[PATCH 17/24] arm64: ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it

Yury Norov
2018-05-16T08:19:02Z

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>
Signed-off-by: Bamvor Jian Zhang <bamv2005@gmail.com>
---
arch/arm64/include/asm/unistd.h | 8 ++-
arch/arm64/include/uapi/asm/unistd.h | 12 ++++
arch/arm64/kernel/Makefile | 2 +-
arch/arm64/kernel/entry.S | 31 +++++++++-
arch/arm64/kernel/sys_ilp32.c | 90 ++++++++++++++++++++++++++++
5 files changed, 137 insertions(+), 6 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 99d29290c98b..1bf5572cd078 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -13,12 +13,16 @@
* 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_AARCH32_EL0
+
+#ifdef CONFIG_COMPAT
#define __ARCH_WANT_COMPAT_STAT64
+#define __ARCH_WANT_SYS_LLSEEK
+#endif
+
+#ifdef CONFIG_AARCH32_EL0
#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/include/uapi/asm/unistd.h b/arch/arm64/include/uapi/asm/unistd.h
index 439b1c55c827..80f1cb4ae2e1 100644
--- a/arch/arm64/include/uapi/asm/unistd.h
+++ b/arch/arm64/include/uapi/asm/unistd.h
@@ -15,7 +15,19 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

+/*
+ * Use AARCH32 interface for sys_sync_file_range() as it passes 64-bit arguments.
+ */
+#if defined(__ILP32__) || defined(__SYSCALL_COMPAT)
+#define __ARCH_WANT_SYNC_FILE_RANGE2
+#endif
+
+/*
+ * AARCH64/ILP32 is introduced after next syscalls were deprecated.
+ */
+#if !(defined(__ILP32__) || defined(__SYSCALL_COMPAT))
#define __ARCH_WANT_RENAMEAT
#define __ARCH_WANT_SET_GET_RLIMIT
+#endif

#include <asm-generic/unistd.h>
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 2dde9ae508ec..a6db407d4089 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -28,7 +28,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE

arm64-obj-$(CONFIG_AARCH32_EL0) += sys32.o kuser32.o signal32.o \
sys_compat.o entry32.o binfmt_elf32.o
-arm64-obj-$(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 698907724eed..d03542418f9b 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -401,6 +401,23 @@ 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.
*/
@@ -695,6 +712,7 @@ el0_svc_compat:
*/
ldr x16, [tsk, #TSK_TI_FLAGS] // load thread flags
adrp stbl, compat_sys_call_table // load compat syscall table pointer
+ ldr x19, [tsk, #TSK_TI_FLAGS]
mov wscno, w7 // syscall number in w7 (r7)
mov wsc_nr, #__NR_compat_syscalls
b el0_svc_naked
@@ -916,14 +934,15 @@ ENDPROC(ret_to_user)
el0_svc:
ldr x16, [tsk, #TSK_TI_FLAGS] // load thread flags
adrp stbl, sys_call_table // load syscall table pointer
+ ldr x19, [tsk, #TSK_TI_FLAGS]
mov wscno, w8 // syscall number in w8
mov wsc_nr, #__NR_syscalls

#ifdef CONFIG_ARM64_SVE
alternative_if_not ARM64_SVE
- b el0_svc_naked
+ b el0_svc_select_table
alternative_else_nop_endif
- tbz x16, #TIF_SVE, el0_svc_naked // Skip unless TIF_SVE set:
+ tbz x16, #TIF_SVE, el0_svc_select_table // Skip unless TIF_SVE set:
bic x16, x16, #_TIF_SVE // discard SVE state
str x16, [tsk, #TSK_TI_FLAGS]

@@ -939,12 +958,18 @@ alternative_else_nop_endif
msr cpacr_el1, x9 // synchronised by eret to el0
#endif

+el0_svc_select_table:
+#ifdef CONFIG_ARM64_ILP32
+ tbz x19, #TIF_32BIT_AARCH64, 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, xscno, [sp, #S_ORIG_X0] // save the original x0 and syscall number
enable_daif
ct_user_exit 1

- tst x16, #_TIF_SYSCALL_WORK // check for syscall hooks
+ tst x19, #_TIF_SYSCALL_WORK // check for syscall hooks
b.ne __sys_trace
cmp wscno, wsc_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 000000000000..9803d7806328
--- /dev/null
+++ b/arch/arm64/kernel/sys_ilp32.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * AArch64- ILP32 specific system calls implementation
+ *
+ * Copyright (C) 2018 Cavium Inc.
+ * Author: Andrew Pinski <apinski@cavium.com>
+ */
+
+#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>
+
+/*
+ * AARCH32 requires 4-page alignment for shared memory,
+ * but AARCH64 - only 1 page. This is the only difference
+ * between compat and native sys_shmat(). So ILP32 just pick
+ * AARCH64 version.
+ */
+#define compat_sys_shmat sys_shmat
+
+/*
+ * ILP32 needs special handling for some ptrace requests.
+ */
+#define sys_ptrace compat_sys_ptrace
+
+/*
+ * Using AARCH32 interface for syscalls that take 64-bit
+ * parameters in registers.
+ */
+#define compat_sys_fadvise64_64 compat_sys_fadvise64_64_wrapper
+#define compat_sys_fallocate compat_sys_fallocate_wrapper
+#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_sync_file_range2 compat_sys_sync_file_range2_wrapper
+#define compat_sys_truncate64 compat_sys_truncate64_wrapper
+#define sys_mmap2 compat_sys_mmap2_wrapper
+
+/*
+ * Using AARCH32 interface for syscalls that take the size of
+ * struct statfs as an argument, as it's calculated differently
+ * in kernel and user spaces.
+ */
+#define compat_sys_fstatfs64 compat_sys_fstatfs64_wrapper
+#define compat_sys_statfs64 compat_sys_statfs64_wrapper
+
+/*
+ * Using custom wrapper for rt_sigreturn() to handle custom
+ * struct rt_sigframe.
+ */
+#define compat_sys_rt_sigreturn ilp32_sys_rt_sigreturn_wrapper
+
+asmlinkage long compat_sys_fstatfs64_wrapper(void);
+asmlinkage long compat_sys_statfs64_wrapper(void);
+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);
+
+#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>
+};
--
2.17.0