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signal.c (21059B)


      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 /* Size of dummy stack frame allocated when calling signal handler.
     26    See arch/powerpc/include/asm/ptrace.h.  */
     27 #if defined(TARGET_PPC64)
     28 #define SIGNAL_FRAMESIZE 128
     29 #else
     30 #define SIGNAL_FRAMESIZE 64
     31 #endif
     32 
     33 /* See arch/powerpc/include/asm/ucontext.h.  Only used for 32-bit PPC;
     34    on 64-bit PPC, sigcontext and mcontext are one and the same.  */
     35 struct target_mcontext {
     36     target_ulong mc_gregs[48];
     37     /* Includes fpscr.  */
     38     uint64_t mc_fregs[33];
     39 
     40 #if defined(TARGET_PPC64)
     41     /* Pointer to the vector regs */
     42     target_ulong v_regs;
     43     /*
     44      * On ppc64, this mcontext structure is naturally *unaligned*,
     45      * or rather it is aligned on a 8 bytes boundary but not on
     46      * a 16 byte boundary.  This pad fixes it up.  This is why we
     47      * cannot use ppc_avr_t, which would force alignment.  This is
     48      * also why the vector regs are referenced in the ABI by the
     49      * v_regs pointer above so any amount of padding can be added here.
     50      */
     51     target_ulong pad;
     52     /* VSCR and VRSAVE are saved separately.  Also reserve space for VSX. */
     53     struct {
     54         uint64_t altivec[34 + 16][2];
     55     } mc_vregs;
     56 #else
     57     target_ulong mc_pad[2];
     58 
     59     /* We need to handle Altivec and SPE at the same time, which no
     60        kernel needs to do.  Fortunately, the kernel defines this bit to
     61        be Altivec-register-large all the time, rather than trying to
     62        twiddle it based on the specific platform.  */
     63     union {
     64         /* SPE vector registers.  One extra for SPEFSCR.  */
     65         uint32_t spe[33];
     66         /*
     67          * Altivec vector registers.  One extra for VRSAVE.
     68          * On ppc32, we are already aligned to 16 bytes.  We could
     69          * use ppc_avr_t, but choose to share the same type as ppc64.
     70          */
     71         uint64_t altivec[33][2];
     72     } mc_vregs;
     73 #endif
     74 };
     75 
     76 /* See arch/powerpc/include/asm/sigcontext.h.  */
     77 struct target_sigcontext {
     78     target_ulong _unused[4];
     79     int32_t signal;
     80 #if defined(TARGET_PPC64)
     81     int32_t pad0;
     82 #endif
     83     target_ulong handler;
     84     target_ulong oldmask;
     85     target_ulong regs;      /* struct pt_regs __user * */
     86 #if defined(TARGET_PPC64)
     87     struct target_mcontext mcontext;
     88 #endif
     89 };
     90 
     91 /* Indices for target_mcontext.mc_gregs, below.
     92    See arch/powerpc/include/asm/ptrace.h for details.  */
     93 enum {
     94     TARGET_PT_R0 = 0,
     95     TARGET_PT_R1 = 1,
     96     TARGET_PT_R2 = 2,
     97     TARGET_PT_R3 = 3,
     98     TARGET_PT_R4 = 4,
     99     TARGET_PT_R5 = 5,
    100     TARGET_PT_R6 = 6,
    101     TARGET_PT_R7 = 7,
    102     TARGET_PT_R8 = 8,
    103     TARGET_PT_R9 = 9,
    104     TARGET_PT_R10 = 10,
    105     TARGET_PT_R11 = 11,
    106     TARGET_PT_R12 = 12,
    107     TARGET_PT_R13 = 13,
    108     TARGET_PT_R14 = 14,
    109     TARGET_PT_R15 = 15,
    110     TARGET_PT_R16 = 16,
    111     TARGET_PT_R17 = 17,
    112     TARGET_PT_R18 = 18,
    113     TARGET_PT_R19 = 19,
    114     TARGET_PT_R20 = 20,
    115     TARGET_PT_R21 = 21,
    116     TARGET_PT_R22 = 22,
    117     TARGET_PT_R23 = 23,
