e1e95b2887
Replace the dynamic allocation in os_backtrace_symbols() with a static buffer embedded in struct backtrace_ctx. This avoids malloc recursion when backtrace is called from within dlmalloc (e.g., for the upcoming mcheck caller-tracking). The API gets a complete rework as part of this: - Combine addrs[] and syms[] arrays into struct backtrace_frame with addr and sym fields - Store the strings in a unified buffer, with pointers from an array - Change os_backtrace_symbols() to take ctx pointer and fill sym_buf - Remove os_backtrace_symbols_free() as nothing needs freeing - Rename BACKTRACE_MAX to BACKTRACE_MAX_FRAMES Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com>
120 lines
2.5 KiB
C
120 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* OS-level backtrace support for sandbox
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*
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* Copyright 2025 Canonical Ltd
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* Written by Simon Glass <simon.glass@canonical.com>
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*/
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#define _GNU_SOURCE
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#include <backtrace.h>
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#include <execinfo.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <os.h>
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/* For BACKTRACE_MAX_FRAMES - include U-Boot's header after system headers */
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#include "../../../include/backtrace.h"
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/* libbacktrace state - created once and cached */
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static struct backtrace_state *bt_state;
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/* Context for collecting symbol info */
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struct bt_sym_ctx {
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char *buf;
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size_t size;
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int found;
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};
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uint os_backtrace(void **buffer, uint size, uint skip)
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{
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void *tmp[size + skip];
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uint count;
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int nptrs;
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nptrs = backtrace(tmp, size + skip);
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if ((int)skip >= nptrs)
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return 0;
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count = nptrs - skip;
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memcpy(buffer, tmp + skip, count * sizeof(*buffer));
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return count;
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}
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static void bt_error_callback(void *data, const char *msg, int errnum)
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{
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/* Silently ignore errors - we'll fall back to addresses */
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}
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static struct backtrace_state *get_bt_state(void)
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{
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if (!bt_state)
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bt_state = backtrace_create_state(NULL, 0, bt_error_callback,
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NULL);
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return bt_state;
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}
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static int bt_full_callback(void *data, uintptr_t pc, const char *fname,
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int lineno, const char *func)
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{
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struct bt_sym_ctx *ctx = data;
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if (func) {
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if (fname && lineno)
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snprintf(ctx->buf, ctx->size, "%s() at %s:%d", func,
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fname, lineno);
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else if (fname)
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snprintf(ctx->buf, ctx->size, "%s() at %s", func,
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fname);
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else
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snprintf(ctx->buf, ctx->size, "%s()", func);
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ctx->found = 1;
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}
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return 0; /* continue to get innermost frame for inlined functions */
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}
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void os_backtrace_symbols(struct backtrace_ctx *ctx)
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{
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char *end = ctx->sym_buf + BACKTRACE_SYM_BUFSZ;
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struct backtrace_state *state;
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char *p = ctx->sym_buf;
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int remaining, i;
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state = get_bt_state();
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for (i = 0; i < ctx->count; i++) {
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struct backtrace_frame *frame = &ctx->frame[i];
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struct bt_sym_ctx sym_ctx;
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remaining = end - p;
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if (remaining <= 1) {
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/* No more space, leave remaining syms as NULL */
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frame->sym = NULL;
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continue;
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}
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frame->sym = p;
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sym_ctx.buf = p;
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sym_ctx.size = remaining;
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sym_ctx.found = 0;
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if (state) {
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backtrace_pcinfo(state, (uintptr_t)frame->addr,
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bt_full_callback, bt_error_callback,
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&sym_ctx);
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}
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/* Fall back to address if no symbol found */
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if (!sym_ctx.found)
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snprintf(p, remaining, "%p", frame->addr);
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p += strlen(p) + 1;
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}
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}
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