trace.c

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#include <core/system.h>
#include <core/printk.h>
#include <boot/boot.h>

struct stack_frame {
    struct stack_frame *bp;
    uintptr_t ip;
};
 
extern struct boot *__kboot;
 
int __printing_trace = 0;

static const elf_sym_t *symbol_of(uintptr_t ip)
{
    if (!__kboot || !__kboot->symtab || !__kboot->strtab)
        return NULL;
 
    const elf_sym_t *sym = (const elf_sym_t *) (uintptr_t) __kboot->symtab->sh_addr;
 
    for (size_t i = 0; i < __kboot->symnum; ++i, ++sym)
        if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
            ip >= sym->st_value && ip < sym->st_value + sym->st_size)
            return sym;
 
    return NULL;
}
 
/* Prints the stack trace of the running code, up to 20 frames. */
void arch_stack_trace(void)
{
    __printing_trace = 1;
 
    struct stack_frame *stk = NULL;
 
#if ARCH_BITS==32
    asm volatile ("movl %%ebp, %0":"=r"(stk));
#else
    asm volatile ("movq %%rbp, %0":"=r"(stk));
#endif
 
    printk("stack trace:\n");
 
    for (int frame = 0; stk && frame < 20; ++frame) {
        const elf_sym_t *sym = symbol_of(stk->ip);
 
        if (sym) {
            const char *names = (const char *) (uintptr_t) __kboot->strtab->sh_addr;
            printk("  [%p] %s+0x%lx\n", stk->ip, names + sym->st_name, (unsigned long) (stk->ip - sym->st_value));
        } else {
            printk("  [%p]\n", stk->ip);
        }
 
        stk = stk->bp;
    }
}