    118     TARGET_PT_R24 = 24,
    119     TARGET_PT_R25 = 25,
    120     TARGET_PT_R26 = 26,
    121     TARGET_PT_R27 = 27,
    122     TARGET_PT_R28 = 28,
    123     TARGET_PT_R29 = 29,
    124     TARGET_PT_R30 = 30,
    125     TARGET_PT_R31 = 31,
    126     TARGET_PT_NIP = 32,
    127     TARGET_PT_MSR = 33,
    128     TARGET_PT_ORIG_R3 = 34,
    129     TARGET_PT_CTR = 35,
    130     TARGET_PT_LNK = 36,
    131     TARGET_PT_XER = 37,
    132     TARGET_PT_CCR = 38,
    133     /* Yes, there are two registers with #39.  One is 64-bit only.  */
    134     TARGET_PT_MQ = 39,
    135     TARGET_PT_SOFTE = 39,
    136     TARGET_PT_TRAP = 40,
    137     TARGET_PT_DAR = 41,
    138     TARGET_PT_DSISR = 42,
    139     TARGET_PT_RESULT = 43,
    140     TARGET_PT_REGS_COUNT = 44
    141 };
    142 
    143 
    144 struct target_ucontext {
    145     target_ulong tuc_flags;
    146     target_ulong tuc_link;    /* ucontext_t __user * */
    147     struct target_sigaltstack tuc_stack;
    148 #if !defined(TARGET_PPC64)
    149     int32_t tuc_pad[7];
    150     target_ulong tuc_regs;    /* struct mcontext __user *
    151                                 points to uc_mcontext field */
    152 #endif
    153     target_sigset_t tuc_sigmask;
    154 #if defined(TARGET_PPC64)
    155     target_sigset_t unused[15]; /* Allow for uc_sigmask growth */
    156     struct target_sigcontext tuc_sigcontext;
    157 #else
    158     int32_t tuc_maskext[30];
    159     int32_t tuc_pad2[3];
    160     struct target_mcontext tuc_mcontext;
    161 #endif
    162 };
    163 
    164 /* See arch/powerpc/kernel/signal_32.c.  */
    165 struct target_sigframe {
    166     struct target_sigcontext sctx;
    167     struct target_mcontext mctx;
    168     int32_t abigap[56];
    169 };
    170 
    171 #if defined(TARGET_PPC64)
    172 
    173 #define TARGET_TRAMP_SIZE 6
    174 
    175 struct target_rt_sigframe {
    176     /* sys_rt_sigreturn requires the ucontext be the first field */
    177     struct target_ucontext uc;
    178     target_ulong  _unused[2];
    179     uint32_t trampoline[TARGET_TRAMP_SIZE];
    180     target_ulong pinfo; /* struct siginfo __user * */
    181     target_ulong puc; /* void __user * */
    182     struct target_siginfo info;
    183     /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
    184     char abigap[288];
    185 } __attribute__((aligned(16)));
    186 
    187 #else
    188 
    189 struct target_rt_sigframe {
    190     struct target_siginfo info;
    191     struct target_ucontext uc;
    192     int32_t abigap[56];
    193 };
    194 
    195 #endif
    196 
    197 #if defined(TARGET_PPC64)
    198 
    199 struct target_func_ptr {
    200     target_ulong entry;
    201     target_ulong toc;
    202 };
    203 
    204 #endif
    205 
    206 /* See arch/powerpc/kernel/signal.c.  */
    207 static target_ulong get_sigframe(struct target_sigaction *ka,
    208                                  CPUPPCState *env,
    209                                  int frame_size)
    210 {
    211     target_ulong oldsp;
    212 
    213     oldsp = target_sigsp(get_sp_from_cpustate(env), ka);
    214 
    215     return (oldsp - frame_size) & ~0xFUL;
    216 }
    217 
    218 #if TARGET_BIG_ENDIAN == HOST_BIG_ENDIAN
    219 #define PPC_VEC_HI      0
    220 #define PPC_VEC_LO      1
    221 #else
    222 #define PPC_VEC_HI      1
    223 #define PPC_VEC_LO      0
    224 #endif
    225 
    226 
    227 static void save_user_regs(CPUPPCState *env, struct target_mcontext *frame)
    228 {
    229     target_ulong msr = env->msr;
    230     int i;
    231     uint32_t ccr = 0;
