[PATCH 3/5] arm64: Implement the compat_sys_call_table in C

From: Catalin Marinas
Date: Fri Jan 09 2015 - 10:58:38 EST

Unlike the sys_call_table[], the compat one was implemented in sys32.S
making it impossible to notice discrepancies between the number of
compat syscalls and the __NR_compat_syscalls macro, the latter having to
be defined in asm/unistd.h as including asm/unistd32.h would cause
conflicts on __NR_* definitions. With this patch, incorrect
__NR_compat_syscalls values will result in a build-time error.

Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
---
arch/arm64/include/asm/unistd.h | 3 ++
arch/arm64/kernel/Makefile | 2 +-
arch/arm64/kernel/entry.S | 2 +-
arch/arm64/kernel/{sys32.S => entry32.S} | 34 ++++++++-------------
arch/arm64/kernel/sys32.c | 51 ++++++++++++++++++++++++++++++++
5 files changed, 68 insertions(+), 24 deletions(-)
rename arch/arm64/kernel/{sys32.S => entry32.S} (80%)
create mode 100644 arch/arm64/kernel/sys32.c

diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index b780c6c76eec..159b44fff258 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -48,6 +48,9 @@
#endif

#define __ARCH_WANT_SYS_CLONE
+
+#ifndef __COMPAT_SYSCALL_NR
#include <uapi/asm/unistd.h>
+#endif

#define NR_syscalls (__NR_syscalls)
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index eaa77ed7766a..54be7dc906f0 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -19,7 +19,7 @@ arm64-obj-y := cputable.o debug-monitors.o entry.o irq.o fpsimd.o \
cpuinfo.o cpu_errata.o alternative.o

arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \
- sys_compat.o \
+ sys_compat.o entry32.o \
../../arm/kernel/opcodes.o
arm64-obj-$(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 fd4fa374e5d2..39811ad31537 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -433,7 +433,7 @@ el0_svc_compat:
/*
* AArch32 syscall handling
*/
- adr stbl, compat_sys_call_table // load compat syscall table pointer
+ adrp stbl, compat_sys_call_table // load compat syscall table pointer
uxtw scno, w7 // syscall number in w7 (r7)
mov sc_nr, #__NR_compat_syscalls
b el0_svc_naked
diff --git a/arch/arm64/kernel/sys32.S b/arch/arm64/kernel/entry32.S
similarity index 80%
rename from arch/arm64/kernel/sys32.S
rename to arch/arm64/kernel/entry32.S
index 423a5b3fc2be..9a8f6ae2530e 100644
--- a/arch/arm64/kernel/sys32.S
+++ b/arch/arm64/kernel/entry32.S
@@ -27,26 +27,26 @@
* System call wrappers for the AArch32 compatibility layer.
*/

-compat_sys_sigreturn_wrapper:
+ENTRY(compat_sys_sigreturn_wrapper)
mov x0, sp
mov x27, #0 // prevent syscall restart handling (why)
b compat_sys_sigreturn
ENDPROC(compat_sys_sigreturn_wrapper)

-compat_sys_rt_sigreturn_wrapper:
+ENTRY(compat_sys_rt_sigreturn_wrapper)
mov x0, sp
mov x27, #0 // prevent syscall restart handling (why)
b compat_sys_rt_sigreturn
ENDPROC(compat_sys_rt_sigreturn_wrapper)

-compat_sys_statfs64_wrapper:
+ENTRY(compat_sys_statfs64_wrapper)
mov w3, #84
cmp w1, #88
csel w1, w3, w1, eq
b compat_sys_statfs64
ENDPROC(compat_sys_statfs64_wrapper)

-compat_sys_fstatfs64_wrapper:
+ENTRY(compat_sys_fstatfs64_wrapper)
mov w3, #84
cmp w1, #88
csel w1, w3, w1, eq
@@ -58,33 +58,33 @@ ENDPROC(compat_sys_fstatfs64_wrapper)
* in registers or that take 32-bit parameters which require sign
* extension.
*/
-compat_sys_pread64_wrapper:
+ENTRY(compat_sys_pread64_wrapper)
regs_to_64 x3, x4, x5
b sys_pread64
ENDPROC(compat_sys_pread64_wrapper)

