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264c03a245
Currently the callback passed to arch_stack_walk() has an argument called reliable passed to it to indicate if the stack entry is reliable, a comment says that this is used by some printk() consumers. However in the current kernel none of the arch_stack_walk() implementations ever set this flag to true and the only callback implementation we have is in the generic stacktrace code which ignores the flag. It therefore appears that this flag is redundant so we can simplify and clarify things by removing it. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/20200914153409.25097-2-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
136 lines
3.1 KiB
C
136 lines
3.1 KiB
C
/*
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* Stack trace management functions
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*
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* Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*/
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task_stack.h>
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#include <linux/stacktrace.h>
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#include <linux/export.h>
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#include <linux/uaccess.h>
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#include <asm/stacktrace.h>
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#include <asm/unwind.h>
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void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
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struct task_struct *task, struct pt_regs *regs)
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{
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struct unwind_state state;
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unsigned long addr;
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if (regs && !consume_entry(cookie, regs->ip))
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return;
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for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
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unwind_next_frame(&state)) {
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addr = unwind_get_return_address(&state);
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if (!addr || !consume_entry(cookie, addr))
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break;
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}
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}
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/*
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* This function returns an error if it detects any unreliable features of the
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* stack. Otherwise it guarantees that the stack trace is reliable.
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*
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* If the task is not 'current', the caller *must* ensure the task is inactive.
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*/
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int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
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void *cookie, struct task_struct *task)
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{
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struct unwind_state state;
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struct pt_regs *regs;
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unsigned long addr;
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for (unwind_start(&state, task, NULL, NULL);
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!unwind_done(&state) && !unwind_error(&state);
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unwind_next_frame(&state)) {
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regs = unwind_get_entry_regs(&state, NULL);
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if (regs) {
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/* Success path for user tasks */
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if (user_mode(regs))
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return 0;
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/*
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* Kernel mode registers on the stack indicate an
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* in-kernel interrupt or exception (e.g., preemption
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* or a page fault), which can make frame pointers
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* unreliable.
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*/
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if (IS_ENABLED(CONFIG_FRAME_POINTER))
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return -EINVAL;
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}
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addr = unwind_get_return_address(&state);
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/*
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* A NULL or invalid return address probably means there's some
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* generated code which __kernel_text_address() doesn't know
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* about.
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*/
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if (!addr)
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return -EINVAL;
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if (!consume_entry(cookie, addr))
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return -EINVAL;
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}
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/* Check for stack corruption */
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if (unwind_error(&state))
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return -EINVAL;
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return 0;
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}
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/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
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struct stack_frame_user {
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const void __user *next_fp;
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unsigned long ret_addr;
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};
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static int
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copy_stack_frame(const struct stack_frame_user __user *fp,
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struct stack_frame_user *frame)
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{
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int ret;
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if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
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return 0;
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ret = 1;
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pagefault_disable();
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if (__get_user(frame->next_fp, &fp->next_fp) ||
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__get_user(frame->ret_addr, &fp->ret_addr))
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ret = 0;
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pagefault_enable();
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return ret;
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}
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void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
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const struct pt_regs *regs)
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{
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const void __user *fp = (const void __user *)regs->bp;
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if (!consume_entry(cookie, regs->ip))
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return;
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while (1) {
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struct stack_frame_user frame;
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frame.next_fp = NULL;
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frame.ret_addr = 0;
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if (!copy_stack_frame(fp, &frame))
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break;
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if ((unsigned long)fp < regs->sp)
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break;
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if (!frame.ret_addr)
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break;
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if (!consume_entry(cookie, frame.ret_addr))
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break;
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fp = frame.next_fp;
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}
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}
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