    232 
    233     /* In general, the kernel attempts to be intelligent about what it
    234        needs to save for Altivec/FP/SPE registers.  We don't care that
    235        much, so we just go ahead and save everything.  */
    236 
    237     /* Save general registers.  */
    238     for (i = 0; i < ARRAY_SIZE(env->gpr); i++) {
    239         __put_user(env->gpr[i], &frame->mc_gregs[i]);
    240     }
    241     __put_user(env->nip, &frame->mc_gregs[TARGET_PT_NIP]);
    242     __put_user(env->ctr, &frame->mc_gregs[TARGET_PT_CTR]);
    243     __put_user(env->lr, &frame->mc_gregs[TARGET_PT_LNK]);
    244     __put_user(cpu_read_xer(env), &frame->mc_gregs[TARGET_PT_XER]);
    245 
    246     for (i = 0; i < ARRAY_SIZE(env->crf); i++) {
    247         ccr |= env->crf[i] << (32 - ((i + 1) * 4));
    248     }
    249     __put_user(ccr, &frame->mc_gregs[TARGET_PT_CCR]);
    250 
    251     /* Save Altivec registers if necessary.  */
    252     if (env->insns_flags & PPC_ALTIVEC) {
    253         uint32_t *vrsave;
    254         for (i = 0; i < 32; i++) {
    255             ppc_avr_t *avr = cpu_avr_ptr(env, i);
    256             ppc_avr_t *vreg = (ppc_avr_t *)&frame->mc_vregs.altivec[i];
    257 
    258             __put_user(avr->u64[PPC_VEC_HI], &vreg->u64[0]);
    259             __put_user(avr->u64[PPC_VEC_LO], &vreg->u64[1]);
    260         }
    261 #if defined(TARGET_PPC64)
    262         vrsave = (uint32_t *)&frame->mc_vregs.altivec[33];
    263         /* 64-bit needs to put a pointer to the vectors in the frame */
    264         __put_user(h2g(frame->mc_vregs.altivec), &frame->v_regs);
    265 #else
    266         vrsave = (uint32_t *)&frame->mc_vregs.altivec[32];
    267 #endif
    268         __put_user((uint32_t)env->spr[SPR_VRSAVE], vrsave);
    269     }
    270 
    271 #if defined(TARGET_PPC64)
    272     /* Save VSX second halves */
    273     if (env->insns_flags2 & PPC2_VSX) {
    274         uint64_t *vsregs = (uint64_t *)&frame->mc_vregs.altivec[34];
    275         for (i = 0; i < 32; i++) {
    276             uint64_t *vsrl = cpu_vsrl_ptr(env, i);
    277             __put_user(*vsrl, &vsregs[i]);
    278         }
    279     }
    280 #endif
    281 
    282     /* Save floating point registers.  */
    283     if (env->insns_flags & PPC_FLOAT) {
    284         for (i = 0; i < 32; i++) {
    285             uint64_t *fpr = cpu_fpr_ptr(env, i);
    286             __put_user(*fpr, &frame->mc_fregs[i]);
    287         }
    288         __put_user((uint64_t) env->fpscr, &frame->mc_fregs[32]);
    289     }
    290 
    291 #if !defined(TARGET_PPC64)
    292     /* Save SPE registers.  The kernel only saves the high half.  */
    293     if (env->insns_flags & PPC_SPE) {
    294         for (i = 0; i < ARRAY_SIZE(env->gprh); i++) {
    295             __put_user(env->gprh[i], &frame->mc_vregs.spe[i]);
    296         }
    297         __put_user(env->spe_fscr, &frame->mc_vregs.spe[32]);
    298     }
    299 #endif
    300 
    301     /* Store MSR.  */
    302     __put_user(msr, &frame->mc_gregs[TARGET_PT_MSR]);
    303 }
    304 
    305 static void encode_trampoline(int sigret, uint32_t *tramp)
    306 {
    307     /* Set up the sigreturn trampoline: li r0,sigret; sc.  */
    308     __put_user(0x38000000 | sigret, &tramp[0]);
    309     __put_user(0x44000002, &tramp[1]);
    310 }
    311 
    312 static void restore_user_regs(CPUPPCState *env,
    313                               struct target_mcontext *frame, int sig)
    314 {
    315     target_ulong save_r2 = 0;
    316     target_ulong msr;
    317     target_ulong xer;
    318     target_ulong ccr;
    319 