-compat_sys_pwrite64_wrapper:
+ENTRY(compat_sys_pwrite64_wrapper)
regs_to_64 x3, x4, x5
b sys_pwrite64
ENDPROC(compat_sys_pwrite64_wrapper)

-compat_sys_truncate64_wrapper:
+ENTRY(compat_sys_truncate64_wrapper)
regs_to_64 x1, x2, x3
b sys_truncate
ENDPROC(compat_sys_truncate64_wrapper)

-compat_sys_ftruncate64_wrapper:
+ENTRY(compat_sys_ftruncate64_wrapper)
regs_to_64 x1, x2, x3
b sys_ftruncate
ENDPROC(compat_sys_ftruncate64_wrapper)

-compat_sys_readahead_wrapper:
+ENTRY(compat_sys_readahead_wrapper)
regs_to_64 x1, x2, x3
mov w2, w4
b sys_readahead
ENDPROC(compat_sys_readahead_wrapper)

-compat_sys_fadvise64_64_wrapper:
+ENTRY(compat_sys_fadvise64_64_wrapper)
mov w6, w1
regs_to_64 x1, x2, x3
regs_to_64 x2, x4, x5
@@ -92,24 +92,14 @@ compat_sys_fadvise64_64_wrapper:
b sys_fadvise64_64
ENDPROC(compat_sys_fadvise64_64_wrapper)

-compat_sys_sync_file_range2_wrapper:
+ENTRY(compat_sys_sync_file_range2_wrapper)
regs_to_64 x2, x2, x3
regs_to_64 x3, x4, x5
b sys_sync_file_range2
ENDPROC(compat_sys_sync_file_range2_wrapper)

-compat_sys_fallocate_wrapper:
+ENTRY(compat_sys_fallocate_wrapper)
regs_to_64 x2, x2, x3
regs_to_64 x3, x4, x5
b sys_fallocate
ENDPROC(compat_sys_fallocate_wrapper)
-
-#undef __SYSCALL
-#define __SYSCALL(x, y) .quad y // x
-
-/*
- * The system calls table must be 4KB aligned.
- */
- .align 12
-ENTRY(compat_sys_call_table)
-#include <asm/unistd32.h>
diff --git a/arch/arm64/kernel/sys32.c b/arch/arm64/kernel/sys32.c
new file mode 100644
index 000000000000..2d5ab3c90b82
--- /dev/null
+++ b/arch/arm64/kernel/sys32.c
@@ -0,0 +1,51 @@
+/*
+ * arch/arm64/kernel/sys32.c
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ *
+ * This program is free software(void); 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(void);//www.gnu.org/licenses/>.
+ */
+
+/*
+ * Needed to avoid conflicting __NR_* macros between uapi/asm/unistd.h and
+ * asm/unistd32.h.
+ */
+#define __COMPAT_SYSCALL_NR
+
+#include <linux/compiler.h>
+#include <linux/syscalls.h>
+
+asmlinkage long compat_sys_sigreturn_wrapper(void);
+asmlinkage long compat_sys_rt_sigreturn_wrapper(void);
+asmlinkage long compat_sys_statfs64_wrapper(void);
+asmlinkage long compat_sys_fstatfs64_wrapper(void);
+asmlinkage long compat_sys_pread64_wrapper(void);
+asmlinkage long compat_sys_pwrite64_wrapper(void);
+asmlinkage long compat_sys_truncate64_wrapper(void);
+asmlinkage long compat_sys_ftruncate64_wrapper(void);
+asmlinkage long compat_sys_readahead_wrapper(void);
+asmlinkage long compat_sys_fadvise64_64_wrapper(void);
+asmlinkage long compat_sys_sync_file_range2_wrapper(void);
+asmlinkage long compat_sys_fallocate_wrapper(void);
+
+#undef __SYSCALL
+#define __SYSCALL(nr, sym) [nr] = sym,
+
+/*
+ * The sys_call_table array must be 4K aligned to be accessible from
+ * kernel/entry.S.
+ */
+void * const compat_sys_call_table[__NR_compat_syscalls] __aligned(4096) = {
+ [0 ... __NR_compat_syscalls - 1] = sys_ni_syscall,
+#include <asm/unistd32.h>
+};
--
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