On 6/17/24 11:57, Ajeet Singh wrote:
> From: Stacey Son <sson@FreeBSD.org>
>
> signal trampoline function initializes a sequence of instructions
> to handle signal returns and exits, and copies this code to the target offset.
>
> Signed-off-by: Stacey Son <sson@FreeBSD.org>
> Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
> ---
> bsd-user/aarch64/target_arch_sigtramp.h | 48 +++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
> create mode 100644 bsd-user/aarch64/target_arch_sigtramp.h
>
> diff --git a/bsd-user/aarch64/target_arch_sigtramp.h b/bsd-user/aarch64/target_arch_sigtramp.h
> new file mode 100644
> index 0000000000..8cdd33b621
> --- /dev/null
> +++ b/bsd-user/aarch64/target_arch_sigtramp.h
> @@ -0,0 +1,48 @@
> +/*
> + * ARM AArch64 sigcode for bsd-user
> + *
> + * Copyright (c) 2015 Stacey D. Son <sson at FreeBSD>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library 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
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef TARGET_ARCH_SIGTRAMP_H
> +#define TARGET_ARCH_SIGTRAMP_H
> +
> +/* Compare to ENTRY(sigcode) in arm64/arm64/locore.S */
> +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;
> +
> + uint32_t sigtramp_code[] = {
> + /* 1 */ 0x910003e0, /* mov x0, sp */
> + /* 2 */ 0x91000000 + (sigf_uc << 10), /* add x0, x0, #SIGF_UC */
> + /* 3 */ 0xd2800000 + (sys_sigreturn << 5) + 0x8, /* mov x8, #SYS_sigreturn */
> + /* 4 */ 0xd4000001, /* svc #0 */
> + /* 5 */ 0xd2800028 + (sys_exit << 5) + 0x8, /* mov x8, #SYS_exit */
> + /* 6 */ 0xd4000001, /* svc #0 */
> + /* 7 */ 0x17fffffc, /* b -4 */
> + /* 8 */ sys_sigreturn,
> + /* 9 */ sys_exit
> + };
> +
> + for (i = 0; i < 9; i++) {
> + tswap32s(&sigtramp_code[i]);
> + }
You can use const_le32() to initialize sigtramp_code[], at which point it can be static const.
I'll note that bsd-user/arm/ could be improved the same way. In addition, the g_assert in
arm/ can be QEMU_BUILD_BUG_ON instead, to be caught at compile-time.
r~