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 static int read_user_stack_64(const unsigned long __user *ptr, unsigned long *ret) 22 { 23 return __read_user_stack(ptr, ret, sizeof(*ret)); 24 } 25 26 /* 27 * 64-bit user processes use the same stack frame for RT and non-RT signals. 28 */ 29 struct signal_frame_64 { 30 char dummy[__SIGNAL_FRAMESIZE]; 31 struct ucontext uc; 32 unsigned long unused[2]; 33 unsigned int tramp[6]; 34 struct siginfo *pinfo; 35 void *puc; 36 struct siginfo info; 37 char abigap[288]; 38 }; 39 40 static int is_sigreturn_64_address(unsigned long nip, unsigned long fp) 41 { 42 if (nip == fp + offsetof(struct signal_frame_64, tramp)) 43 return 1; 44 if (current->mm->context.vdso && 45 nip == VDSO64_SYMBOL(current->mm->context.vdso, sigtramp_rt64)) 46 return 1; 47 return 0; 48 } 49 50 /* 51 * Do some sanity checking on the signal frame pointed to by sp. 52 * We check the pinfo and puc pointers in the frame. 53 */ 54 static int sane_signal_64_frame(unsigned long sp) 55 { 56 struct signal_frame_64 __user *sf; 57 unsigned long pinfo, puc; 58 59 sf = (struct signal_frame_64 __user *) sp; 60 if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) || 61 read_user_stack_64((unsigned long __user *) &sf->puc, &puc)) 62 return 0; 63 return pinfo == (unsigned long) &sf->info && 64 puc == (unsigned long) &sf->uc; 65 } 66 67 void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, 68 struct pt_regs *regs) 69 { 70 unsigned long sp, next_sp; 71 unsigned long next_ip; 72 unsigned long lr; 73 long level = 0; 74 struct signal_frame_64 __user *sigframe; 75 unsigned long __user *fp, *uregs; 76 77 next_ip = perf_arch_instruction_pointer(regs); 78 lr = regs->link; 79 sp = regs->gpr[1]; 80 81 while (entry->nr < entry->max_stack) { 82 fp = (unsigned long __user *) sp; 83 if (invalid_user_sp(sp) || read_user_stack_64(fp, &next_sp)) 84 return; 85 if (level > 0 && read_user_stack_64(&fp[2], &next_ip)) 86 return; 87 88 /* 89 * Note: the next_sp - sp >= signal frame size check 90 * is true when next_sp < sp, which can happen when 91 * transitioning from an alternate signal stack to the 92 * normal stack. 93 */ 94 if (next_sp - sp >= sizeof(struct signal_frame_64) && 95 (is_sigreturn_64_address(next_ip, sp) || 96 (level <= 1 && is_sigreturn_64_address(lr, sp))) && 97 sane_signal_64_frame(sp)) { 98 /* 99 * This looks like an signal frame 100 */ 101 sigframe = (struct signal_frame_64 __user *) sp; 102 uregs = sigframe->uc.uc_mcontext.gp_regs; 103 if (read_user_stack_64(&uregs[PT_NIP], &next_ip) || 104 read_user_stack_64(&uregs[PT_LNK], &lr) || 105 read_user_stack_64(&uregs[PT_R1], &sp)) 106 return; 107 level = 0; 108 perf_callchain_store_context(entry, PERF_CONTEXT_USER); 109 perf_callchain_store(entry, next_ip); 110 continue; 111 } 112 113 if (level == 0) 114 next_ip = lr; 115 perf_callchain_store(entry, next_ip); 116 ++level; 117 sp = next_sp; 118 } 119 } 120