    320     int i;
    321 
    322     if (!sig) {
    323         save_r2 = env->gpr[2];
    324     }
    325 
    326     /* Restore general registers.  */
    327     for (i = 0; i < ARRAY_SIZE(env->gpr); i++) {
    328         __get_user(env->gpr[i], &frame->mc_gregs[i]);
    329     }
    330     __get_user(env->nip, &frame->mc_gregs[TARGET_PT_NIP]);
    331     __get_user(env->ctr, &frame->mc_gregs[TARGET_PT_CTR]);
    332     __get_user(env->lr, &frame->mc_gregs[TARGET_PT_LNK]);
    333 
    334     __get_user(xer, &frame->mc_gregs[TARGET_PT_XER]);
    335     cpu_write_xer(env, xer);
    336 
    337     __get_user(ccr, &frame->mc_gregs[TARGET_PT_CCR]);
    338     for (i = 0; i < ARRAY_SIZE(env->crf); i++) {
    339         env->crf[i] = (ccr >> (32 - ((i + 1) * 4))) & 0xf;
    340     }
    341 
    342     if (!sig) {
    343         env->gpr[2] = save_r2;
    344     }
    345     /* Restore MSR.  */
    346     __get_user(msr, &frame->mc_gregs[TARGET_PT_MSR]);
    347 
    348     /* If doing signal return, restore the previous little-endian mode.  */
    349     if (sig) {
    350         ppc_store_msr(env, ((env->msr & ~(1ull << MSR_LE)) |
    351                             (msr & (1ull << MSR_LE))));
    352     }
    353 
    354     /* Restore Altivec registers if necessary.  */
    355     if (env->insns_flags & PPC_ALTIVEC) {
    356         ppc_avr_t *v_regs;
    357         uint32_t *vrsave;
    358 #if defined(TARGET_PPC64)
    359         uint64_t v_addr;
    360         /* 64-bit needs to recover the pointer to the vectors from the frame */
    361         __get_user(v_addr, &frame->v_regs);
    362         v_regs = g2h(env_cpu(env), v_addr);
    363 #else
    364         v_regs = (ppc_avr_t *)frame->mc_vregs.altivec;
    365 #endif
    366         for (i = 0; i < 32; i++) {
    367             ppc_avr_t *avr = cpu_avr_ptr(env, i);
    368             ppc_avr_t *vreg = &v_regs[i];
    369 
    370             __get_user(avr->u64[PPC_VEC_HI], &vreg->u64[0]);
    371             __get_user(avr->u64[PPC_VEC_LO], &vreg->u64[1]);
    372         }
    373 #if defined(TARGET_PPC64)
    374         vrsave = (uint32_t *)&v_regs[33];
    375 #else
    376         vrsave = (uint32_t *)&v_regs[32];
    377 #endif
    378         __get_user(env->spr[SPR_VRSAVE], vrsave);
    379     }
    380 
    381 #if defined(TARGET_PPC64)
    382     /* Restore VSX second halves */
    383     if (env->insns_flags2 & PPC2_VSX) {
    384         uint64_t *vsregs = (uint64_t *)&frame->mc_vregs.altivec[34];
    385         for (i = 0; i < 32; i++) {
    386             uint64_t *vsrl = cpu_vsrl_ptr(env, i);
    387             __get_user(*vsrl, &vsregs[i]);
    388         }
    389     }
    390 #endif
    391 
    392     /* Restore floating point registers.  */
    393     if (env->insns_flags & PPC_FLOAT) {
    394         uint64_t fpscr;
    395         for (i = 0; i < 32; i++) {
    396             uint64_t *fpr = cpu_fpr_ptr(env, i);
    397             __get_user(*fpr, &frame->mc_fregs[i]);
    398         }
    399         __get_user(fpscr, &frame->mc_fregs[32]);
    400         env->fpscr = (uint32_t) fpscr;
    401     }
    402 
    403 #if !defined(TARGET_PPC64)
    404     /* Save SPE registers.  The kernel only saves the high half.  */
    405     if (env->insns_flags & PPC_SPE) {
    406         for (i = 0; i < ARRAY_SIZE(env->gprh); i++) {
    407             __get_user(env->gprh[i], &frame->mc_vregs.spe[i]);
    408         }
    409         __get_user(env->spe_fscr, &frame->mc_vregs.spe[32]);
    410     }
    411 #endif
    412 }
    413 
    414 #if !defined(TARGET_PPC64)
    415 void setup_frame(int sig, struct target_sigaction *ka,
