_stack_trace(struct stack_trace *trace, unsigned long sp) { - register unsigned long sp asm ("15"); - unsigned long orig_sp, new_sp, frame_size; + unsigned long new_sp, frame_size; frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs); - orig_sp = sp; - new_sp = save_context_stack(trace, orig_sp, + new_sp = save_context_stack(trace, sp, S390_lowcore.panic_stack + frame_size - PAGE_SIZE, S390_lowcore.panic_stack + frame_size, 1); - if (new_sp != orig_sp) - return; new_sp = save_context_stack(trace, new_sp, S390_lowcore.async_stack + frame_size - ASYNC_SIZE, S390_lowcore.async_stack + frame_size, 1); - if (new_sp != orig_sp) - return; save_context_stack(trace, new_sp, S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE, 1); +} + +void save_stack_trace(struct stack_trace *trace) +{ + register unsigned long r15 asm ("15"); + unsigned long sp; + + sp = r15; + __save_stack_trace(trace, sp); if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; } -- cgit v1.2.3 From e0115875c04548255212ebd7dbd90bdbe1257f48 Mon Sep 17 00:00:00 2001 From: Pratyush Anand Date: Fri, 29 Jan 2016 10:50:28 +0530 Subject: s390/stacktrace: add save_stack_trace_regs() Implement save_stack_trace_regs, so that a stack trace of a kprobe event can be obtained. Without this we see following warning: "save_stack_trace_regs() not implemented yet." when we execute: echo stacktrace > /sys/kernel/debug/tracing/trace_options echo "p kfree" >> /sys/kernel/debug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable Reported-by: Chunyu Hu Signed-off-by: Pratyush Anand [heiko.carstens@de.ibm.com]: changed patch to use __save_stack_trace() Signed-off-by: Heiko Carstens Tested-by: Peter Oberparleiter Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/stacktrace.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'arch/s390/kernel/stacktrace.c') diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index e0fec2d8ac40..8f64ebd63767 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -103,3 +103,14 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) trace->entries[trace->nr_entries++] = ULONG_MAX; } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); + +void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) +{ + unsigned long sp; + + sp = kernel_stack_pointer(regs); + __save_stack_trace(trace, sp); + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; +} +EXPORT_SYMBOL_GPL(save_stack_trace_regs); -- cgit v1.2.3