Re: [PATCH 15/18] bsd-user: Implement RISC-V signal trampoline setup functions

[Richard Henderson <richard.henderson@linaro.org>]

On 8/2/24 18:34, Ajeet Singh wrote:
> From: Mark Corbin <mark.corbin@embecsom.com>
> 
> Added functions for setting up the RISC-V signal trampoline and signal
> frame:
> 
> 'set_sigtramp_args()': Configures the RISC-V CPU state with arguments
> for the signal handler. It sets up the registers with the signal
> number,pointers to the signal info and user context, the signal handler
> address, and the signal frame pointer.
> 
> 'setup_sigframe_arch()': Initializes the signal frame with the current
> machine context.This function copies the context from the CPU state to
> the signal frame, preparing it for the signal handler.
> 
> Signed-off-by: Mark Corbin <mark.corbin@embecsom.com>
> Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
> Signed-off-by: Warner Losh <imp@bsdimp.com>
> Co-authored-by: Warner Losh <imp@bsdimp.com>
> ---
>   bsd-user/riscv/signal.c | 63 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 63 insertions(+)
>   create mode 100644 bsd-user/riscv/signal.c
> 
> diff --git a/bsd-user/riscv/signal.c b/bsd-user/riscv/signal.c
> new file mode 100644
> index 0000000000..005eb53cab
> --- /dev/null
> +++ b/bsd-user/riscv/signal.c
> @@ -0,0 +1,63 @@
> +/*
> + *  RISC-V signal definitions
> + *
> + *  Copyright (c) 2019 Mark Corbin
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +#include "qemu/osdep.h"
> +
> +#include "qemu.h"
> +
> +/*
> + * Compare with sendsig() in riscv/riscv/exec_machdep.c
> + * Assumes that target stack frame memory is locked.
> + */
> +abi_long
> +set_sigtramp_args(CPURISCVState *regs, int sig, struct target_sigframe *frame,
> +    abi_ulong frame_addr, struct target_sigaction *ka)
> +{
> +    /*
> +     * Arguments to signal handler:
> +     *  a0 (10) = signal number
> +     *  a1 (11) = siginfo pointer
> +     *  a2 (12) = ucontext pointer
> +     *  pc      = signal pointer handler
> +     *  sp (2)  = sigframe pointer
> +     *  ra (1)  = sigtramp at base of user stack
> +     */
> +
> +     regs->gpr[10] = sig;
> +     regs->gpr[11] = frame_addr +
> +         offsetof(struct target_sigframe, sf_si);
> +     regs->gpr[12] = frame_addr +
> +         offsetof(struct target_sigframe, sf_uc);

xA0 .. xA2

> +     regs->pc = ka->_sa_handler;
> +     regs->gpr[2] = frame_addr;
> +     regs->gpr[1] = TARGET_PS_STRINGS - TARGET_SZSIGCODE;

xRA, xSP.

Otherwise,
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~