    416                  target_sigset_t *set, CPUPPCState *env)
    417 {
    418     struct target_sigframe *frame;
    419     struct target_sigcontext *sc;
    420     target_ulong frame_addr, newsp;
    421     int err = 0;
    422 
    423     frame_addr = get_sigframe(ka, env, sizeof(*frame));
    424     trace_user_setup_frame(env, frame_addr);
    425     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 1))
    426         goto sigsegv;
    427     sc = &frame->sctx;
    428 
    429     __put_user(ka->_sa_handler, &sc->handler);
    430     __put_user(set->sig[0], &sc->oldmask);
    431     __put_user(set->sig[1], &sc->_unused[3]);
    432     __put_user(h2g(&frame->mctx), &sc->regs);
    433     __put_user(sig, &sc->signal);
    434 
    435     /* Save user regs.  */
    436     save_user_regs(env, &frame->mctx);
    437 
    438     env->lr = default_sigreturn;
    439 
    440     /* Turn off all fp exceptions.  */
    441     env->fpscr = 0;
    442 
    443     /* Create a stack frame for the caller of the handler.  */
    444     newsp = frame_addr - SIGNAL_FRAMESIZE;
    445     err |= put_user(env->gpr[1], newsp, target_ulong);
    446 
    447     if (err)
    448         goto sigsegv;
    449 
    450     /* Set up registers for signal handler.  */
    451     env->gpr[1] = newsp;
    452     env->gpr[3] = sig;
    453     env->gpr[4] = frame_addr + offsetof(struct target_sigframe, sctx);
    454 
    455     env->nip = (target_ulong) ka->_sa_handler;
    456 
    457     /* Signal handlers are entered in big-endian mode.  */
    458     ppc_store_msr(env, env->msr & ~(1ull << MSR_LE));
    459 
    460     unlock_user_struct(frame, frame_addr, 1);
    461     return;
    462 
    463 sigsegv:
    464     unlock_user_struct(frame, frame_addr, 1);
    465     force_sigsegv(sig);
    466 }
    467 #endif /* !defined(TARGET_PPC64) */
    468 
    469 void setup_rt_frame(int sig, struct target_sigaction *ka,
    470                     target_siginfo_t *info,
    471                     target_sigset_t *set, CPUPPCState *env)
    472 {
    473     struct target_rt_sigframe *rt_sf;
    474     struct target_mcontext *mctx = 0;
    475     target_ulong rt_sf_addr, newsp = 0;
    476     int i, err = 0;
    477 #if defined(TARGET_PPC64)
    478     struct target_sigcontext *sc = 0;
    479     struct image_info *image = ((TaskState *)thread_cpu->opaque)->info;
    480 #endif
    481 
    482     rt_sf_addr = get_sigframe(ka, env, sizeof(*rt_sf));
    483     if (!lock_user_struct(VERIFY_WRITE, rt_sf, rt_sf_addr, 1))
    484         goto sigsegv;
    485 
    486     tswap_siginfo(&rt_sf->info, info);
    487 
    488     __put_user(0, &rt_sf->uc.tuc_flags);
    489     __put_user(0, &rt_sf->uc.tuc_link);
    490     target_save_altstack(&rt_sf->uc.tuc_stack, env);
    491 #if !defined(TARGET_PPC64)
    492     __put_user(h2g (&rt_sf->uc.tuc_mcontext),
    493                &rt_sf->uc.tuc_regs);
    494 #endif
    495     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
    496         __put_user(set->sig[i], &rt_sf->uc.tuc_sigmask.sig[i]);
    497     }
    498 
    499 #if defined(TARGET_PPC64)
    500     mctx = &rt_sf->uc.tuc_sigcontext.mcontext;
    501 
    502     sc = &rt_sf->uc.tuc_sigcontext;
    503     __put_user(h2g(mctx), &sc->regs);
    504     __put_user(sig, &sc->signal);
    505 #else
    506     mctx = &rt_sf->uc.tuc_mcontext;
    507 #endif
    508 
    509     save_user_regs(env, mctx);
    510 
    511     env->lr = default_rt_sigreturn;
    512 
    513     /* Turn off all fp exceptions.  */
    514     env->fpscr = 0;
    515 
    516     /* Create a stack frame for the caller of the handler.  */
