Re: [PATCH 14/19] arm64: ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it

[Yury Norov]

On Sat, Jun 18, 2016 at 02:54:23AM +0300, Yury Norov wrote:
> From: Andrew Pinski <apinski@xxxxxxxxxx>
> 
> Add a separate syscall-table for ILP32, which dispatches either to native
> LP64 system call implementation or to compat-syscalls, as appropriate.
> 
> Signed-off-by: Andrew Pinski <Andrew.Pinski@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
> ---
>  arch/arm64/include/asm/unistd.h |  6 ++-
>  arch/arm64/kernel/Makefile      |  2 +-
>  arch/arm64/kernel/entry.S       | 29 +++++++++++++-
>  arch/arm64/kernel/sys_ilp32.c   | 84 +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 117 insertions(+), 4 deletions(-)
>  create mode 100644 arch/arm64/kernel/sys_ilp32.c
> 
> diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
> index fe9d6c1..250654c 100644
> --- a/arch/arm64/include/asm/unistd.h
> +++ b/arch/arm64/include/asm/unistd.h
> @@ -13,13 +13,17 @@
>   * You should have received a copy of the GNU General Public License
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
> +
> +#ifdef CONFIG_COMPAT
> +#define __ARCH_WANT_SYS_LLSEEK
> +#endif
> +
>  #ifdef CONFIG_AARCH32_EL0
>  #define __ARCH_WANT_COMPAT_SYS_GETDENTS64
>  #define __ARCH_WANT_COMPAT_STAT64
>  #define __ARCH_WANT_SYS_GETHOSTNAME
>  #define __ARCH_WANT_SYS_PAUSE
>  #define __ARCH_WANT_SYS_GETPGRP
> -#define __ARCH_WANT_SYS_LLSEEK
>  #define __ARCH_WANT_SYS_NICE
>  #define __ARCH_WANT_SYS_SIGPENDING
>  #define __ARCH_WANT_SYS_SIGPROCMASK
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index d11572d..205bc03 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -28,7 +28,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
>  arm64-obj-$(CONFIG_AARCH32_EL0)		+= sys32.o kuser32.o signal32.o 	\
>  					   sys_compat.o entry32.o		\
>  					   ../../arm/kernel/opcodes.o binfmt_elf32.o
> -arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o
> +arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o sys_ilp32.o
>  arm64-obj-$(CONFIG_COMPAT)		+= entry32_common.o
>  arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
>  arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 21a0624..b2b9725 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -239,6 +239,23 @@ tsk	.req	x28		// current thread_info
>  
>  	.text
>  
> +#ifdef CONFIG_ARM64_ILP32
> +/*
> + * AARCH64/ILP32. Zero top halves of x0-x7
> + * registers as userspace may put garbage there.
> + */
> +	.macro	delouse_input_regs
> +	mov w0, w0
> +	mov w1, w1
> +	mov w2, w2
> +	mov w3, w3
> +	mov w4, w4
> +	mov w5, w5
> +	mov w6, w6
> +	mov w7, w7
> +	.endm
> +#endif
> +
>  /*
>   * Exception vectors.
>   */
> @@ -501,6 +518,7 @@ el0_svc_compat:
>  	 * AArch32 syscall handling
>  	 */
>  	adrp	stbl, compat_sys_call_table	// load compat syscall table pointer
> +	ldr     x16, [tsk, #TI_FLAGS]
>  	uxtw	scno, w7			// syscall number in w7 (r7)
>  	mov     sc_nr, #__NR_compat_syscalls
>  	b	el0_svc_naked
> @@ -717,15 +735,22 @@ ENDPROC(ret_from_fork)
>  	.align	6
>  el0_svc:
>  	adrp	stbl, sys_call_table		// load syscall table pointer
> +	ldr	x16, [tsk, #TI_FLAGS]
>  	uxtw	scno, w8			// syscall number in w8
>  	mov	sc_nr, #__NR_syscalls
> +#ifdef CONFIG_ARM64_ILP32
> +	adrp	x17, sys_call_ilp32_table	// load ilp32 syscall table pointer
> +	tst	x16, #_TIF_32BIT_AARCH64
> +	b.eq	el0_svc_naked			// We are using LP64  syscall table
> +	mov	stbl, x17			// We are using ILP32 syscall table
> +	delouse_input_regs
> +#endif

