arm64: Implement the compat_sys_call_table in C

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@arm.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>

4 files changed, 65 insertions, 24 deletions

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 77d3d9568333..3b3b1cd3e7f0 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 cacheinfo.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 02e6af117762..cf21bb3bf752 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
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>
+};