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 struct x86_perf_regs *perf_regs; 63 64 if (idx >= PERF_REG_X86_XMM0 && idx < PERF_REG_X86_XMM_MAX) { 65 perf_regs = container_of(regs, struct x86_perf_regs, regs); 66 if (!perf_regs->xmm_regs) 67 return 0; 68 return perf_regs->xmm_regs[idx - PERF_REG_X86_XMM0]; 69 } 70 71 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset))) 72 return 0; 73 74 return regs_get_register(regs, pt_regs_offset[idx]); 75 } 76 77 #define PERF_REG_X86_RESERVED (((1ULL << PERF_REG_X86_XMM0) - 1) & \ 78 ~((1ULL << PERF_REG_X86_MAX) - 1)) 79 80 #ifdef CONFIG_X86_32 81 #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_R8) | \ 82 (1ULL << PERF_REG_X86_R9) | \ 83 (1ULL << PERF_REG_X86_R10) | \ 84 (1ULL << PERF_REG_X86_R11) | \ 85 (1ULL << PERF_REG_X86_R12) | \ 86 (1ULL << PERF_REG_X86_R13) | \ 87 (1ULL << PERF_REG_X86_R14) | \ 88 (1ULL << PERF_REG_X86_R15)) 89 90 int perf_reg_validate(u64 mask) 91 { 92 if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED))) 93 return -EINVAL; 94 95 return 0; 96 } 97 98 u64 perf_reg_abi(struct task_struct *task) 99 { 100 return PERF_SAMPLE_REGS_ABI_32; 101 } 102 103 void perf_get_regs_user(struct perf_regs *regs_user, 104 struct pt_regs *regs) 105 { 106 regs_user->regs = task_pt_regs(current); 107 regs_user->abi = perf_reg_abi(current); 108 } 109 #else /* CONFIG_X86_64 */ 110 #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \ 111 (1ULL << PERF_REG_X86_ES) | \ 112 (1ULL << PERF_REG_X86_FS) | \ 113 (1ULL << PERF_REG_X86_GS)) 114 115 int perf_reg_validate(u64 mask) 116 { 117 if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED))) 118 return -EINVAL; 119 120 return 0; 121 } 122 123 u64 perf_reg_abi(struct task_struct *task) 124 { 125 if (!user_64bit_mode(task_pt_regs(task))) 126 return PERF_SAMPLE_REGS_ABI_32; 127 else 128 return PERF_SAMPLE_REGS_ABI_64; 129 } 130 131 static DEFINE_PER_CPU(struct pt_regs, nmi_user_regs); 132 133 void perf_get_regs_user(struct perf_regs *regs_user, 134 struct pt_regs *regs) 135 { 136 struct pt_regs *regs_user_copy = this_cpu_ptr(&nmi_user_regs); 137 struct pt_regs *user_regs = task_pt_regs(current); 138 139 if (!in_nmi()) { 140 regs_user->regs = user_regs; 141 regs_user->abi = perf_reg_abi(current); 142 return; 143 } 144 145 /* 146 * If we're in an NMI that interrupted task_pt_regs setup, then 147 * we can't sample user regs at all. This check isn't really 148 * sufficient, though, as we could be in an NMI inside an interrupt 149 * that happened during task_pt_regs setup. 150 */ 151 if (regs->sp > (unsigned long)&user_regs->r11 && 152 regs->sp <= (unsigned long)(user_regs + 1)) { 153 regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE; 154 regs_user->regs = NULL; 155 return; 156 } 157 158 /* 159 * These registers are always saved on 64-bit syscall entry. 160 * On 32-bit entry points, they are saved too except r8..r11. 161 */ 162 regs_user_copy->ip = user_regs->ip; 163 regs_user_copy->ax = user_regs->ax; 164 regs_user_copy->cx = user_regs->cx; 165 regs_user_copy->dx = user_regs->dx; 166 regs_user_copy->si = user_regs->si; 167 regs_user_copy->di = user_regs->di; 168 regs_user_copy->r8 = user_regs->r8; 169 regs_user_copy->r9 = user_regs->r9; 170 regs_user_copy->r10 = user_regs->r10; 171 regs_user_copy->r11 = user_regs->r11; 172 regs_user_copy->orig_ax = user_regs->orig_ax; 173 regs_user_copy->flags = user_regs->flags; 174 regs_user_copy->sp = user_regs->sp; 175 regs_user_copy->cs = user_regs->cs; 176 regs_user_copy->ss = user_regs->ss; 177 /* 178 * Store user space frame-pointer value on sample 179 * to facilitate stack unwinding for cases when 180 * user space executable code has such support 181 * enabled at compile time: 182 */ 183 regs_user_copy->bp = user_regs->bp; 184 185 regs_user_copy->bx = -1; 186 regs_user_copy->r12 = -1; 187 regs_user_copy->r13 = -1; 188 regs_user_copy->r14 = -1; 189 regs_user_copy->r15 = -1; 190 /* 191 * For this to be at all useful, we need a reasonable guess for 192 * the ABI. Be careful: we're in NMI context, and we're 193 * considering current to be the current task, so we should 194 * be careful not to look at any other percpu variables that might 195 * change during context switches. 196 */ 197 regs_user->abi = user_64bit_mode(user_regs) ? 198 PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32; 199 200 regs_user->regs = regs_user_copy; 201 } 202 #endif /* CONFIG_X86_32 */ 203