Re: [PATCH 12/24] bsd-user/arm/target_arch_sigtramp.h: Signal Trampoline for arm

[Kyle Evans]

On Tue, Oct 19, 2021 at 11:45 AM Warner Losh <imp@bsdimp.com> wrote:
>
> Copy of the signal trampoline code for arm, as well as setup_sigtramp to
> write it to the stack.
>
> Signed-off-by: Stacey Son <sson@FreeBSD.org>
> Signed-off-by: Warner Losh <imp@bsdimp.com>
> ---
>  bsd-user/arm/target_arch_sigtramp.h | 52 +++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
>  create mode 100644 bsd-user/arm/target_arch_sigtramp.h
>
> diff --git a/bsd-user/arm/target_arch_sigtramp.h 
> b/bsd-user/arm/target_arch_sigtramp.h
> new file mode 100644
> index 0000000000..ed53d336ed
> --- /dev/null
> +++ b/bsd-user/arm/target_arch_sigtramp.h
> @@ -0,0 +1,52 @@
> +/*
> + *  arm sysarch() system call emulation
> + *
> + *  Copyright (c) 2013 Stacey D. Son
> + *
> + *  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/>.
> + */
> +
> +#ifndef _TARGET_ARCH_SIGTRAMP_H_
> +#define _TARGET_ARCH_SIGTRAMP_H_
> +
> +/* Compare to arm/arm/locore.S ENTRY_NP(sigcode) */
> +static inline abi_long setup_sigtramp(abi_ulong offset, unsigned sigf_uc,
> +        unsigned sys_sigreturn)
> +{
> +    int i;
> +    uint32_t sys_exit = TARGET_FREEBSD_NR_exit;
> +    /*
> +     * The code has to load r7 manually rather than using
> +     * "ldr r7, =SYS_return to make sure the size of the
> +     * code is correct.
> +     */
> +    uint32_t sigtramp_code[] = {
> +    /* 1 */ 0xE1A0000D,                  /* mov r0, sp */
> +    /* 2 */ 0xE2800000 + sigf_uc,        /* add r0, r0, #SIGF_UC */
> +    /* 3 */ 0xE59F700C,                  /* ldr r7, [pc, #12] */
> +    /* 4 */ 0xEF000000 + sys_sigreturn,  /* swi (SYS_sigreturn) */
> +    /* 5 */ 0xE59F7008,                  /* ldr r7, [pc, #8] */
> +    /* 6 */ 0xEF000000 + sys_exit,       /* swi (SYS_exit)*/
> +    /* 7 */ 0xEAFFFFFA,                  /* b . -16 */
> +    /* 8 */ sys_sigreturn,
> +    /* 9 */ sys_exit
> +    };
> +
> +    for (i = 0; i < 9; i++) {
> +        tswap32s(&sigtramp_code[i]);
> +    }
> +
> +    return memcpy_to_target(offset, sigtramp_code, TARGET_SZSIGCODE);
> +}
> +#endif /* _TARGET_ARCH_SIGTRAMP_H_ */
> --
> 2.32.0
>

Reviewed-by: Kyle Evans <kevans@FreeBSD.org>