1 /* 2 * Emulation of Linux signals 3 * 4 * Copyright (c) 2003 Fabrice Bellard 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, see <http://www.gnu.org/licenses/>. 18 */ 19 #include "qemu/osdep.h" 20 #include "qemu.h" 21 #include "user-internals.h" 22 #include "signal-common.h" 23 #include "linux-user/trace.h" 24 25 /* Signal handler invocation must be transparent for the code being 26 interrupted. Complete CPU (hart) state is saved on entry and restored 27 before returning from the handler. Process sigmask is also saved to block 28 signals while the handler is running. The handler gets its own stack, 29 which also doubles as storage for the CPU state and sigmask. 30 31 The code below is qemu re-implementation of arch/riscv/kernel/signal.c */ 32 33 struct target_sigcontext { 34 abi_long pc; 35 abi_long gpr[31]; /* x0 is not present, so all offsets must be -1 */ 36 uint64_t fpr[32]; 37 uint32_t fcsr; 38 }; /* cf. riscv-linux:arch/riscv/include/uapi/asm/ptrace.h */ 39 40 struct target_ucontext { 41 abi_ulong uc_flags; 42 abi_ptr uc_link; 43 target_stack_t uc_stack; 44 target_sigset_t uc_sigmask; 45 uint8_t __unused[1024 / 8 - sizeof(target_sigset_t)]; 46 struct target_sigcontext uc_mcontext QEMU_ALIGNED(16); 47 }; 48 49 struct target_rt_sigframe { 50 struct target_siginfo info; 51 struct target_ucontext uc; 52 }; 53 54 static abi_ulong get_sigframe(struct target_sigaction *ka, 55 CPURISCVState *regs, size_t framesize) 56 { 57 abi_ulong sp = get_sp_from_cpustate(regs); 58 59 /* If we are on the alternate signal stack and would overflow it, don't. 60 Return an always-bogus address instead so we will die with SIGSEGV. */ 61 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) { 62 return -1L; 63 } 64 65 /* This is the X/Open sanctioned signal stack switching. */ 66 sp = target_sigsp(sp, ka) - framesize; 67 sp &= ~0xf; 68 69 return sp; 70 } 71 72 static void setup_sigcontext(struct target_sigcontext *sc, CPURISCVState *env) 73 { 74 int i; 75 76 __put_user(env->pc, &sc->pc); 77 78 for (i = 1; i < 32; i++) { 79 __put_user(env->gpr[i], &sc->gpr[i - 1]); 80 } 81 for (i = 0; i < 32; i++) { 82 __put_user(env->fpr[i], &sc->fpr[i]); 83 } 84 85 uint32_t fcsr = riscv_csr_read(env, CSR_FCSR); 86 __put_user(fcsr, &sc->fcsr); 87 } 88 89 static void setup_ucontext(struct target_ucontext *uc, 90 CPURISCVState *env, target_sigset_t *set) 91 { 92 __put_user(0, &(uc->uc_flags)); 93 __put_user(0, &(uc->uc_link)); 94 95 target_save_altstack(&uc->uc_stack, env); 96 97 int i; 98 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 99 __put_user(set->sig[i], &(uc->uc_sigmask.sig[i])); 100 } 101 102 setup_sigcontext(&uc->uc_mcontext, env); 103 } 104 105 void setup_rt_frame(int sig, struct target_sigaction *ka, 106 target_siginfo_t *info, 107 target_sigset_t *set, CPURISCVState *env) 108 { 109 abi_ulong frame_addr; 110 struct target_rt_sigframe *frame; 111 112 frame_addr = get_sigframe(ka, env, sizeof(*frame)); 113 trace_user_setup_rt_frame(env, frame_addr); 114 115 if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { 116 goto badframe; 117 } 118 119 setup_ucontext(&frame->uc, env, set); 120 tswap_siginfo(&frame->info, info); 121 122 env->pc = ka->_sa_handler; 123 env->gpr[xSP] = frame_addr; 124 env->gpr[xA0] = sig; 125 env->gpr[xA1] = frame_addr + offsetof(struct target_rt_sigframe, info); 126 env->gpr[xA2] = frame_addr + offsetof(struct target_rt_sigframe, uc); 127 env->gpr[xRA] = default_rt_sigreturn; 128 129 return; 130 131 badframe: 132 unlock_user_struct(frame, frame_addr, 1); 133 if (sig == TARGET_SIGSEGV) { 134 ka->_sa_handler = TARGET_SIG_DFL; 135 } 136 force_sig(TARGET_SIGSEGV); 137 } 138 139 static void restore_sigcontext(CPURISCVState *env, struct target_sigcontext *sc) 140 { 141 int i; 142 143 __get_user(env->pc, &sc->pc); 144 145 for (i = 1; i < 32; ++i) { 146 __get_user(env->gpr[i], &sc->gpr[i - 1]); 147 } 148 for (i = 0; i < 32; ++i) { 149 __get_user(env->fpr[i], &sc->fpr[i]); 150 } 151 152 uint32_t fcsr; 153 __get_user(fcsr, &sc->fcsr); 154 riscv_csr_write(env, CSR_FCSR, fcsr); 155 } 156 157 static void restore_ucontext(CPURISCVState *env, struct target_ucontext *uc) 158 { 159 sigset_t blocked; 160 target_sigset_t target_set; 161 int i; 162 163 target_sigemptyset(&target_set); 164 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 165 __get_user(target_set.sig[i], &(uc->uc_sigmask.sig[i])); 166 } 167 168 target_to_host_sigset_internal(&blocked, &target_set); 169 set_sigmask(&blocked); 170 171 restore_sigcontext(env, &uc->uc_mcontext); 172 } 173 174 long do_rt_sigreturn(CPURISCVState *env) 175 { 176 struct target_rt_sigframe *frame; 177 abi_ulong frame_addr; 178 179 frame_addr = env->gpr[xSP]; 180 trace_user_do_sigreturn(env, frame_addr); 181 if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) { 182 goto badframe; 183 } 184 185 restore_ucontext(env, &frame->uc); 186 target_restore_altstack(&frame->uc.uc_stack, env); 187 188 unlock_user_struct(frame, frame_addr, 0); 189 return -QEMU_ESIGRETURN; 190 191 badframe: 192 unlock_user_struct(frame, frame_addr, 0); 193 force_sig(TARGET_SIGSEGV); 194 return 0; 195 } 196 197 void setup_sigtramp(abi_ulong sigtramp_page) 198 { 199 uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0); 200 assert(tramp != NULL); 201 202 __put_user(0x08b00893, tramp + 0); /* li a7, 139 = __NR_rt_sigreturn */ 203 __put_user(0x00000073, tramp + 1); /* ecall */ 204 205 default_rt_sigreturn = sigtramp_page; 206 unlock_user(tramp, sigtramp_page, 8); 207 } 208