blob: 7f7755cd28f077773c46be1e6b95d631f6f32cbf [file] [log] [blame]
/*
* Kernel and userspace stack tracing.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2013 Tensilica Inc.
* Copyright (C) 2015 Cadence Design Systems Inc.
*/
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <asm/stacktrace.h>
#include <asm/traps.h>
#include <linux/uaccess.h>
#if IS_ENABLED(CONFIG_PERF_EVENTS)
/* Address of common_exception_return, used to check the
* transition from kernel to user space.
*/
extern int common_exception_return;
void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth,
int (*ufn)(struct stackframe *frame, void *data),
void *data)
{
unsigned long windowstart = regs->windowstart;
unsigned long windowbase = regs->windowbase;
unsigned long a0 = regs->areg[0];
unsigned long a1 = regs->areg[1];
unsigned long pc = regs->pc;
struct stackframe frame;
int index;
if (!depth--)
return;
frame.pc = pc;
frame.sp = a1;
if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
return;
if (IS_ENABLED(CONFIG_USER_ABI_CALL0_ONLY) ||
(IS_ENABLED(CONFIG_USER_ABI_CALL0_PROBE) &&
!(regs->ps & PS_WOE_MASK)))
return;
/* Two steps:
*
* 1. Look through the register window for the
* previous PCs in the call trace.
*
* 2. Look on the stack.
*/
/* Step 1. */
/* Rotate WINDOWSTART to move the bit corresponding to
* the current window to the bit #0.
*/
windowstart = (windowstart << WSBITS | windowstart) >> windowbase;
/* Look for bits that are set, they correspond to
* valid windows.
*/
for (index = WSBITS - 1; (index > 0) && depth; depth--, index--)
if (windowstart & (1 << index)) {
/* Get the PC from a0 and a1. */
pc = MAKE_PC_FROM_RA(a0, pc);
/* Read a0 and a1 from the
* corresponding position in AREGs.
*/
a0 = regs->areg[index * 4];
a1 = regs->areg[index * 4 + 1];
frame.pc = pc;
frame.sp = a1;
if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
return;
}
/* Step 2. */
/* We are done with the register window, we need to
* look through the stack.
*/
if (!depth)
return;
/* Start from the a1 register. */
/* a1 = regs->areg[1]; */
while (a0 != 0 && depth--) {
pc = MAKE_PC_FROM_RA(a0, pc);
/* Check if the region is OK to access. */
if (!access_ok(&SPILL_SLOT(a1, 0), 8))
return;
/* Copy a1, a0 from user space stack frame. */
if (__get_user(a0, &SPILL_SLOT(a1, 0)) ||
__get_user(a1, &SPILL_SLOT(a1, 1)))
return;
frame.pc = pc;
frame.sp = a1;
if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
return;
}
}
EXPORT_SYMBOL(xtensa_backtrace_user);
void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth,
int (*kfn)(struct stackframe *frame, void *data),
int (*ufn)(struct stackframe *frame, void *data),
void *data)
{
unsigned long pc = regs->depc > VALID_DOUBLE_EXCEPTION_ADDRESS ?
regs->depc : regs->pc;
unsigned long sp_start, sp_end;
unsigned long a0 = regs->areg[0];
unsigned long a1 = regs->areg[1];
sp_start = a1 & ~(THREAD_SIZE - 1);
sp_end = sp_start + THREAD_SIZE;
/* Spill the register window to the stack first. */
spill_registers();
/* Read the stack frames one by one and create the PC
* from the a0 and a1 registers saved there.
*/
while (a1 > sp_start && a1 < sp_end && depth--) {
struct stackframe frame;
frame.pc = pc;
frame.sp = a1;
if (kernel_text_address(pc) && kfn(&frame, data))
return;
if (pc == (unsigned long)&common_exception_return) {
regs = (struct pt_regs *)a1;
if (user_mode(regs)) {
if (ufn == NULL)
return;
xtensa_backtrace_user(regs, depth, ufn, data);
return;
}
a0 = regs->areg[0];
a1 = regs->areg[1];
continue;
}
sp_start = a1;
pc = MAKE_PC_FROM_RA(a0, pc);
a0 = SPILL_SLOT(a1, 0);
a1 = SPILL_SLOT(a1, 1);
}
}
EXPORT_SYMBOL(xtensa_backtrace_kernel);
#endif
void walk_stackframe(unsigned long *sp,
int (*fn)(struct stackframe *frame, void *data),
void *data)
{
unsigned long a0, a1;
unsigned long sp_end;
a1 = (unsigned long)sp;
sp_end = ALIGN(a1, THREAD_SIZE);
spill_registers();
while (a1 < sp_end) {
struct stackframe frame;
sp = (unsigned long *)a1;
a0 = SPILL_SLOT(a1, 0);
a1 = SPILL_SLOT(a1, 1);
if (a1 <= (unsigned long)sp)
break;
frame.pc = MAKE_PC_FROM_RA(a0, a1);
frame.sp = a1;
if (fn(&frame, data))
return;
}
}
#ifdef CONFIG_STACKTRACE
struct stack_trace_data {
struct stack_trace *trace;
unsigned skip;
};
static int stack_trace_cb(struct stackframe *frame, void *data)
{
struct stack_trace_data *trace_data = data;
struct stack_trace *trace = trace_data->trace;
if (trace_data->skip) {
--trace_data->skip;
return 0;
}
if (!kernel_text_address(frame->pc))
return 0;
trace->entries[trace->nr_entries++] = frame->pc;
return trace->nr_entries >= trace->max_entries;
}
void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
{
struct stack_trace_data trace_data = {
.trace = trace,
.skip = trace->skip,
};
walk_stackframe(stack_pointer(task), stack_trace_cb, &trace_data);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
void save_stack_trace(struct stack_trace *trace)
{
save_stack_trace_tsk(current, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace);
#endif
#ifdef CONFIG_FRAME_POINTER
struct return_addr_data {
unsigned long addr;
unsigned skip;
};
static int return_address_cb(struct stackframe *frame, void *data)
{
struct return_addr_data *r = data;
if (r->skip) {
--r->skip;
return 0;
}
if (!kernel_text_address(frame->pc))
return 0;
r->addr = frame->pc;
return 1;
}
/*
* level == 0 is for the return address from the caller of this function,
* not from this function itself.
*/
unsigned long return_address(unsigned level)
{
struct return_addr_data r = {
.skip = level,
};
walk_stackframe(stack_pointer(NULL), return_address_cb, &r);
return r.addr;
}
EXPORT_SYMBOL(return_address);
#endif