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    SubjectRe: [PATCH 14/19] arm64: ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it
    On Sat, Jun 18, 2016 at 02:54:23AM +0300, Yury Norov wrote:
    > From: Andrew Pinski <apinski@cavium.com>
    >
    > 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@caviumnetworks.com>
    > Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
    > ---
    > 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@cavium.com>
    > + *
    > + * 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
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