538b9265c0
The ftrace graph tracer needs to override the return address of an instrumented function, in order to install a hook that gets invoked when the function returns again. Currently, we only support this when building for ARM using GCC with frame pointers, as in this case, it is guaranteed that the function will reload LR from [FP, #-4] in all cases, and we can simply pass that address to the ftrace code. In order to support this for configurations that rely on the EABI unwinder, such as Thumb2 builds, make the unwinder keep track of the address from which LR was unwound, permitting ftrace to make use of this in a subsequent patch. Drop the call to is_kernel_text_address(), which is problematic in terms of ftrace recursion, given that it may be instrumented itself. The call is redundant anyway, as no unwind directives will be found unless the PC points to memory that is known to contain executable code. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_STACKTRACE_H
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#define __ASM_STACKTRACE_H
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#include <asm/ptrace.h>
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#include <linux/llist.h>
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struct stackframe {
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/*
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* FP member should hold R7 when CONFIG_THUMB2_KERNEL is enabled
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* and R11 otherwise.
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*/
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unsigned long fp;
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unsigned long sp;
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unsigned long lr;
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unsigned long pc;
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/* address of the LR value on the stack */
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unsigned long *lr_addr;
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#ifdef CONFIG_KRETPROBES
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struct llist_node *kr_cur;
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struct task_struct *tsk;
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#endif
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#ifdef CONFIG_ARM_UNWIND
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/*
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* This field is used to track the stack pointer value when calling
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* __entry routines. This is needed when IRQ stacks and overflow stacks
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* are used, because in that case, the struct pt_regs passed to these
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* __entry routines may be at the top of the task stack, while we are
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* executing from another stack.
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*/
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unsigned long sp_low;
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#endif
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};
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static __always_inline
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void arm_get_current_stackframe(struct pt_regs *regs, struct stackframe *frame)
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{
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frame->fp = frame_pointer(regs);
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frame->sp = regs->ARM_sp;
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frame->lr = regs->ARM_lr;
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frame->pc = regs->ARM_pc;
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#ifdef CONFIG_KRETPROBES
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frame->kr_cur = NULL;
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frame->tsk = current;
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#endif
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}
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extern int unwind_frame(struct stackframe *frame);
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extern void walk_stackframe(struct stackframe *frame,
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int (*fn)(struct stackframe *, void *), void *data);
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extern void dump_mem(const char *lvl, const char *str, unsigned long bottom,
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unsigned long top);
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#endif /* __ASM_STACKTRACE_H */
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