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authorNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>2019-09-05 23:50:30 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2019-09-18 12:24:55 +1000
commit7c1bb6bbf75d8ca5ec878627d3170effcaf54f27 (patch)
treeb7c4423c0e4ed890806fa3ceecebe0458f6d79fd /arch/powerpc/kernel/process.c
parent370011a27028d6f05e598ed6211a0ca2dc0213f7 (diff)
downloadlinux-7c1bb6bbf75d8ca5ec878627d3170effcaf54f27.tar.gz
powerpc: Use ftrace_graph_ret_addr() when unwinding
With support for HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, ftrace_graph_ret_addr() provides more robust unwinding when function graph is in use. Update show_stack() to use the same. With dump_stack() added to sysrq_sysctl_handler(), before this patch: root@(none):/sys/kernel/debug/tracing# cat /proc/sys/kernel/sysrq CPU: 0 PID: 218 Comm: cat Not tainted 5.3.0-rc7-00868-g8453ad4a078c-dirty #20 Call Trace: [c0000000d1e13c30] [c00000000006ab98] return_to_handler+0x0/0x40 (dump_stack+0xe8/0x164) (unreliable) [c0000000d1e13c80] [c000000000145680] sysrq_sysctl_handler+0x48/0xb8 [c0000000d1e13cd0] [c00000000006ab98] return_to_handler+0x0/0x40 (proc_sys_call_handler+0x274/0x2a0) [c0000000d1e13d60] [c00000000006ab98] return_to_handler+0x0/0x40 (return_to_handler+0x0/0x40) [c0000000d1e13d80] [c00000000006ab98] return_to_handler+0x0/0x40 (__vfs_read+0x3c/0x70) [c0000000d1e13dd0] [c00000000006ab98] return_to_handler+0x0/0x40 (vfs_read+0xb8/0x1b0) [c0000000d1e13e20] [c00000000006ab98] return_to_handler+0x0/0x40 (ksys_read+0x7c/0x140) After this patch: Call Trace: [c0000000d1e33c30] [c00000000006ab58] return_to_handler+0x0/0x40 (dump_stack+0xe8/0x164) (unreliable) [c0000000d1e33c80] [c000000000145680] sysrq_sysctl_handler+0x48/0xb8 [c0000000d1e33cd0] [c00000000006ab58] return_to_handler+0x0/0x40 (proc_sys_call_handler+0x274/0x2a0) [c0000000d1e33d60] [c00000000006ab58] return_to_handler+0x0/0x40 (__vfs_read+0x3c/0x70) [c0000000d1e33d80] [c00000000006ab58] return_to_handler+0x0/0x40 (vfs_read+0xb8/0x1b0) [c0000000d1e33dd0] [c00000000006ab58] return_to_handler+0x0/0x40 (ksys_read+0x7c/0x140) [c0000000d1e33e20] [c00000000006ab58] return_to_handler+0x0/0x40 (system_call+0x5c/0x68) Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/dc89c9a887121342d9c7819482c3dabdece2a323.1567707399.git.naveen.n.rao@linux.vnet.ibm.com
Diffstat (limited to 'arch/powerpc/kernel/process.c')
-rw-r--r--arch/powerpc/kernel/process.c19
1 files changed, 6 insertions, 13 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 24621e7e5033..f289bdd2b562 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2047,10 +2047,8 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
int count = 0;
int firstframe = 1;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- struct ftrace_ret_stack *ret_stack;
- extern void return_to_handler(void);
- unsigned long rth = (unsigned long)return_to_handler;
- int curr_frame = 0;
+ unsigned long ret_addr;
+ int ftrace_idx = 0;
#endif
if (tsk == NULL)
@@ -2079,15 +2077,10 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
if (!firstframe || ip != lr) {
printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- if ((ip == rth) && curr_frame >= 0) {
- ret_stack = ftrace_graph_get_ret_stack(current,
- curr_frame++);
- if (ret_stack)
- pr_cont(" (%pS)",
- (void *)ret_stack->ret);
- else
- curr_frame = -1;
- }
+ ret_addr = ftrace_graph_ret_addr(current,
+ &ftrace_idx, ip, stack);
+ if (ret_addr != ip)
+ pr_cont(" (%pS)", (void *)ret_addr);
#endif
if (firstframe)
pr_cont(" (unreliable)");