1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/errno.h> 3 #include <linux/kernel.h> 4 #include <linux/sched.h> 5 #include <linux/sched/task_stack.h> 6 #include <linux/perf_event.h> 7 #include <linux/bug.h> 8 #include <linux/stddef.h> 9 #include <asm/perf_regs.h> 10 #include <asm/ptrace.h> 11 12 #ifdef CONFIG_X86_32 13 #define PERF_REG_X86_MAX PERF_REG_X86_32_MAX 14 #else 15 #define PERF_REG_X86_MAX PERF_REG_X86_64_MAX 16 #endif 17 18 #define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r) 19 20 static unsigned int pt_regs_offset[PERF_REG_X86_MAX] = { 21 PT_REGS_OFFSET(PERF_REG_X86_AX, ax), 22 PT_REGS_OFFSET(PERF_REG_X86_BX, bx), 23 PT_REGS_OFFSET(PERF_REG_X86_CX, cx), 24 PT_REGS_OFFSET(PERF_REG_X86_DX, dx), 25 PT_REGS_OFFSET(PERF_REG_X86_SI, si), 26 PT_REGS_OFFSET(PERF_REG_X86_DI, di), 27 PT_REGS_OFFSET(PERF_REG_X86_BP, bp), 28 PT_REGS_OFFSET(PERF_REG_X86_SP, sp), 29 PT_REGS_OFFSET(PERF_REG_X86_IP, ip), 30 PT_REGS_OFFSET(PERF_REG_X86_FLAGS, flags), 31 PT_REGS_OFFSET(PERF_REG_X86_CS, cs), 32 PT_REGS_OFFSET(PERF_REG_X86_SS, ss), 33 #ifdef CONFIG_X86_32 34 PT_REGS_OFFSET(PERF_REG_X86_DS, ds), 35 PT_REGS_OFFSET(PERF_REG_X86_ES, es), 36 PT_REGS_OFFSET(PERF_REG_X86_FS, fs), 37 PT_REGS_OFFSET(PERF_REG_X86_GS, gs), 38 #else 39 /* 40 * The pt_regs struct does not store 41 * ds, es, fs, gs in 64 bit mode. 42 */ 43 (unsigned int) -1, 44 (unsigned int) -1, 45 (unsigned int) -1, 46 (unsigned int) -1, 47 #endif 48 #ifdef CONFIG_X86_64 49 PT_REGS_OFFSET(PERF_REG_X86_R8, r8), 50 PT_REGS_OFFSET(PERF_REG_X86_R9, r9), 51 PT_REGS_OFFSET(PERF_REG_X86_R10, r10), 52 PT_REGS_OFFSET(PERF_REG_X86_R11, r11), 53 PT_REGS_OFFSET(PERF_REG_X86_R12, r12), 54 PT_REGS_OFFSET(PERF_REG_X86_R13, r13), 55 PT_REGS_OFFSET(PERF_REG_X86_R14, r14), 56 PT_REGS_OFFSET(PERF_REG_X86_R15, r15), 57 #endif 58 }; 59 60 u64 perf_reg_value(struct pt_regs *regs, int idx) 61 { 62 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset))) 63 return 0; 64 65 return regs_get_register(regs, pt_regs_offset[idx]); 66 } 67 68 #define REG_RESERVED (~((1ULL << PERF_REG_X86_MAX) - 1ULL)) 69 70 #ifdef CONFIG_X86_32 71 int perf_reg_validate(u64 mask) 72 { 73 if (!mask || mask & REG_RESERVED) 74 return -EINVAL; 75 76 return 0; 77 } 78 79 u64 perf_reg_abi(struct task_struct *task) 80 { 81 return PERF_SAMPLE_REGS_ABI_32; 82 } 83 84 void perf_get_regs_user(struct perf_regs *regs_user, 85 struct pt_regs *regs, 86 struct pt_regs *regs_user_copy) 87 { 88 regs_user->regs = task_pt_regs(current); 89 regs_user->abi = perf_reg_abi(current); 90 } 91 #else /* CONFIG_X86_64 */ 92 #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \ 93 (1ULL << PERF_REG_X86_ES) | \ 94 (1ULL << PERF_REG_X86_FS) | \ 95 (1ULL << PERF_REG_X86_GS)) 96 97 int perf_reg_validate(u64 mask) 98 { 99 if (!mask || mask & REG_RESERVED) 100 return -EINVAL; 101 102 if (mask & REG_NOSUPPORT) 103 return -EINVAL; 104 105 return 0; 106 } 107 108 u64 perf_reg_abi(struct task_struct *task) 109 { 110 if (test_tsk_thread_flag(task, TIF_IA32)) 111 return PERF_SAMPLE_REGS_ABI_32; 112 else 113 return PERF_SAMPLE_REGS_ABI_64; 114 } 115 116 void perf_get_regs_user(struct perf_regs *regs_user, 117 struct pt_regs *regs, 118 struct pt_regs *regs_user_copy) 119 { 120 struct pt_regs *user_regs = task_pt_regs(current); 121 122 /* 123 * If we're in an NMI that interrupted task_pt_regs setup, then 124 * we can't sample user regs at all. This check isn't really 125 * sufficient, though, as we could be in an NMI inside an interrupt 126 * that happened during task_pt_regs setup. 127 */ 128 if (regs->sp > (unsigned long)&user_regs->r11 && 129 regs->sp <= (unsigned long)(user_regs + 1)) { 130 regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE; 131 regs_user->regs = NULL; 132 return; 133 } 134 135 /* 136 * These registers are always saved on 64-bit syscall entry. 137 * On 32-bit entry points, they are saved too except r8..r11. 138 */ 139 regs_user_copy->ip = user_regs->ip; 140 regs_user_copy->ax = user_regs->ax; 141 regs_user_copy->cx = user_regs->cx; 142 regs_user_copy->dx = user_regs->dx; 143 regs_user_copy->si = user_regs->si; 144 regs_user_copy->di = user_regs->di; 145 regs_user_copy->r8 = user_regs->r8; 146 regs_user_copy->r9 = user_regs->r9; 147 regs_user_copy->r10 = user_regs->r10; 148 regs_user_copy->r11 = user_regs->r11; 149 regs_user_copy->orig_ax = user_regs->orig_ax; 150 regs_user_copy->flags = user_regs->flags; 151 regs_user_copy->sp = user_regs->sp; 152 regs_user_copy->cs = user_regs->cs; 153 regs_user_copy->ss = user_regs->ss; 154 155 /* 156 * Most system calls don't save these registers, don't report them. 157 */ 158 regs_user_copy->bx = -1; 159 regs_user_copy->bp = -1; 160 regs_user_copy->r12 = -1; 161 regs_user_copy->r13 = -1; 162 regs_user_copy->r14 = -1; 163 regs_user_copy->r15 = -1; 164 165 /* 166 * For this to be at all useful, we need a reasonable guess for 167 * the ABI. Be careful: we're in NMI context, and we're 168 * considering current to be the current task, so we should 169 * be careful not to look at any other percpu variables that might 170 * change during context switches. 171 */ 172 regs_user->abi = user_64bit_mode(user_regs) ? 173 PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32; 174 175 regs_user->regs = regs_user_copy; 176 } 177 #endif /* CONFIG_X86_32 */ 178