[v14,19/26] linux-user: Add LoongArch signal support

Signed-off-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
---
 linux-user/loongarch64/signal.c        | 198 +++++++++++++++++++++++++
 linux-user/loongarch64/target_signal.h |  13 ++
 2 files changed, 211 insertions(+)
 create mode 100644 linux-user/loongarch64/signal.c
 create mode 100644 linux-user/loongarch64/target_signal.h

On 1/6/22 1:41 AM, Song Gao wrote:
> +struct target_sigcontext {
> +    uint64_t sc_pc;
> +    uint64_t sc_regs[32];
> +    uint32_t sc_flags;
> +    uint32_t sc_fcsr;
> +    uint32_t sc_vcsr;
> +    uint64_t sc_fcc;
> +    uint64_t sc_scr[4];
> +    union fpureg sc_fpregs[32] __attribute__((aligned(32)));
> +    uint8_t sc_reserved[4096] __attribute__((aligned(16)));
> +};

Does not match the current (December 31) kernel source.

> +static inline void setup_sigcontext(CPULoongArchState *env,
> +                                    struct target_sigcontext *sc)

Don't bother with inline markers anywhere in this file.  Let the compiler decide.

> +restore_sigcontext(CPULoongArchState *env, struct target_sigcontext *sc)
> +{
> +    int i;
> +
> +    __get_user(env->pc, &sc->sc_pc);
> +    __get_user(env->fcsr0, &sc->sc_fcsr);

You need to call restore_fp_status after this assignment, somewhere before the end of the 
function.

Otherwise this looks ok.


r~

On 1/6/22 17:41, Song Gao wrote:
> Signed-off-by: Song Gao<gaosong@loongson.cn>
> Signed-off-by: Xiaojuan Yang<yangxiaojuan@loongson.cn>
> ---
>   linux-user/loongarch64/signal.c        | 198 +++++++++++++++++++++++++
>   linux-user/loongarch64/target_signal.h |  13 ++
>   2 files changed, 211 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..9f0e6421b2
> --- /dev/null
> +++ b/linux-user/loongarch64/signal.c
> @@ -0,0 +1,198 @@
> +/* 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 "signal-common.h"
> +#include "user-internals.h"
> +#include "linux-user/trace.h"
> +
> +#define FPU_REG_WIDTH 256
> +union fpureg {
> +    uint32_t val32[FPU_REG_WIDTH / 32];
> +    uint64_t val64[FPU_REG_WIDTH / 64];
> +};
This is code preemptively added to support the LASX extensions? I 
remember the LASX extension in 3A4000/MIPS era uses 256-bit vector 
registers just like this.
> +
> +struct target_sigcontext {
> +    uint64_t sc_pc;
> +    uint64_t sc_regs[32];
> +    uint32_t sc_flags;
> +    uint32_t sc_fcsr;
> +    uint32_t sc_vcsr;
> +    uint64_t sc_fcc;
> +    uint64_t sc_scr[4];
> +    union fpureg sc_fpregs[32] __attribute__((aligned(32)));
> +    uint8_t sc_reserved[4096] __attribute__((aligned(16)));
> +};
As Richard pointed out, you need to have this synchronized to the 
kernel's definition. It's okay to update after SIMD support lands there, 
it's not to be considered code churn.
> +
> +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;
> +};
> +
> +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 inline void setup_sigcontext(CPULoongArchState *env,
> +                                    struct target_sigcontext *sc)
> +{
> +    int i;
> +
> +    __put_user(env->pc, &sc->sc_pc);
> +    __put_user(0, &sc->sc_regs[0]);
> +    __put_user(env->fcsr0, &sc->sc_fcsr);
> +    __put_user(0, &sc->sc_vcsr);
> +    sc->sc_fcc = read_all_fcc(env);
> +
> +    for (i = 0; i < 4; ++i) {
> +        __put_user(0, &sc->sc_scr[i]);
> +    }
> +
> +    for (i = 1; i < 32; ++i) {
> +        __put_user(env->gpr[i], &sc->sc_regs[i]);
> +    }
> +
> +    for (i = 0; i < 32; ++i) {
> +        __put_user(env->fpr[i], &sc->sc_fpregs[i].val64[0]);
> +    }
> +}
> +
> +static inline void
> +restore_sigcontext(CPULoongArchState *env, struct target_sigcontext *sc)
> +{
> +    int i;
> +
> +    __get_user(env->pc, &sc->sc_pc);
> +    __get_user(env->fcsr0, &sc->sc_fcsr);
> +    write_all_fcc(env, sc->sc_fcc);
> +
> +    for (i = 1; i < 32; ++i) {
> +        __get_user(env->gpr[i], &sc->sc_regs[i]);
> +    }
> +
> +    for (i = 0; i < 32; ++i) {
> +        __get_user(env->fpr[i], &sc->sc_fpregs[i].val64[0]);
> +    }
> +}
> +
> +/*
> + * Determine which stack to use..
Duplicate period (".").
> + */
> +static inline abi_ulong
> +get_sigframe(struct target_sigaction *ka, CPULoongArchState *env,
> +             size_t frame_size)
> +{
> +    unsigned long sp;
> +
> +    sp = target_sigsp(get_sp_from_cpustate(env) - 32, ka);
> +
> +    return (sp - frame_size) & ~15;
> +}
> +
> +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;
> +    abi_ulong frame_addr;
> +    int i;
> +
> +    frame_addr = get_sigframe(ka, env, sizeof(*frame));
> +    trace_user_setup_rt_frame(env, frame_addr);
> +    if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
> +        goto give_sigsegv;
> +    }
> +
> +    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_sigcontext(env, &frame->rs_uc.tuc_mcontext);
> +
> +    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)
> +{
> +    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);
> +
> +    restore_sigcontext(env, &frame->rs_uc.tuc_mcontext);
> +    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 */