linux-user/riscv/signal.c

   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 }