linux-user: Add signal handling for AArch64

This patch adds signal handling for AArch64. The code is based on the
respective source in the Linux kernel.
Signed-off-by: NAndreas Schwab <schwab@suse.de>
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NJohn Rigby <john.rigby@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1378235544-22290-17-git-send-email-peter.maydell@linaro.org
Message-id: 1368505980-17151-10-git-send-email-john.rigby@linaro.org
[PMM: fixed style nits: tabs, long lines;
 pulled target_signal.h in from a later patch; it fits better here]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

linux-user/aarch64/target_signal.h

+#ifndef TARGET_SIGNAL_H
+#define TARGET_SIGNAL_H
+
+#include "cpu.h"
+
+/* this struct defines a stack used during syscall handling */
+
+typedef struct target_sigaltstack {
+    abi_ulong ss_sp;
+    abi_int ss_flags;
+    abi_ulong ss_size;
+} target_stack_t;
+
+
+/*
+ * sigaltstack controls
+ */
+#define TARGET_SS_ONSTACK 1
+#define TARGET_SS_DISABLE 2
+
+#define TARGET_MINSIGSTKSZ 2048
+#define TARGET_SIGSTKSZ 8192
+
+static inline abi_ulong get_sp_from_cpustate(CPUARMState *state)
+{
+   return state->xregs[31];
+}
+
+#endif /* TARGET_SIGNAL_H */

