[PATCH v19 02/13] linux-user: Add LoongArch signal support

[Song Gao <gaosong@loongson.cn>]

Signed-off-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
---
 linux-user/loongarch64/signal.c        | 331 +++++++++++++++++++++++++
 linux-user/loongarch64/target_signal.h |  13 +
 2 files changed, 344 insertions(+)
 create mode 100644 linux-user/loongarch64/signal.c
 create mode 100644 linux-user/loongarch64/target_signal.h

diff --git a/linux-user/loongarch64/signal.c b/linux-user/loongarch64/signal.c
new file mode 100644
index 0000000000..be04066400
--- /dev/null
+++ b/linux-user/loongarch64/signal.c
@@ -0,0 +1,331 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * LoongArch emulation of Linux signals
+ *
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ */
+
+#include "qemu/osdep.h"
+#include "qemu.h"
+#include "user-internals.h"
+#include "signal-common.h"
+#include "linux-user/trace.h"
+
+#include "target/loongarch/internals.h"
+
+/* FP context was used */
+#define SC_USED_FP              (1 << 0)
+
+struct target_sigcontext {
+    uint64_t sc_pc;
+    uint64_t sc_regs[32];
+    uint32_t sc_flags;
+    uint64_t sc_extcontext[0]   QEMU_ALIGNED(16);
+};
+
+
+#define FPU_CTX_MAGIC           0x46505501
+#define FPU_CTX_ALIGN           8
+struct target_fpu_context {
+    uint64_t regs[32];
+    uint64_t fcc;
+    uint32_t fcsr;
+};
+
+#define CONTEXT_INFO_ALIGN      16
+struct sctx_info {
+    uint32_t magic;
+    uint32_t size;
+    uint64_t padding;           /* padding to 16 bytes */
+};
+
+struct target_ucontext {
+    target_ulong tuc_flags;
+    struct target_ucontext *tuc_link;
+    target_stack_t tuc_stack;
+    target_sigset_t tuc_sigmask;
+    uint8_t __unused[1024 / 8 - sizeof(target_sigset_t)];
+    struct target_sigcontext tuc_mcontext;
+};
+
+struct target_rt_sigframe {
+    struct target_siginfo        rs_info;
+    struct target_ucontext       rs_uc;
+    struct sctx_info             rs_fpu_info QEMU_ALIGNED(16);
+    struct target_fpu_context    rs_fpu;
+    struct sctx_info             rs_end_info QEMU_ALIGNED(16);
+};
+
+struct ctx_layout {
+    abi_ulong addr;
+    unsigned int size;
+};
+
+struct extctx_layout {
+    unsigned int size;
+    unsigned int flags;
+    struct ctx_layout fpu;
+    struct ctx_layout end;
+};
+
+static uint64_t read_all_fcc(CPULoongArchState *env)
+{
+    uint64_t ret = 0;
+
+    for (int i = 0; i < 8; ++i) {
+        ret |= (uint64_t)env->cf[i] << (i * 8);
+    }
+
+    return ret;
+}
+
+static void write_all_fcc(CPULoongArchState *env, uint64_t val)
+{
+    for (int i = 0; i < 8; ++i) {
+        env->cf[i] = (val >> (i * 8)) & 1;
+    }
+}
+
+static void copy_fpu_to_sigframe(CPULoongArchState *env,
+                                 struct target_rt_sigframe *frame,
+                                 struct extctx_layout *extctx)
+{
+    int i;
+    struct target_fpu_context *fpu_ctx = &frame->rs_fpu;
+
+    for (i = 0; i < 32; ++i) {
+        __put_user(env->fpr[i], &fpu_ctx->regs[i]);
+    }
+
+    fpu_ctx->fcc = read_all_fcc(env);
+    __put_user(env->fcsr0, &fpu_ctx->fcsr);
+
+    /* Set fpu_context info */
+    __put_user(FPU_CTX_MAGIC, &frame->rs_fpu_info.magic);
+    __put_user(extctx->fpu.size, &frame->rs_fpu_info.size);
+}
+
+static void setup_extcontext(struct extctx_layout *extctx, abi_ulong sp)
+{
+    memset(extctx, 0, sizeof(struct extctx_layout));
+
