| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Perf callchain handling code. |
| * |
| * Based on the ARM perf implementation. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/sched.h> |
| #include <linux/perf_event.h> |
| #include <linux/uaccess.h> |
| #include <asm/ptrace.h> |
| #include <asm/stacktrace.h> |
| |
| static bool is_valid_call(unsigned long calladdr) |
| { |
| unsigned int callinsn; |
| |
| /* Check the possible return address is aligned. */ |
| if (!(calladdr & 0x3)) { |
| if (!get_user(callinsn, (unsigned int *)calladdr)) { |
| /* Check for CALLR or SWAP PC,D1RtP. */ |
| if ((callinsn & 0xff000000) == 0xab000000 || |
| callinsn == 0xa3200aa0) |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| static struct metag_frame __user * |
| user_backtrace(struct metag_frame __user *user_frame, |
| struct perf_callchain_entry_ctx *entry) |
| { |
| struct metag_frame frame; |
| unsigned long calladdr; |
| |
| /* We cannot rely on having frame pointers in user code. */ |
| while (1) { |
| /* Also check accessibility of one struct frame beyond */ |
| if (!access_ok(VERIFY_READ, user_frame, sizeof(frame))) |
| return 0; |
| if (__copy_from_user_inatomic(&frame, user_frame, |
| sizeof(frame))) |
| return 0; |
| |
| --user_frame; |
| |
| calladdr = frame.lr - 4; |
| if (is_valid_call(calladdr)) { |
| perf_callchain_store(entry, calladdr); |
| return user_frame; |
| } |
| } |
| |
| return 0; |
| } |
| |
| void |
| perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) |
| { |
| unsigned long sp = regs->ctx.AX[0].U0; |
| struct metag_frame __user *frame; |
| |
| frame = (struct metag_frame __user *)sp; |
| |
| --frame; |
| |
| while ((entry->nr < entry->max_stack) && frame) |
| frame = user_backtrace(frame, 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; |
| |
| fr.fp = regs->ctx.AX[1].U0; |
| fr.sp = regs->ctx.AX[0].U0; |
| fr.lr = regs->ctx.DX[4].U1; |
| fr.pc = regs->ctx.CurrPC; |
| walk_stackframe(&fr, callchain_trace, entry); |
| } |