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 "signal-common.h" 22 #include "linux-user/trace.h" 23 24 /* Signal handler invocation must be transparent for the code being 25 interrupted. Complete CPU (hart) state is saved on entry and restored 26 before returning from the handler. Process sigmask is also saved to block 27 signals while the handler is running. The handler gets its own stack, 28 which also doubles as storage for the CPU state and sigmask. 29 30 The code below is qemu re-implementation of arch/riscv/kernel/signal.c */ 31 32 struct target_sigcontext { 33 abi_long pc; 34 abi_long gpr[31]; /* x0 is not present, so all offsets must be -1 */ 35 uint64_t fpr[32]; 36 uint32_t fcsr; 37 }; /* cf. riscv-linux:arch/riscv/include/uapi/asm/ptrace.h */ 38 39 struct target_ucontext { 40 unsigned long uc_flags; 41 struct target_ucontext *uc_link; 42 target_stack_t uc_stack; 43 struct target_sigcontext uc_mcontext; 44 target_sigset_t uc_sigmask; 45 }; 46 47 struct target_rt_sigframe { 48 uint32_t tramp[2]; /* not in kernel, which uses VDSO instead */ 49 struct target_siginfo info; 50 struct target_ucontext uc; 51 }; 52 53 static abi_ulong get_sigframe(struct target_sigaction *ka, 54 CPURISCVState *regs, size_t framesize) 55 { 56 abi_ulong sp = get_sp_from_cpustate(regs); 57 58 /* If we are on the alternate signal stack and would overflow it, don't. 59 Return an always-bogus address instead so we will die with SIGSEGV. */ 60 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) { 61 return -1L; 62 } 63 64 /* This is the X/Open sanctioned signal stack switching. */ 65 sp = target_sigsp(sp, ka) - framesize; 66 67 /* XXX: kernel aligns with 0xf ? */ 68 sp &= ~3UL; /* align sp on 4-byte boundary */ 69 70 return sp; 71 } 72 73 static void setup_sigcontext(struct target_sigcontext *sc, CPURISCVState *env) 74 { 75 int i; 76 77 __put_user(env->pc, &sc->pc); 78 79 for (i = 1; i < 32; i++) { 80 __put_user(env->gpr[i], &sc->gpr[i - 1]); 81 } 82 for (i = 0; i < 32; i++) { 83 __put_user(env->fpr[i], &sc->fpr[i]); 84 } 85 86 uint32_t fcsr = riscv_csr_read(env, CSR_FCSR); 87 __put_user(fcsr, &sc->fcsr); 88 } 89 90 static void setup_ucontext(struct target_ucontext *uc, 91 CPURISCVState *env, target_sigset_t *set) 92 { 93 __put_user(0, &(uc->uc_flags)); 94 __put_user(0, &(uc->uc_link)); 95 96 target_save_altstack(&uc->uc_stack, env); 97 98 int i; 99 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 100 __put_user(set->sig[i], &(uc->uc_sigmask.sig[i])); 101 } 102 103 setup_sigcontext(&uc->uc_mcontext, env); 104 } 105 106 static inline void install_sigtramp(uint32_t *tramp) 107 { 108 __put_user(0x08b00893, tramp + 0); /* li a7, 139 = __NR_rt_sigreturn */ 109 __put_user(0x00000073, tramp + 1); /* ecall */ 110 } 111 112 void setup_rt_frame(int sig, struct target_sigaction *ka, 113 target_siginfo_t *info, 114 target_sigset_t *set, CPURISCVState *env) 115 { 116 abi_ulong frame_addr; 117 struct target_rt_sigframe *frame; 118 119 frame_addr = get_sigframe(ka, env, sizeof(*frame)); 120 trace_user_setup_rt_frame(env, frame_addr); 121 122 if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { 123 goto badframe; 124 } 125 126 setup_ucontext(&frame->uc, env, set); 127 tswap_siginfo(&frame->info, info); 128 install_sigtramp(frame->tramp); 129 130 env->pc = ka->_sa_handler; 131 env->gpr[xSP] = frame_addr; 132 env->gpr[xA0] = sig; 133 env->gpr[xA1] = frame_addr + offsetof(struct target_rt_sigframe, info); 134 env->gpr[xA2] = frame_addr + offsetof(struct target_rt_sigframe, uc); 135 env->gpr[xRA] = frame_addr + offsetof(struct target_rt_sigframe, tramp); 136 137 return; 138 139 badframe: 140 unlock_user_struct(frame, frame_addr, 1); 141 if (sig == TARGET_SIGSEGV) { 142 ka->_sa_handler = TARGET_SIG_DFL; 143 } 144 force_sig(TARGET_SIGSEGV); 145 } 146 147 static void restore_sigcontext(CPURISCVState *env, struct target_sigcontext *sc) 148 { 149 int i; 150 151 __get_user(env->pc, &sc->pc); 152 153 for (i = 1; i < 32; ++i) { 154 __get_user(env->gpr[i], &sc->gpr[i - 1]); 155 } 156 for (i = 0; i < 32; ++i) { 157 __get_user(env->fpr[i], &sc->fpr[i]); 158 } 159 160 uint32_t fcsr; 161 __get_user(fcsr, &sc->fcsr); 162 riscv_csr_write(env, CSR_FCSR, fcsr); 163 } 164 165 static void restore_ucontext(CPURISCVState *env, struct target_ucontext *uc) 166 { 167 sigset_t blocked; 168 target_sigset_t target_set; 169 int i; 170 171 target_sigemptyset(&target_set); 172 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 173 __get_user(target_set.sig[i], &(uc->uc_sigmask.sig[i])); 174 } 175 176 target_to_host_sigset_internal(&blocked, &target_set); 177 set_sigmask(&blocked); 178 179 restore_sigcontext(env, &uc->uc_mcontext); 180 } 181 182 long do_rt_sigreturn(CPURISCVState *env) 183 { 184 struct target_rt_sigframe *frame; 185 abi_ulong frame_addr; 186 187 frame_addr = env->gpr[xSP]; 188 trace_user_do_sigreturn(env, frame_addr); 189 if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) { 190 goto badframe; 191 } 192 193 restore_ucontext(env, &frame->uc); 194 195 if (do_sigaltstack(frame_addr + offsetof(struct target_rt_sigframe, 196 uc.uc_stack), 0, get_sp_from_cpustate(env)) == -EFAULT) { 197 goto badframe; 198 } 199 200 unlock_user_struct(frame, frame_addr, 0); 201 return -TARGET_QEMU_ESIGRETURN; 202 203 badframe: 204 unlock_user_struct(frame, frame_addr, 0); 205 force_sig(TARGET_SIGSEGV); 206 return 0; 207 } 208