    517     newsp = rt_sf_addr - (SIGNAL_FRAMESIZE + 16);
    518     err |= put_user(env->gpr[1], newsp, target_ulong);
    519 
    520     if (err)
    521         goto sigsegv;
    522 
    523     /* Set up registers for signal handler.  */
    524     env->gpr[1] = newsp;
    525     env->gpr[3] = (target_ulong) sig;
    526     env->gpr[4] = (target_ulong) h2g(&rt_sf->info);
    527     env->gpr[5] = (target_ulong) h2g(&rt_sf->uc);
    528     env->gpr[6] = (target_ulong) h2g(rt_sf);
    529 
    530 #if defined(TARGET_PPC64)
    531     if (get_ppc64_abi(image) < 2) {
    532         /* ELFv1 PPC64 function pointers are pointers to OPD entries. */
    533         struct target_func_ptr *handler =
    534             (struct target_func_ptr *)g2h(env_cpu(env), ka->_sa_handler);
    535         env->nip = tswapl(handler->entry);
    536         env->gpr[2] = tswapl(handler->toc);
    537     } else {
    538         /* ELFv2 PPC64 function pointers are entry points. R12 must also be set. */
    539         env->gpr[12] = env->nip = ka->_sa_handler;
    540     }
    541 #else
    542     env->nip = (target_ulong) ka->_sa_handler;
    543 #endif
    544 
    545 #if TARGET_BIG_ENDIAN
    546     /* Signal handlers are entered in big-endian mode.  */
    547     ppc_store_msr(env, env->msr & ~(1ull << MSR_LE));
    548 #else
    549     /* Signal handlers are entered in little-endian mode.  */
    550     ppc_store_msr(env, env->msr | (1ull << MSR_LE));
    551 #endif
    552 
    553     unlock_user_struct(rt_sf, rt_sf_addr, 1);
    554     return;
    555 
    556 sigsegv:
    557     unlock_user_struct(rt_sf, rt_sf_addr, 1);
    558     force_sigsegv(sig);
    559 
    560 }
    561 
    562 #if !defined(TARGET_PPC64)
    563 long do_sigreturn(CPUPPCState *env)
    564 {
    565     struct target_sigcontext *sc = NULL;
    566     struct target_mcontext *sr = NULL;
    567     target_ulong sr_addr = 0, sc_addr;
    568     sigset_t blocked;
    569     target_sigset_t set;
    570 
    571     sc_addr = env->gpr[1] + SIGNAL_FRAMESIZE;
    572     if (!lock_user_struct(VERIFY_READ, sc, sc_addr, 1))
    573         goto sigsegv;
    574 
    575     __get_user(set.sig[0], &sc->oldmask);
    576     __get_user(set.sig[1], &sc->_unused[3]);
    577 
    578     target_to_host_sigset_internal(&blocked, &set);
    579     set_sigmask(&blocked);
    580 
    581     __get_user(sr_addr, &sc->regs);
    582     if (!lock_user_struct(VERIFY_READ, sr, sr_addr, 1))
    583         goto sigsegv;
    584     restore_user_regs(env, sr, 1);
    585 
    586     unlock_user_struct(sr, sr_addr, 1);
    587     unlock_user_struct(sc, sc_addr, 1);
    588     return -QEMU_ESIGRETURN;
    589 
    590 sigsegv:
    591     unlock_user_struct(sr, sr_addr, 1);
    592     unlock_user_struct(sc, sc_addr, 1);
    593     force_sig(TARGET_SIGSEGV);
    594     return -QEMU_ESIGRETURN;
    595 }
    596 #endif /* !defined(TARGET_PPC64) */
    597 
    598 /* See arch/powerpc/kernel/signal_32.c.  */
    599 static int do_setcontext(struct target_ucontext *ucp, CPUPPCState *env, int sig)
    600 {
    601     struct target_mcontext *mcp;
    602     target_ulong mcp_addr;
    603     sigset_t blocked;
    604     target_sigset_t set;
    605 
    606     if (copy_from_user(&set, h2g(ucp) + offsetof(struct target_ucontext, tuc_sigmask),
    607                        sizeof (set)))
    608         return 1;
    609 
    610 #if defined(TARGET_PPC64)
    611     mcp_addr = h2g(ucp) +
    612         offsetof(struct target_ucontext, tuc_sigcontext.mcontext);
    613 #else
    614     __get_user(mcp_addr, &ucp->tuc_regs);
