| 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 | uint64_t fcsr; |
| 94 | riscv_csr_read_i64(env, CSR_FCSR, &fcsr); |
| 95 | __put_user(fcsr, &sc->fcsr); |
| 96 | } |
| 97 | |
| 98 | static void setup_ucontext(struct target_ucontext *uc, |
| 99 | CPURISCVState *env, target_sigset_t *set) |
| 100 | { |
| 101 | __put_user(0, &(uc->uc_flags)); |
| 102 | __put_user(0, &(uc->uc_link)); |
| 103 | |
| 104 | target_save_altstack(&uc->uc_stack, env); |
| 105 | |
| 106 | int i; |
| 107 | for (i = 0; i < TARGET_NSIG_WORDS; i++) { |
| 108 | __put_user(set->sig[i], &(uc->uc_sigmask.sig[i])); |
| 109 | } |
| 110 | |
| 111 | setup_sigcontext(&uc->uc_mcontext, env); |
| 112 | } |
| 113 | |
| 114 | void setup_rt_frame(int sig, struct target_sigaction *ka, |
| 115 | target_siginfo_t *info, |
| 116 | target_sigset_t *set, CPURISCVState *env) |
| 117 | { |
| 118 | abi_ulong frame_addr; |
| 119 | struct target_rt_sigframe *frame; |
| 120 | |
| 121 | frame_addr = get_sigframe(ka, env, sizeof(*frame)); |
| 122 | trace_user_setup_rt_frame(env, frame_addr); |
| 123 | |
| 124 | if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { |
| 125 | goto badframe; |
| 126 | } |
| 127 | |
| 128 | setup_ucontext(&frame->uc, env, set); |
| 129 | frame->info = *info; |
| 130 | |
| 131 | env->pc = ka->_sa_handler; |
| 132 | env->gpr[xSP] = frame_addr; |
| 133 | env->gpr[xA0] = sig; |
| 134 | env->gpr[xA1] = frame_addr + offsetof(struct target_rt_sigframe, info); |
| 135 | env->gpr[xA2] = frame_addr + offsetof(struct target_rt_sigframe, uc); |
| 136 | env->gpr[xRA] = default_rt_sigreturn; |
| 137 | |
| 138 | return; |
| 139 | |
| 140 | badframe: |
| 141 | unlock_user_struct(frame, frame_addr, 1); |
| 142 | if (sig == TARGET_SIGSEGV) { |
| 143 | ka->_sa_handler = TARGET_SIG_DFL; |
| 144 | } |
| 145 | force_sig(TARGET_SIGSEGV); |
| 146 | } |
| 147 | |
| 148 | static void restore_sigcontext(CPURISCVState *env, struct target_sigcontext *sc) |
| 149 | { |
| 150 | int i; |
| 151 | |
| 152 | __get_user(env->pc, &sc->pc); |
| 153 | |
| 154 | for (i = 1; i < 32; ++i) { |
| 155 | __get_user(env->gpr[i], &sc->gpr[i - 1]); |
| 156 | } |
| 157 | for (i = 0; i < 32; ++i) { |
| 158 | __get_user(env->fpr[i], &sc->fpr[i]); |
| 159 | } |
| 160 | |
| 161 | uint32_t fcsr; |
| 162 | __get_user(fcsr, &sc->fcsr); |
| 163 | riscv_csr_write_i64(env, CSR_FCSR, fcsr); |
| 164 | } |
| 165 | |
| 166 | static void restore_ucontext(CPURISCVState *env, struct target_ucontext *uc) |
| 167 | { |
| 168 | sigset_t blocked; |
| 169 | target_sigset_t target_set; |
| 170 | int i; |
| 171 | |
| 172 | target_sigemptyset(&target_set); |
| 173 | for (i = 0; i < TARGET_NSIG_WORDS; i++) { |
| 174 | __get_user(target_set.sig[i], &(uc->uc_sigmask.sig[i])); |
| 175 | } |
| 176 | |
| 177 | target_to_host_sigset_internal(&blocked, &target_set); |
| 178 | set_sigmask(&blocked); |
| 179 | |
| 180 | restore_sigcontext(env, &uc->uc_mcontext); |
| 181 | } |
| 182 | |
| 183 | long do_rt_sigreturn(CPURISCVState *env) |
| 184 | { |
| 185 | struct target_rt_sigframe *frame; |
| 186 | abi_ulong frame_addr; |
| 187 | |
| 188 | frame_addr = env->gpr[xSP]; |
| 189 | trace_user_do_sigreturn(env, frame_addr); |
| 190 | if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) { |
| 191 | goto badframe; |
| 192 | } |
| 193 | |
| 194 | restore_ucontext(env, &frame->uc); |
| 195 | target_restore_altstack(&frame->uc.uc_stack, env); |
| 196 | |
| 197 | unlock_user_struct(frame, frame_addr, 0); |
| 198 | return -QEMU_ESIGRETURN; |
| 199 | |
| 200 | badframe: |
| 201 | unlock_user_struct(frame, frame_addr, 0); |
| 202 | force_sig(TARGET_SIGSEGV); |
| 203 | return 0; |
| 204 | } |
| 205 | |
| 206 | void setup_sigtramp(abi_ulong sigtramp_page) |
| 207 | { |
| 208 | uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0); |
| 209 | assert(tramp != NULL); |
| 210 | |
| 211 | __put_user(0x08b00893, tramp + 0); /* li a7, 139 = __NR_rt_sigreturn */ |
| 212 | __put_user(0x00000073, tramp + 1); /* ecall */ |
| 213 | |
| 214 | default_rt_sigreturn = sigtramp_page; |
| 215 | unlock_user(tramp, sigtramp_page, 8); |
| 216 | } |