linux-user/signal.c

@@ -1092,6 +1092,266 @@ badframe:
 	return 0;
 }
 
+#elif defined(TARGET_AARCH64)
+
+struct target_sigcontext {
+    uint64_t fault_address;
+    /* AArch64 registers */
+    uint64_t regs[31];
+    uint64_t sp;
+    uint64_t pc;
+    uint64_t pstate;
+    /* 4K reserved for FP/SIMD state and future expansion */
+    char __reserved[4096] __attribute__((__aligned__(16)));
+};
+
+struct target_ucontext {
+    abi_ulong tuc_flags;
+    abi_ulong tuc_link;
+    target_stack_t tuc_stack;
+    target_sigset_t tuc_sigmask;
+    /* glibc uses a 1024-bit sigset_t */
+    char __unused[1024 / 8 - sizeof(target_sigset_t)];
+    /* last for future expansion */
+    struct target_sigcontext tuc_mcontext;
+};
+
+/*
+ * Header to be used at the beginning of structures extending the user
+ * context. Such structures must be placed after the rt_sigframe on the stack
+ * and be 16-byte aligned. The last structure must be a dummy one with the
+ * magic and size set to 0.
+ */
+struct target_aarch64_ctx {
+    uint32_t magic;
+    uint32_t size;
+};
+
+#define TARGET_FPSIMD_MAGIC 0x46508001
+
+struct target_fpsimd_context {
+    struct target_aarch64_ctx head;
+    uint32_t fpsr;
+    uint32_t fpcr;
+    uint64_t vregs[32 * 2]; /* really uint128_t vregs[32] */
+};
+
+/*
+ * Auxiliary context saved in the sigcontext.__reserved array. Not exported to
+ * user space as it will change with the addition of new context. User space
+ * should check the magic/size information.
+ */
+struct target_aux_context {
+    struct target_fpsimd_context fpsimd;
+    /* additional context to be added before "end" */
+    struct target_aarch64_ctx end;
+};
+
+struct target_rt_sigframe {
+    struct target_siginfo info;
+    struct target_ucontext uc;
+    uint64_t fp;
+    uint64_t lr;
+    uint32_t tramp[2];
+};
+
+static int target_setup_sigframe(struct target_rt_sigframe *sf,
+                                 CPUARMState *env, target_sigset_t *set)
+{
+    int i;
+    struct target_aux_context *aux =
+        (struct target_aux_context *)sf->uc.tuc_mcontext.__reserved;
+
+    /* set up the stack frame for unwinding */
+    __put_user(env->xregs[29], &sf->fp);
+    __put_user(env->xregs[30], &sf->lr);
+
+    for (i = 0; i < 31; i++) {
+        __put_user(env->xregs[i], &sf->uc.tuc_mcontext.regs[i]);
+    }
+    __put_user(env->xregs[31], &sf->uc.tuc_mcontext.sp);
+    __put_user(env->pc, &sf->uc.tuc_mcontext.pc);
+    __put_user(env->pstate, &sf->uc.tuc_mcontext.pstate);
+
+    __put_user(/*current->thread.fault_address*/ 0,
+            &sf->uc.tuc_mcontext.fault_address);
+
+    for (i = 0; i < TARGET_NSIG_WORDS; i++) {
+        __put_user(set->sig[i], &sf->uc.tuc_sigmask.sig[i]);
+    }
+
+    for (i = 0; i < 32; i++) {
+#ifdef TARGET_WORDS_BIGENDIAN
+        __put_user(env->vfp.regs[i * 2], &aux->fpsimd.vregs[i * 2 + 1]);
+        __put_user(env->vfp.regs[i * 2 + 1], &aux->fpsimd.vregs[i * 2]);
+#else
+        __put_user(env->vfp.regs[i * 2], &aux->fpsimd.vregs[i * 2]);
+        __put_user(env->vfp.regs[i * 2 + 1], &aux->fpsimd.vregs[i * 2 + 1]);
+#endif
+    }
+    __put_user(/*env->fpsr*/0, &aux->fpsimd.fpsr);
+    __put_user(/*env->fpcr*/0, &aux->fpsimd.fpcr);
+    __put_user(TARGET_FPSIMD_MAGIC, &aux->fpsimd.head.magic);
+    __put_user(sizeof(struct target_fpsimd_context),
+            &aux->fpsimd.head.size);
+
+    /* set the "end" magic */
+    __put_user(0, &aux->end.magic);
+    __put_user(0, &aux->end.size);
+
+    return 0;
+}
+
+static int target_restore_sigframe(CPUARMState *env,
+                                   struct target_rt_sigframe *sf)
+{
+    sigset_t set;
+    int i;
+    struct target_aux_context *aux =
+        (struct target_aux_context *)sf->uc.tuc_mcontext.__reserved;
+    uint32_t magic, size;
+
+    target_to_host_sigset(&set, &sf->uc.tuc_sigmask);
+    sigprocmask(SIG_SETMASK, &set, NULL);
+
+    for (i = 0; i < 31; i++) {
+        __get_user(env->xregs[i], &sf->uc.tuc_mcontext.regs[i]);
+    }
+
+    __get_user(env->xregs[31], &sf->uc.tuc_mcontext.sp);
+    __get_user(env->pc, &sf->uc.tuc_mcontext.pc);
+    __get_user(env->pstate, &sf->uc.tuc_mcontext.pstate);
+
+    __get_user(magic, &aux->fpsimd.head.magic);
+    __get_user(size, &aux->fpsimd.head.size);
+
+    if (magic != TARGET_FPSIMD_MAGIC
+        || size != sizeof(struct target_fpsimd_context)) {
+        return 1;
+    }
+
+    for (i = 0; i < 32 * 2; i++) {
+        __get_user(env->vfp.regs[i], &aux->fpsimd.vregs[i]);
+    }
+
+    return 0;
+}
+
+static abi_ulong get_sigframe(struct target_sigaction *ka, CPUARMState *env)
+{
+    abi_ulong sp;
+
+    sp = env->xregs[31];
+
+    /*
+     * This is the X/Open sanctioned signal stack switching.
+     */
+    if ((ka->sa_flags & SA_ONSTACK) && !sas_ss_flags(sp)) {
+        sp = target_sigaltstack_used.ss_sp + target_sigaltstack_used.ss_size;
+    }
+
+    sp = (sp - sizeof(struct target_rt_sigframe)) & ~15;
+
+    return sp;
+}
+
+static void target_setup_frame(int usig, struct target_sigaction *ka,
+                               target_siginfo_t *info, target_sigset_t *set,
+                               CPUARMState *env)
+{
+    struct target_rt_sigframe *frame;
+    abi_ulong frame_addr;
+
+    frame_addr = get_sigframe(ka, env);
+    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
+        goto give_sigsegv;
+    }
+
+    __put_user(0, &frame->uc.tuc_flags);
+    __put_user(0, &frame->uc.tuc_link);
+
+    __put_user(target_sigaltstack_used.ss_sp,
+                      &frame->uc.tuc_stack.ss_sp);
+    __put_user(sas_ss_flags(env->xregs[31]),
+                      &frame->uc.tuc_stack.ss_flags);
+    __put_user(target_sigaltstack_used.ss_size,
+                      &frame->uc.tuc_stack.ss_size);
+    target_setup_sigframe(frame, env, set);
+    /* mov x8,#__NR_rt_sigreturn; svc #0 */
+    __put_user(0xd2801168, &frame->tramp[0]);
+    __put_user(0xd4000001, &frame->tramp[1]);
+    env->xregs[0] = usig;
+    env->xregs[31] = frame_addr;
+    env->xregs[29] = env->xregs[31] + offsetof(struct target_rt_sigframe, fp);
+    env->pc = ka->_sa_handler;
+    env->xregs[30] = env->xregs[31] +
+        offsetof(struct target_rt_sigframe, tramp);
+    if (info) {
+        if (copy_siginfo_to_user(&frame->info, info)) {
+            goto give_sigsegv;
+        }
+        env->xregs[1] = frame_addr + offsetof(struct target_rt_sigframe, info);
+        env->xregs[2] = frame_addr + offsetof(struct target_rt_sigframe, uc);
+    }
+
+    unlock_user_struct(frame, frame_addr, 1);
+    return;
+
+ give_sigsegv:
+    unlock_user_struct(frame, frame_addr, 1);
+    force_sig(TARGET_SIGSEGV);
+}
+
+static void setup_rt_frame(int sig, struct target_sigaction *ka,
+                           target_siginfo_t *info, target_sigset_t *set,
+                           CPUARMState *env)
+{
+    target_setup_frame(sig, ka, info, set, env);
+}
+
+static void setup_frame(int sig, struct target_sigaction *ka,
+                        target_sigset_t *set, CPUARMState *env)
+{
+    target_setup_frame(sig, ka, 0, set, env);
+}
+
+long do_rt_sigreturn(CPUARMState *env)
+{
+    struct target_rt_sigframe *frame;
+    abi_ulong frame_addr = env->xregs[31];
+
+    if (frame_addr & 15) {
+        goto badframe;
+    }
+
+    if  (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
+        goto badframe;
+    }
+
+    if (target_restore_sigframe(env, frame)) {
+        goto badframe;
+    }
+
+    if (do_sigaltstack(frame_addr +
+            offsetof(struct target_rt_sigframe, uc.tuc_stack),
+            0, get_sp_from_cpustate(env)) == -EFAULT) {
+        goto badframe;
+    }
+
+    unlock_user_struct(frame, frame_addr, 0);
+    return env->xregs[0];
+
+ badframe:
+    unlock_user_struct(frame, frame_addr, 0);
+    force_sig(TARGET_SIGSEGV);
+    return 0;
+}
+
+long do_sigreturn(CPUARMState *env)
+{
+    return do_rt_sigreturn(env);
+}
+
 #elif defined(TARGET_ARM)
 
 struct target_sigcontext {