From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Fri, 30 Aug 2013 15:00:03 +0100 Subject: [PATCH v3 1/1] ARM: signal: sigreturn_codes should be endian neutral to work in BE8 In-Reply-To: <1377668517-3722-2-git-send-email-victor.kamensky@linaro.org> References: <1377668517-3722-1-git-send-email-victor.kamensky@linaro.org> <1377668517-3722-2-git-send-email-victor.kamensky@linaro.org> Message-ID: <20130830135958.GA13352@localhost.localdomain> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Aug 27, 2013 at 10:41:57PM -0700, Victor Kamensky wrote: > 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. This looks OK to me. Reviewed-by: Dave Martin > > Signed-off-by: Victor Kamensky > --- > arch/arm/kernel/Makefile | 3 +- > arch/arm/kernel/signal.c | 24 +------------- > arch/arm/kernel/sigreturn_codes.S | 69 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 72 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 86d10dd..0722155 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 > #include > > -/* > - * 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..c888c43 > --- /dev/null > +++ b/arch/arm/kernel/sigreturn_codes.S > @@ -0,0 +1,69 @@ > +/* > + * 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 > + > +/* > + * 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. > + */ > + > + .section .rodata > + .global sigreturn_codes > + .type sigreturn_codes, #object > + > + .arm > + > +sigreturn_codes: > + > + /* ARM sigreturn syscall code snippet */ > + mov r7, #(__NR_sigreturn - __NR_SYSCALL_BASE) > + swi #(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE) > + > + /* Thumb sigreturn syscall code snippet */ > + .thumb > + movs r7, #(__NR_sigreturn - __NR_SYSCALL_BASE) > + swi #0 > + > + /* ARM sigreturn_rt syscall code snippet */ > + .arm > + mov r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE) > + swi #(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE) > + > + /* Thumb sigreturn_rt syscall code snippet */ > + .thumb > + movs r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE) > + swi #0 > + > + /* > + * Note on addtional space: setup_return in signal.c > + * algorithm uses two words copy regardless whether > + * it is thumb case or not, so we need additional > + * word after real last entry. > + */ > + .arm > + .space 4 > + > + .size sigreturn_codes, . - sigreturn_codes > -- > 1.8.1.4 > > > _______________________________________________ > linaro-kernel mailing list > linaro-kernel at lists.linaro.org > http://lists.linaro.org/mailman/listinfo/linaro-kernel