1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Performance counter callchain support - powerpc architecture code 4 * 5 * Copyright © 2009 Paul Mackerras, IBM Corporation. 6 */ 7 #include <linux/kernel.h> 8 #include <linux/sched.h> 9 #include <linux/perf_event.h> 10 #include <linux/percpu.h> 11 #include <linux/uaccess.h> 12 #include <linux/mm.h> 13 #include <asm/ptrace.h> 14 #include <asm/sigcontext.h> 15 #include <asm/ucontext.h> 16 #include <asm/vdso.h> 17 #include <asm/pte-walk.h> 18 19 #include "callchain.h" 20 21 /* 22 * Is sp valid as the address of the next kernel stack frame after prev_sp? 23 * The next frame may be in a different stack area but should not go 24 * back down in the same stack area. 25 */ 26 static int valid_next_sp(unsigned long sp, unsigned long prev_sp) 27 { 28 if (sp & 0xf) 29 return 0; /* must be 16-byte aligned */ 30 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) 31 return 0; 32 if (sp >= prev_sp + STACK_FRAME_MIN_SIZE) 33 return 1; 34 /* 35 * sp could decrease when we jump off an interrupt stack 36 * back to the regular process stack. 37 */ 38 if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1))) 39 return 1; 40 return 0; 41 } 42 43 void 44 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) 45 { 46 unsigned long sp, next_sp; 47 unsigned long next_ip; 48 unsigned long lr; 49 long level = 0; 50 unsigned long *fp; 51 52 lr = regs->link; 53 sp = regs->gpr[1]; 54 perf_callchain_store(entry, perf_instruction_pointer(regs)); 55 56 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) 57 return; 58 59 for (;;) { 60 fp = (unsigned long *) sp; 61 next_sp = fp[0]; 62 63 if (next_sp == sp + STACK_INT_FRAME_SIZE && 64 fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) { 65 /* 66 * This looks like an interrupt frame for an 67 * interrupt that occurred in the kernel 68 */ 69 regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD); 70 next_ip = regs->nip; 71 lr = regs->link; 72 level = 0; 73 perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL); 74 75 } else { 76 if (level == 0) 77 next_ip = lr; 78 else 79 next_ip = fp[STACK_FRAME_LR_SAVE]; 80 81 /* 82 * We can't tell which of the first two addresses 83 * we get are valid, but we can filter out the 84 * obviously bogus ones here. We replace them 85 * with 0 rather than removing them entirely so 86 * that userspace can tell which is which. 87 */ 88 if ((level == 1 && next_ip == lr) || 89 (level <= 1 && !kernel_text_address(next_ip))) 90 next_ip = 0; 91 92 ++level; 93 } 94 95 perf_callchain_store(entry, next_ip); 96 if (!valid_next_sp(next_sp, sp)) 97 return; 98 sp = next_sp; 99 } 100 } 101 102 void 103 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) 104 { 105 if (!is_32bit_task()) 106 perf_callchain_user_64(entry, regs); 107 else 108 perf_callchain_user_32(entry, regs); 109 } 110