0cf38dc8c8
Add a new function backtrace_str() that returns a condensed backtrace string containing function names and line numbers separated by " <-". For example: "func_a:123 <-func_b:456 <-func_c:789" This is useful for logging and debugging where a compact representation of the call stack is needed. The depth is controlled by the new CONFIG_BACKTRACE_DEPTH option (default 3). Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com>
134 lines
4.0 KiB
C
134 lines
4.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Backtrace support
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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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#ifndef __BACKTRACE_H
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#define __BACKTRACE_H
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/* Maximum number of stack frames that can be collected */
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#define BACKTRACE_MAX_FRAMES 100
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/* Size of buffer for all symbol strings combined */
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#define BACKTRACE_SYM_BUFSZ (4 * 1024)
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/**
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* struct backtrace_frame - a single stack frame in a backtrace
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*
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* @addr: return address for this frame
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* @sym: pointer to symbol string in backtrace_ctx->sym_buf, or NULL if not
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* yet resolved or if sym_buf ran out of space
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*/
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struct backtrace_frame {
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void *addr;
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char *sym;
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};
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/**
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* struct backtrace_ctx - context for backtrace operations
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*
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* This structure holds all state for collecting and symbolising a backtrace.
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* It should be declared static to avoid consuming stack space (~5KB).
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*
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* Lifecycle:
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* 1. Call backtrace_init() - fills @frame[].addr with return addresses and
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* sets @count. The @frame[].sym pointers are initialised to NULL.
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* 2. Call backtrace_get_syms() - resolves addresses to symbol strings,
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* writing them into @sym_buf and setting @frame[].sym pointers.
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* 3. Access @frame[0..count-1] to read addresses and symbol strings.
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* 4. Call backtrace_uninit() to release resources (currently a no-op).
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*
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* @frame: array of stack frames
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* @count: number of valid entries in @frame
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* @sym_buf: buffer holding NUL-terminated symbol strings packed consecutively
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*/
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struct backtrace_ctx {
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struct backtrace_frame frame[BACKTRACE_MAX_FRAMES];
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unsigned int count;
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char sym_buf[BACKTRACE_SYM_BUFSZ];
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};
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/**
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* backtrace_init() - collect a backtrace
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*
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* Collect backtrace addresses into the context. Call backtrace_uninit() when
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* done with the context.
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*
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* @ctx: context to fill
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* @skip: number of stack frames to skip (0 to include backtrace_init itself)
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* Return: number of addresses collected, or -ve on error (e.g. -ENOSYS)
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*/
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int backtrace_init(struct backtrace_ctx *ctx, unsigned int skip);
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/**
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* backtrace_get_syms() - get symbol strings for a backtrace
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*
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* Convert the addresses in the context to symbol strings. The strings are
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* stored in ctx->syms[]. The caller must provide a buffer of sufficient size.
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*
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* @ctx: context with addresses from backtrace_init()
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* @buf: buffer to use for string storage
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* @size: size of buffer in bytes
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* Return: 0 if OK, -ENOSPC if buffer too small
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*/
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int backtrace_get_syms(struct backtrace_ctx *ctx, char *buf, int size);
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/**
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* backtrace_uninit() - free backtrace resources
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*
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* Free any memory allocated in the context.
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*
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* @ctx: context to free
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*/
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void backtrace_uninit(struct backtrace_ctx *ctx);
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/**
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* backtrace_show() - print a backtrace
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*
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* Print a backtrace of the current call stack.
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*
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* Return: 0 if OK, -ve on error
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*/
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int backtrace_show(void);
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/**
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* backtrace_strf() - get a condensed backtrace string into a buffer
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*
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* Return a string containing the last CONFIG_BACKTRACE_SUMMARY_FRAMES function names
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* and line number, separated by ``<-``.
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*
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* For example: ``func_a:12 <-func_b:34 <-func_c:56``
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*
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* @skip: number of stack frames to skip (0 to include backtrace_strf itself)
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* @buf: buffer to write the string to
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* @size: size of buffer
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* Return: pointer to buf, or NULL on error
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*/
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char *backtrace_strf(unsigned int skip, char *buf, int size);
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/**
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* backtrace_str() - get a condensed backtrace string
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*
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* Return a string containing the last CONFIG_BACKTRACE_SUMMARY_FRAMES function names
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* and line number, separated by ``<-``. The string is statically allocated and
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* will be overwritten on the next call.
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*
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* For example: ``func_a:12 <-func_b:34 <-func_c:56``
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*
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* @skip: number of stack frames to skip (0 to include backtrace_str itself)
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* Return: pointer to static string, or NULL on error
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*/
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#if CONFIG_IS_ENABLED(BACKTRACE)
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const char *backtrace_str(unsigned int skip);
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#else
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static inline const char *backtrace_str(unsigned int skip)
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{
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return NULL;
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}
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#endif
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#endif /* __BACKTRACE_H */
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