    615 #endif
    616 
    617     if (!lock_user_struct(VERIFY_READ, mcp, mcp_addr, 1))
    618         return 1;
    619 
    620     target_to_host_sigset_internal(&blocked, &set);
    621     set_sigmask(&blocked);
    622     restore_user_regs(env, mcp, sig);
    623 
    624     unlock_user_struct(mcp, mcp_addr, 1);
    625     return 0;
    626 }
    627 
    628 long do_rt_sigreturn(CPUPPCState *env)
    629 {
    630     struct target_rt_sigframe *rt_sf = NULL;
    631     target_ulong rt_sf_addr;
    632 
    633     rt_sf_addr = env->gpr[1] + SIGNAL_FRAMESIZE + 16;
    634     if (!lock_user_struct(VERIFY_READ, rt_sf, rt_sf_addr, 1))
    635         goto sigsegv;
    636 
    637     if (do_setcontext(&rt_sf->uc, env, 1))
    638         goto sigsegv;
    639 
    640     target_restore_altstack(&rt_sf->uc.tuc_stack, env);
    641 
    642     unlock_user_struct(rt_sf, rt_sf_addr, 1);
    643     return -QEMU_ESIGRETURN;
    644 
    645 sigsegv:
    646     unlock_user_struct(rt_sf, rt_sf_addr, 1);
    647     force_sig(TARGET_SIGSEGV);
    648     return -QEMU_ESIGRETURN;
    649 }
    650 
    651 /* This syscall implements {get,set,swap}context for userland.  */
    652 abi_long do_swapcontext(CPUArchState *env, abi_ulong uold_ctx,
    653                         abi_ulong unew_ctx, abi_long ctx_size)
    654 {
    655     struct target_ucontext *uctx;
    656     struct target_mcontext *mctx;
    657 
    658     /* For ppc32, ctx_size is "reserved for future use".
    659      * For ppc64, we do not yet support the VSX extension.
    660      */
    661     if (ctx_size < sizeof(struct target_ucontext)) {
    662         return -TARGET_EINVAL;
    663     }
    664 
    665     if (uold_ctx) {
    666         TaskState *ts = (TaskState *)thread_cpu->opaque;
    667 
    668         if (!lock_user_struct(VERIFY_WRITE, uctx, uold_ctx, 1)) {
    669             return -TARGET_EFAULT;
    670         }
    671 
    672 #ifdef TARGET_PPC64
    673         mctx = &uctx->tuc_sigcontext.mcontext;
    674 #else
    675         /* ??? The kernel aligns the pointer down here into padding, but
    676          * in setup_rt_frame we don't.  Be self-compatible for now.
    677          */
    678         mctx = &uctx->tuc_mcontext;
    679         __put_user(h2g(mctx), &uctx->tuc_regs);
    680 #endif
    681 
    682         save_user_regs(env, mctx);
    683         host_to_target_sigset(&uctx->tuc_sigmask, &ts->signal_mask);
    684 
    685         unlock_user_struct(uctx, uold_ctx, 1);
    686     }
    687 
    688     if (unew_ctx) {
    689         int err;
    690 
    691         if (!lock_user_struct(VERIFY_READ, uctx, unew_ctx, 1)) {
    692             return -TARGET_EFAULT;
    693         }
    694         err = do_setcontext(uctx, env, 0);
    695         unlock_user_struct(uctx, unew_ctx, 1);
    696 
    697         if (err) {
    698             /* We cannot return to a partially updated context.  */
    699             force_sig(TARGET_SIGSEGV);
    700         }
    701         return -QEMU_ESIGRETURN;
    702     }
    703 
    704     return 0;
    705 }
    706 
    707 void setup_sigtramp(abi_ulong sigtramp_page)
    708 {
    709     uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 8, 0);
    710     assert(tramp != NULL);
    711 
    712 #ifdef TARGET_ARCH_HAS_SETUP_FRAME
    713     default_sigreturn = sigtramp_page;
    714     encode_trampoline(TARGET_NR_sigreturn, tramp + 0);
    715 #endif
    716 
    717     default_rt_sigreturn = sigtramp_page + 8;
    718     encode_trampoline(TARGET_NR_rt_sigreturn, tramp + 2);
    719 
    720     unlock_user(tramp, sigtramp_page, 2 * 8);
    721 }