+    extctx->end.addr = sp + offsetof(struct target_rt_sigframe, rs_end_info);
+    extctx->end.size = sizeof(struct sctx_info);
+    extctx->fpu.addr = sp + offsetof(struct target_rt_sigframe, rs_fpu_info);
+    extctx->fpu.size = extctx->end.addr - extctx->fpu.addr;
+    extctx->size = extctx->fpu.size + extctx->end.size;
+    extctx->flags = SC_USED_FP;
+}
+
+static void setup_sigcontext(CPULoongArchState *env,
+                             struct target_sigcontext *sc,
+                             struct extctx_layout *extctx)
+{
+    int i;
+
+    if (extctx->flags & SC_USED_FP) {
+        __put_user(extctx->fpu.addr, &sc->sc_extcontext[0]);
+    } else {
+        __put_user(extctx->end.addr, &sc->sc_extcontext[0]);
+    }
+    __put_user(extctx->flags, &sc->sc_flags);
+    __put_user(env->pc, &sc->sc_pc);
+
+    for (i = 1; i < 32; ++i) {
+        __put_user(env->gpr[i], &sc->sc_regs[i]);
+    }
+}
+
+static void copy_fpu_from_sigframe(CPULoongArchState *env,
+                                   struct target_rt_sigframe *frame)
+{
+    int i;
+    struct target_fpu_context *fpu_ctx = &frame->rs_fpu;
+
+    for (i = 1; i < 32; ++i) {
+        __get_user(env->fpr[i], &fpu_ctx->regs[i]);
+    }
+    write_all_fcc(env, fpu_ctx->fcc);
+    __get_user(env->fcsr0, &fpu_ctx->fcsr);
+}
+
+static void setup_sigframe(CPULoongArchState *env,
+                           struct target_rt_sigframe *frame,
+                           struct extctx_layout *extctx)
+{
+    setup_sigcontext(env, &frame->rs_uc.tuc_mcontext, extctx);
+
+    /* Set fpu_context */
+    if (extctx->flags & SC_USED_FP) {
+        copy_fpu_to_sigframe(env, frame, extctx);
+    }
+
+    /* Set end context */
+    __put_user(0, &frame->rs_end_info.magic);
+    __put_user(extctx->end.size, &frame->rs_end_info.size);
+}
+
+static int parse_extcontext(struct target_sigcontext *sc,
+                            struct extctx_layout *extctx)
+{
+    unsigned int magic, size;
+    struct sctx_info *info = (struct sctx_info *)&sc->sc_extcontext;
+
+    while (1) {
+        __get_user(magic, &info->magic);
+        __get_user(size, &info->size);
+
+        switch (magic) {
+        case 0: /* END */
+            goto done;
+        case FPU_CTX_MAGIC:
+            if (size < (sizeof(struct sctx_info) +
+                        sizeof(struct target_fpu_context))) {
+                goto invalid;
+            }
+            extctx->fpu.addr = (abi_ulong)info;
+            break;
+        default:
+            goto invalid;
+        }
+        info = (struct sctx_info *)((char *)info + size);
+    }
+
+done:
+    return 0;
+invalid:
+    return -TARGET_EINVAL;
+}
+
+static int restore_sigframe(CPULoongArchState *env,
+                            struct target_rt_sigframe *frame)
+{
+    int i;
+    int ret = 0;
+    struct extctx_layout extctx;
+    struct target_sigcontext *sc = &frame->rs_uc.tuc_mcontext;
+
+    memset(&extctx, 0, sizeof(struct extctx_layout));
+
+    __get_user(extctx.flags, &sc->sc_flags);
+
+    ret = parse_extcontext(sc, &extctx);
+    if (ret < 0) {
+        goto bad;
+    }
+
+    __get_user(env->pc, &sc->sc_pc);
+    for (i = 1; i < 32; ++i) {
+        __get_user(env->gpr[i], &sc->sc_regs[i]);
+    }
+
+    if (extctx.fpu.addr) {
+        copy_fpu_from_sigframe(env, frame);
+        restore_fp_status(env);
+    }
+bad:
+    return ret;
+}
+
+/*
+ * Determine which stack to use.
