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 #include "vdso-asmoffset.h" 25 26 /* Signal handler invocation must be transparent for the code being 27 interrupted. Complete CPU (hart) state is saved on entry and restored 28 before returning from the handler. Process sigmask is also saved to block 29 signals while the handler is running. The handler gets its own stack, 30 which also doubles as storage for the CPU state and sigmask. 31 32 The code below is qemu re-implementation of arch/riscv/kernel/signal.c */ 33 34 struct target_sigcontext { 35 abi_long pc; 36 abi_long gpr[31]; /* x0 is not present, so all offsets must be -1 */ 37 uint64_t fpr[32]; 38 uint32_t fcsr; 39 }; /* cf. riscv-linux:arch/riscv/include/uapi/asm/ptrace.h */ 40 41 QEMU_BUILD_BUG_ON(offsetof(struct target_sigcontext, fpr) != offsetof_freg0); 42 43 struct target_ucontext { 44 abi_ulong uc_flags; 45 abi_ptr uc_link; 46 target_stack_t uc_stack; 47 target_sigset_t uc_sigmask; 48 uint8_t __unused[1024 / 8 - sizeof(target_sigset_t)]; 49 struct target_sigcontext uc_mcontext QEMU_ALIGNED(16); 50 }; 51 52 struct target_rt_sigframe { 53 struct target_siginfo info; 54 struct target_ucontext uc; 55 }; 56 57 QEMU_BUILD_BUG_ON(sizeof(struct target_rt_sigframe) 58 != sizeof_rt_sigframe); 59 QEMU_BUILD_BUG_ON(offsetof(struct target_rt_sigframe, uc.uc_mcontext) 60 != offsetof_uc_mcontext); 61 62 static abi_ulong get_sigframe(struct target_sigaction *ka, 63 CPURISCVState *regs, size_t framesize) 64 { 65 abi_ulong sp = get_sp_from_cpustate(regs); 66 67 /* If we are on the alternate signal stack and would overflow it, don't. 68 Return an always-bogus address instead so we will die with SIGSEGV. */ 69 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) { 70 return -1L; 71 } 72 73 /* This is the X/Open sanctioned signal stack switching. */ 74 sp = target_sigsp(sp, ka) - framesize; 75 sp &= ~0xf; 76 77 return sp; 78 } 79 80 static void setup_sigcontext(struct target_sigcontext *sc, CPURISCVState *env) 81 { 82 int i; 83 84 __put_user(env->pc, &sc->pc); 85 86 for (i = 1; i < 32; i++) { 87 __put_user(env->gpr[i], &sc->gpr[i - 1]); 88 } 89 for (i = 0; i < 32; i++) { 90 __put_user(env->fpr[i], &sc->fpr[i]); 91 } 92 93 uint32_t fcsr = riscv_csr_read(env, CSR_FCSR); 94 __put_user(fcsr, &sc->fcsr); 95 } 96 97 static void setup_ucontext(struct target_ucontext *uc, 98 CPURISCVState *env, target_sigset_t *set) 99 { 100 __put_user(0, &(uc->uc_flags)); 101 __put_user(0, &(uc->uc_link)); 102 103 target_save_altstack(&uc->uc_stack, env); 104 105 int i; 106 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 107 __put_user(set->sig[i], &(uc->uc_sigmask.sig[i])); 108 } 109 110 setup_sigcontext(&uc->uc_mcontext, env); 111 } 112 113 void setup_rt_frame(int sig, struct target_sigaction *ka, 114 target_siginfo_t *info, 115 target_sigset_t *set, CPURISCVState *env) 116 { 117 abi_ulong frame_addr; 118 struct target_rt_sigframe *frame; 119 120 frame_addr = get_sigframe(ka, env, sizeof(*frame)); 121 trace_user_setup_rt_frame(env, frame_addr); 122 123 if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { 124 goto badframe; 125 } 126 127 setup_ucontext(&frame->uc, env, set); 128 frame->info = *info; 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] = default_rt_sigreturn; 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 target_restore_altstack(&frame->uc.uc_stack, env); 195 196 unlock_user_struct(frame, frame_addr, 0); 197 return -QEMU_ESIGRETURN; 198 199 badframe: 200 unlock_user_struct(frame, frame_addr, 0); 201 force_sig(TARGET_SIGSEGV); 202 return 0; 203 } 204 205 void setup_sigtramp(abi_ulong sigtramp_page) 206 { 207 uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0); 208 assert(tramp != NULL); 209 210 __put_user(0x08b00893, tramp + 0); /* li a7, 139 = __NR_rt_sigreturn */ 211 __put_user(0x00000073, tramp + 1); /* ecall */ 212 213 default_rt_sigreturn = sigtramp_page; 214 unlock_user(tramp, sigtramp_page, 8); 215 } 216