![Dave Martin](/assets/img/avatar_default.png)
Some common code is required by each stacktrace user to initialise struct stackframe before the first call to unwind_frame(). In preparation for adding to the common code, this patch factors it out into a separate function start_backtrace(), and modifies the stacktrace callers appropriately. No functional change. Signed-off-by: Dave Martin <dave.martin@arm.com> [Mark: drop tsk argument, update more callsites] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: James Morse <james.morse@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
187 lines
4.4 KiB
C
187 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* arm64 callchain support
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*
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* Copyright (C) 2015 ARM Limited
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*/
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#include <linux/perf_event.h>
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#include <linux/uaccess.h>
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#include <asm/pointer_auth.h>
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#include <asm/stacktrace.h>
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struct frame_tail {
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struct frame_tail __user *fp;
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unsigned long lr;
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} __attribute__((packed));
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/*
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* Get the return address for a single stackframe and return a pointer to the
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* next frame tail.
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*/
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static struct frame_tail __user *
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user_backtrace(struct frame_tail __user *tail,
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struct perf_callchain_entry_ctx *entry)
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{
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struct frame_tail buftail;
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unsigned long err;
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unsigned long lr;
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/* Also check accessibility of one struct frame_tail beyond */
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if (!access_ok(tail, sizeof(buftail)))
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return NULL;
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pagefault_disable();
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err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
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pagefault_enable();
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if (err)
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return NULL;
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lr = ptrauth_strip_insn_pac(buftail.lr);
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perf_callchain_store(entry, lr);
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/*
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* Frame pointers should strictly progress back up the stack
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* (towards higher addresses).
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*/
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if (tail >= buftail.fp)
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return NULL;
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return buftail.fp;
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}
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#ifdef CONFIG_COMPAT
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/*
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* The registers we're interested in are at the end of the variable
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* length saved register structure. The fp points at the end of this
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* structure so the address of this struct is:
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* (struct compat_frame_tail *)(xxx->fp)-1
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*
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* This code has been adapted from the ARM OProfile support.
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*/
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struct compat_frame_tail {
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compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */
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u32 sp;
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u32 lr;
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} __attribute__((packed));
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static struct compat_frame_tail __user *
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compat_user_backtrace(struct compat_frame_tail __user *tail,
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struct perf_callchain_entry_ctx *entry)
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{
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struct compat_frame_tail buftail;
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unsigned long err;
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/* Also check accessibility of one struct frame_tail beyond */
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if (!access_ok(tail, sizeof(buftail)))
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return NULL;
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pagefault_disable();
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err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
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pagefault_enable();
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if (err)
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return NULL;
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perf_callchain_store(entry, buftail.lr);
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/*
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* Frame pointers should strictly progress back up the stack
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* (towards higher addresses).
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*/
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if (tail + 1 >= (struct compat_frame_tail __user *)
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compat_ptr(buftail.fp))
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return NULL;
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return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
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}
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#endif /* CONFIG_COMPAT */
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void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
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/* We don't support guest os callchain now */
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return;
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}
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perf_callchain_store(entry, regs->pc);
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if (!compat_user_mode(regs)) {
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/* AARCH64 mode */
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struct frame_tail __user *tail;
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tail = (struct frame_tail __user *)regs->regs[29];
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while (entry->nr < entry->max_stack &&
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tail && !((unsigned long)tail & 0xf))
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tail = user_backtrace(tail, entry);
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} else {
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#ifdef CONFIG_COMPAT
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/* AARCH32 compat mode */
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struct compat_frame_tail __user *tail;
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tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;
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while ((entry->nr < entry->max_stack) &&
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tail && !((unsigned long)tail & 0x3))
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tail = compat_user_backtrace(tail, entry);
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#endif
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}
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}
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/*
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* Gets called by walk_stackframe() for every stackframe. This will be called
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* whist unwinding the stackframe and is like a subroutine return so we use
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* the PC.
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*/
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static int callchain_trace(struct stackframe *frame, void *data)
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{
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struct perf_callchain_entry_ctx *entry = data;
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perf_callchain_store(entry, frame->pc);
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return 0;
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}
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void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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struct stackframe frame;
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
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/* We don't support guest os callchain now */
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return;
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}
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start_backtrace(&frame, regs->regs[29], regs->pc);
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walk_stackframe(current, &frame, callchain_trace, entry);
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}
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unsigned long perf_instruction_pointer(struct pt_regs *regs)
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{
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
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return perf_guest_cbs->get_guest_ip();
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return instruction_pointer(regs);
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}
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unsigned long perf_misc_flags(struct pt_regs *regs)
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{
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int misc = 0;
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
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if (perf_guest_cbs->is_user_mode())
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misc |= PERF_RECORD_MISC_GUEST_USER;
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else
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misc |= PERF_RECORD_MISC_GUEST_KERNEL;
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} else {
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if (user_mode(regs))
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misc |= PERF_RECORD_MISC_USER;
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else
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misc |= PERF_RECORD_MISC_KERNEL;
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}
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return misc;
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}
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