zephyr/subsys/profiling/perf/backends/perf_x86.c

95 lines
2.1 KiB
C

/*
* Copyright (c) 2023 KNS Group LLC (YADRO)
* Copyright (c) 2020 Yonatan Goldschmidt <yon.goldschmidt@gmail.com>
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
static bool valid_stack(uintptr_t addr, k_tid_t current)
{
return current->stack_info.start <= addr &&
addr < current->stack_info.start + current->stack_info.size;
}
static inline bool in_text_region(uintptr_t addr)
{
extern uintptr_t __text_region_start, __text_region_end;
return (addr >= (uintptr_t)&__text_region_start) && (addr < (uintptr_t)&__text_region_end);
}
/* interruption stack frame */
struct isf {
uint32_t ebp;
uint32_t ecx;
uint32_t edx;
uint32_t eax;
uint32_t eip;
};
/*
* This function use frame pointers to unwind stack and get trace of return addresses.
* Return addresses are translated in corresponding function's names using .elf file.
* So we get function call trace
*/
size_t arch_perf_current_stack_trace(uintptr_t *buf, size_t size)
{
if (size < 1U) {
return 0;
}
size_t idx = 0;
const struct isf * const isf =
*((struct isf **)(((void **)_current_cpu->irq_stack)-1));
/*
* In x86 (arch/x86/core/ia32/intstub.S) %eip and %ebp
* are saved at the beginning of _interrupt_enter in order, that described
* in struct esf. Core switch %esp to
* _current_cpu->irq_stack and push %esp on irq stack
*
* The following lines lines do the reverse things to get %eip and %ebp
* from thread stack
*/
void **fp = (void **)isf->ebp;
/*
* %ebp is frame pointer.
*
* stack frame in memory:
* (addresses growth up)
* ....
* ra
* %ebp (next) <- %ebp (curr)
* ....
*/
buf[idx++] = (uintptr_t)isf->eip;
while (valid_stack((uintptr_t)fp, _current)) {
if (idx >= size) {
return 0;
}
if (!in_text_region((uintptr_t)fp[1])) {
break;
}
buf[idx++] = (uintptr_t)fp[1];
void **new_fp = (void **)fp[0];
/*
* anti-infinity-loop if
* new_fp can't be smaller than fp, cause the stack is growing down
* and trace moves deeper into the stack
*/
if (new_fp <= fp) {
break;
}
fp = new_fp;
}
return idx;
}