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 unsigned long uc_flags; 42 struct target_ucontext *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 68 /* XXX: kernel aligns with 0xf ? */ 69 sp &= ~3UL; /* align sp on 4-byte boundary */ 70 71 return sp; 72 } 73 74 static void setup_sigcontext(struct target_sigcontext *sc, CPURISCVState *env) 75 { 76 int i; 77 78 __put_user(env->pc, &sc->pc); 79 80 for (i = 1; i < 32; i++) { 81 __put_user(env->gpr[i], &sc->gpr[i - 1]); 82 } 83 for (i = 0; i < 32; i++) { 84 __put_user(env->fpr[i], &sc->fpr[i]); 85 } 86 87 uint32_t fcsr = riscv_csr_read(env, CSR_FCSR); 88 __put_user(fcsr, &sc->fcsr); 89 } 90 91 static void setup_ucontext(struct target_ucontext *uc, 92 CPURISCVState *env, target_sigset_t *set) 93 { 94 __put_user(0, &(uc->uc_flags)); 95 __put_user(0, &(uc->uc_link)); 96 97 target_save_altstack(&uc->uc_stack, env); 98 99 int i; 100 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 101 __put_user(set->sig[i], &(uc->uc_sigmask.sig[i])); 102 } 103 104 setup_sigcontext(&uc->uc_mcontext, env); 105 } 106 107 void setup_rt_frame(int sig, struct target_sigaction *ka, 108 target_siginfo_t *info, 109 target_sigset_t *set, CPURISCVState *env) 110 { 111 abi_ulong frame_addr; 112 struct target_rt_sigframe *frame; 113 114 frame_addr = get_sigframe(ka, env, sizeof(*frame)); 115 trace_user_setup_rt_frame(env, frame_addr); 116 117 if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { 118 goto badframe; 119 } 120 121 setup_ucontext(&frame->uc, env, set); 122 tswap_siginfo(&frame->info, info); 123 124 env->pc = ka->_sa_handler; 125 env->gpr[xSP] = frame_addr; 126 env->gpr[xA0] = sig; 127 env->gpr[xA1] = frame_addr + offsetof(struct target_rt_sigframe, info); 128 env->gpr[xA2] = frame_addr + offsetof(struct target_rt_sigframe, uc); 129 env->gpr[xRA] = default_rt_sigreturn; 130 131 return; 132 133 badframe: 134 unlock_user_struct(frame, frame_addr, 1); 135 if (sig == TARGET_SIGSEGV) { 136 ka->_sa_handler = TARGET_SIG_DFL; 137 } 138 force_sig(TARGET_SIGSEGV); 139 } 140 141 static void restore_sigcontext(CPURISCVState *env, struct target_sigcontext *sc) 142 { 143 int i; 144 145 __get_user(env->pc, &sc->pc); 146 147 for (i = 1; i < 32; ++i) { 148 __get_user(env->gpr[i], &sc->gpr[i - 1]); 149 } 150 for (i = 0; i < 32; ++i) { 151 __get_user(env->fpr[i], &sc->fpr[i]); 152 } 153 154 uint32_t fcsr; 155 __get_user(fcsr, &sc->fcsr); 156 riscv_csr_write(env, CSR_FCSR, fcsr); 157 } 158 159 static void restore_ucontext(CPURISCVState *env, struct target_ucontext *uc) 160 { 161 sigset_t blocked; 162 target_sigset_t target_set; 163 int i; 164 165 target_sigemptyset(&target_set); 166 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 167 __get_user(target_set.sig[i], &(uc->uc_sigmask.sig[i])); 168 } 169 170 target_to_host_sigset_internal(&blocked, &target_set); 171 set_sigmask(&blocked); 172 173 restore_sigcontext(env, &uc->uc_mcontext); 174 } 175 176 long do_rt_sigreturn(CPURISCVState *env) 177 { 178 struct target_rt_sigframe *frame; 179 abi_ulong frame_addr; 180 181 frame_addr = env->gpr[xSP]; 182 trace_user_do_sigreturn(env, frame_addr); 183 if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) { 184 goto badframe; 185 } 186 187 restore_ucontext(env, &frame->uc); 188 target_restore_altstack(&frame->uc.uc_stack, env); 189 190 unlock_user_struct(frame, frame_addr, 0); 191 return -QEMU_ESIGRETURN; 192 193 badframe: 194 unlock_user_struct(frame, frame_addr, 0); 195 force_sig(TARGET_SIGSEGV); 196 return 0; 197 } 198 199 void setup_sigtramp(abi_ulong sigtramp_page) 200 { 201 uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0); 202 assert(tramp != NULL); 203 204 __put_user(0x08b00893, tramp + 0); /* li a7, 139 = __NR_rt_sigreturn */ 205 __put_user(0x00000073, tramp + 1); /* ecall */ 206 207 default_rt_sigreturn = sigtramp_page; 208 unlock_user(tramp, sigtramp_page, 8); 209 } 210