// SPDX-License-Identifier: GPL-2.0 /* * ARM callchain support * * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com> * * This code is based on the ARM OProfile backtrace code. */ #include <linux/perf_event.h> #include <linux/uaccess.h> #include <asm/stacktrace.h> /* * The registers we're interested in are at the end of the variable * length saved register structure. The fp points at the end of this * structure so the address of this struct is: * (struct frame_tail *)(xxx->fp)-1 * * This code has been adapted from the ARM OProfile support. */ struct frame_tail { struct frame_tail __user *fp; unsigned long sp; unsigned long lr; } __attribute__((packed)); /* * Get the return address for a single stackframe and return a pointer to the * next frame tail. */ static struct frame_tail __user * user_backtrace(struct frame_tail __user *tail, struct perf_callchain_entry_ctx *entry) { struct frame_tail buftail; unsigned long err; if (!access_ok(tail, sizeof(buftail))) return NULL; pagefault_disable(); err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); pagefault_enable(); if (err) return NULL; perf_callchain_store(entry, buftail.lr); /* * Frame pointers should strictly progress back up the stack * (towards higher addresses). */ if (tail + 1 >= buftail.fp) return NULL; return buftail.fp - 1; } void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { struct frame_tail __user *tail; perf_callchain_store(entry, regs->ARM_pc); if (!current->mm) return; tail = (struct frame_tail __user *)regs->ARM_fp - 1; while ((entry->nr < entry->max_stack) && tail && !((unsigned long)tail & 0x3)) tail = user_backtrace(tail, entry); } /* * Gets called by walk_stackframe() for every stackframe. This will be called * whist unwinding the stackframe and is like a subroutine return so we use * the PC. */ static int callchain_trace(struct stackframe *fr, void *data) { struct perf_callchain_entry_ctx *entry = data; perf_callchain_store(entry, fr->pc); return 0; } void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { struct stackframe fr; arm_get_current_stackframe(regs, &fr); walk_stackframe(&fr, callchain_trace, entry); } unsigned long perf_instruction_pointer(struct pt_regs *regs) { return instruction_pointer(regs); } unsigned long perf_misc_flags(struct pt_regs *regs) { int misc = 0; if (user_mode(regs)) misc |= PERF_RECORD_MISC_USER; else misc |= PERF_RECORD_MISC_KERNEL; return misc; }