It should be like this:
#ifdef CONFIG_ARM64_ILP32
        tst     x16, #_TIF_32BIT_AARCH64
        b.eq    el0_svc_naked                   // We are using LP64  syscall table
        adrp    stbl, sys_call_ilp32_table      // load ilp32 syscall table pointer
        delouse_input_regs
#endif

>  el0_svc_naked:					// compat entry point
>  	stp	x0, scno, [sp, #S_ORIG_X0]	// save the original x0 and syscall number
>  	enable_dbg_and_irq
>  	ct_user_exit 1
>  
> -	ldr	x16, [tsk, #TI_FLAGS]		// check for syscall hooks
> -	tst	x16, #_TIF_SYSCALL_WORK
> +	tst	x16, #_TIF_SYSCALL_WORK		// check for syscall hooks
>  	b.ne	__sys_trace
>  	cmp     scno, sc_nr                     // check upper syscall limit
>  	b.hs	ni_sys
> diff --git a/arch/arm64/kernel/sys_ilp32.c b/arch/arm64/kernel/sys_ilp32.c
> new file mode 100644
> index 0000000..00c4d4b
> --- /dev/null
> +++ b/arch/arm64/kernel/sys_ilp32.c
> @@ -0,0 +1,84 @@
> +/*
> + * AArch64- ILP32 specific system calls implementation
> + *
> + * Copyright (C) 2016 Cavium Inc.
> + * Author: Andrew Pinski <apinski@xxxxxxxxxx>
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#define __SYSCALL_COMPAT
> +
> +#include <linux/compiler.h>
> +#include <linux/errno.h>
> +#include <linux/fs.h>
> +#include <linux/mm.h>
> +#include <linux/msg.h>
> +#include <linux/export.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/syscalls.h>
> +#include <linux/compat.h>
> +#include <asm-generic/syscalls.h>
> +
> +/*
> + * Using aarch32 syscall handlerss where off_t is passed.
> + */
> +#define compat_sys_fadvise64_64		compat_sys_fadvise64_64_wrapper
> +#define compat_sys_fallocate		compat_sys_fallocate_wrapper
> +#define compat_sys_fcntl64		sys_fcntl
> +#define compat_sys_ftruncate64		compat_sys_ftruncate64_wrapper
> +#define compat_sys_pread64		compat_sys_pread64_wrapper
> +#define compat_sys_pwrite64		compat_sys_pwrite64_wrapper
> +#define compat_sys_readahead		compat_sys_readahead_wrapper
> +#define compat_sys_shmat		sys_shmat
> +#define compat_sys_sync_file_range	compat_sys_sync_file_range2_wrapper
> +#define compat_sys_truncate64		compat_sys_truncate64_wrapper
> +#define sys_mmap2			compat_sys_mmap2_wrapper
> +#define sys_ptrace			compat_sys_ptrace
> +
> +/*
> + * Use non-compat syscall handlerss where stat and statfs structure
> + * pointers are passed, as their layout is identical to LP64.
> + */
> +#define compat_sys_fstatfs64		sys_fstatfs
> +#define compat_sys_statfs64		sys_statfs
> +#define sys_fstat64			sys_newfstat
> +#define sys_fstatat64			sys_newfstatat
> +
> +asmlinkage long compat_sys_fadvise64_64_wrapper(void);
> +asmlinkage long compat_sys_fallocate_wrapper(void);
> +asmlinkage long compat_sys_ftruncate64_wrapper(void);
> +asmlinkage long compat_sys_mmap2_wrapper(void);
> +asmlinkage long compat_sys_pread64_wrapper(void);
> +asmlinkage long compat_sys_pwrite64_wrapper(void);
> +asmlinkage long compat_sys_readahead_wrapper(void);
> +asmlinkage long compat_sys_sync_file_range2_wrapper(void);
> +asmlinkage long compat_sys_truncate64_wrapper(void);
> +
> +asmlinkage long ilp32_sys_rt_sigreturn_wrapper(void);
> +#define compat_sys_rt_sigreturn        ilp32_sys_rt_sigreturn_wrapper
> +
> +#include <asm/syscall.h>
> +
> +#undef __SYSCALL
> +#define __SYSCALL(nr, sym)	[nr] = sym,
> +
> +/*
> + * The sys_call_ilp32_table array must be 4K aligned to be accessible from
> + * kernel/entry.S.
> + */
> +void *sys_call_ilp32_table[__NR_syscalls] __aligned(4096) = {
> +	[0 ... __NR_syscalls - 1] = sys_ni_syscall,
> +#include <asm/unistd.h>
> +};
> -- 
> 2.7.4