+ */
+static abi_ulong get_sigframe(struct target_sigaction *ka,
+                              CPULoongArchState *env, size_t frame_size,
+                              struct extctx_layout *extctx)
+{
+    abi_ulong sp;
+
+    sp = target_sigsp(get_sp_from_cpustate(env) - 32, ka);
+    sp = (sp - frame_size) & ~15UL;
+
+    return sp;
+}
+
+void setup_rt_frame(int sig, struct target_sigaction *ka,
+                    target_siginfo_t *info,
+                    target_sigset_t *set, CPULoongArchState *env)
+{
+    struct target_rt_sigframe *frame;
+    struct extctx_layout extctx;
+    abi_ulong frame_addr;
+    int i;
+
+    frame_addr = get_sigframe(ka, env, sizeof(*frame), &extctx);
+    trace_user_setup_rt_frame(env, frame_addr);
+    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
+        goto give_sigsegv;
+    }
+
+    setup_extcontext(&extctx, frame_addr);
+
+    tswap_siginfo(&frame->rs_info, info);
+
+    __put_user(0, &frame->rs_uc.tuc_flags);
+    __put_user(0, &frame->rs_uc.tuc_link);
+    target_save_altstack(&frame->rs_uc.tuc_stack, env);
+
+    setup_sigframe(env, frame, &extctx);
+
+    for (i = 0; i < TARGET_NSIG_WORDS; i++) {
+        __put_user(set->sig[i], &frame->rs_uc.tuc_sigmask.sig[i]);
+    }
+
+    env->gpr[4] = sig;
+    env->gpr[5] = frame_addr + offsetof(struct target_rt_sigframe, rs_info);
+    env->gpr[6] = frame_addr + offsetof(struct target_rt_sigframe, rs_uc);
+    env->gpr[3] = frame_addr;
+    env->gpr[1] = default_rt_sigreturn;
+
+    env->pc = ka->_sa_handler;
+    unlock_user_struct(frame, frame_addr, 1);
+    return;
+
+give_sigsegv:
+    unlock_user_struct(frame, frame_addr, 1);
+    force_sigsegv(sig);
+}
+
+long do_rt_sigreturn(CPULoongArchState *env)
+{
+    int ret = 0;
+    struct target_rt_sigframe *frame;
+    abi_ulong frame_addr;
+    sigset_t blocked;
+
+    frame_addr = env->gpr[3];
+    trace_user_do_rt_sigreturn(env, frame_addr);
+    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
+        goto badframe;
+    }
+
+    target_to_host_sigset(&blocked, &frame->rs_uc.tuc_sigmask);
+    set_sigmask(&blocked);
+
+    ret = restore_sigframe(env, frame);
+    if (ret < 0) {
+        goto badframe;
+    }
+
+    target_restore_altstack(&frame->rs_uc.tuc_stack, env);
+
+    unlock_user_struct(frame, frame_addr, 0);
+    return -QEMU_ESIGRETURN;
+
+badframe:
+    unlock_user_struct(frame, frame_addr, 0);
+    force_sig(TARGET_SIGSEGV);
+    return -QEMU_ESIGRETURN;
+}
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0);
+    assert(tramp != NULL);
+
+    __put_user(0x03822c0b, tramp + 0);  /* ori     a7, zero, 0x8b */
+    __put_user(0x002b0000, tramp + 1);  /* syscall 0 */
+
+    default_rt_sigreturn = sigtramp_page;
+    unlock_user(tramp, sigtramp_page, 8);
+}
diff --git a/linux-user/loongarch64/target_signal.h b/linux-user/loongarch64/target_signal.h
new file mode 100644
index 0000000000..ad3aaffcb4
--- /dev/null
+++ b/linux-user/loongarch64/target_signal.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ */
+
+#ifndef LOONGARCH_TARGET_SIGNAL_H
+#define LOONGARCH_TARGET_SIGNAL_H
+
+#include "../generic/signal.h"
+
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
+#endif /* LOONGARCH_TARGET_SIGNAL_H */
-- 
2.31.1