[PATCH 20/23] ARM: signal: sigreturn_codes should be endian neutral to work in BE8
Uwe Kleine-König
u.kleine-koenig at pengutronix.de
Tue Nov 5 16:18:07 EST 2013
Hello,
On Wed, Oct 09, 2013 at 12:34:36AM +0200, Ben Dooks wrote:
> From: Victor Kamensky <victor.kamensky at linaro.org>
>
> In case of BE8 kernel data is in BE order whereas code stays in LE
> order. Move sigreturn_codes to separate .S file and use proper
> assembler mnemonics for these code snippets. In this case compiler
> will take care of proper instructions byteswaps for BE8 case.
> Change assumes that sufficiently Thumb-capable tools are used to
> build kernel.
>
> Problem was discovered during ltp testing of BE system: all rt_sig*
> tests failed. Tested against the same tests in both BE and LE modes.
>
> Signed-off-by: Victor Kamensky <victor.kamensky at linaro.org>
> Reviewed-by: Dave Martin <Dave.Martin at arm.com>
> Signed-off-by: Ben Dooks <ben.dooks at codethink.co.uk>
> ---
> arch/arm/kernel/Makefile | 3 +-
> arch/arm/kernel/signal.c | 24 +-----------
> arch/arm/kernel/sigreturn_codes.S | 80 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 83 insertions(+), 24 deletions(-)
> create mode 100644 arch/arm/kernel/sigreturn_codes.S
>
> diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
> index 5140df5f..39c9834 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -17,7 +17,8 @@ CFLAGS_REMOVE_return_address.o = -pg
>
> obj-y := elf.o entry-common.o irq.o opcodes.o \
> process.o ptrace.o return_address.o \
> - setup.o signal.o stacktrace.o sys_arm.o time.o traps.o
> + setup.o signal.o sigreturn_codes.o \
> + stacktrace.o sys_arm.o time.o traps.o
>
> obj-$(CONFIG_ATAGS) += atags_parse.o
> obj-$(CONFIG_ATAGS_PROC) += atags_proc.o
> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> index ab33042..64845fc 100644
> --- a/arch/arm/kernel/signal.c
> +++ b/arch/arm/kernel/signal.c
> @@ -21,29 +21,7 @@
> #include <asm/unistd.h>
> #include <asm/vfp.h>
>
> -/*
> - * For ARM syscalls, we encode the syscall number into the instruction.
> - */
> -#define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
> -#define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
> -
> -/*
> - * With EABI, the syscall number has to be loaded into r7.
> - */
> -#define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
> -#define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
> -
> -/*
> - * For Thumb syscalls, we pass the syscall number via r7. We therefore
> - * need two 16-bit instructions.
> - */
> -#define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
> -#define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
> -
> -static const unsigned long sigreturn_codes[7] = {
> - MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN,
> - MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
> -};
> +extern const unsigned long sigreturn_codes[7];
>
> static unsigned long signal_return_offset;
>
> diff --git a/arch/arm/kernel/sigreturn_codes.S b/arch/arm/kernel/sigreturn_codes.S
> new file mode 100644
> index 0000000..3c5d0f2
> --- /dev/null
> +++ b/arch/arm/kernel/sigreturn_codes.S
> @@ -0,0 +1,80 @@
> +/*
> + * sigreturn_codes.S - code sinpets for sigreturn syscalls
> + *
> + * Created by: Victor Kamensky, 2013-08-13
> + * Copyright: (C) 2013 Linaro Limited
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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.
> + */
> +
> +#include <asm/unistd.h>
> +
> +/*
> + * For ARM syscalls, we encode the syscall number into the instruction.
> + * With EABI, the syscall number has to be loaded into r7. As result
> + * ARM syscall sequence snippet will have move and svc in .arm encoding
> + *
> + * For Thumb syscalls, we pass the syscall number via r7. We therefore
> + * need two 16-bit instructions in .thumb encoding
> + *
> + * Please note sigreturn_codes code are not executed in place. Instead
> + * they just copied by kernel into appropriate places. Code inside of
> + * arch/arm/kernel/signal.c is very sensitive to layout of these code
> + * snippets.
> + */
> +
> +#if __LINUX_ARM_ARCH__ <= 4
> + /*
> + * Note we manually set minimally required arch that supports
> + * required thumb opcodes for early arch versions. It is OK
> + * for this file to be used in combination with other
> + * lower arch variants, since these code snippets are only
> + * used as input data.
> + */
> + .arch armv4t
> +#endif
> +
> + .section .rodata
> + .global sigreturn_codes
> + .type sigreturn_codes, #object
> +
> + .arm
This breaks a ARMv7-M build, see
http://arm-soc.lixom.net/buildlogs/misc/next-20131105-1-g2b29c44/buildall.arm.efm32_defconfig.log.failed
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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