[PATCH] arm64: fix function types in COND_SYSCALL

[Sami Tolvanen]

Define a weak function in COND_SYSCALL instead of a weak alias to
sys_ni_syscall, which has an incompatible type. This fixes indirect
call mismatches with Control-Flow Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen <samitolva...@google.com>
---
 arch/arm64/include/asm/syscall_wrapper.h | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/syscall_wrapper.h 
b/arch/arm64/include/asm/syscall_wrapper.h
index 507d0ee6bc69..06d880b3526c 100644
--- a/arch/arm64/include/asm/syscall_wrapper.h
+++ b/arch/arm64/include/asm/syscall_wrapper.h
@@ -8,6 +8,8 @@
 #ifndef __ASM_SYSCALL_WRAPPER_H
 #define __ASM_SYSCALL_WRAPPER_H
 
+struct pt_regs;
+
 #define SC_ARM64_REGS_TO_ARGS(x, ...)                          \
        __MAP(x,__SC_ARGS                                       \
              ,,regs->regs[0],,regs->regs[1],,regs->regs[2]     \
@@ -35,8 +37,11 @@
        ALLOW_ERROR_INJECTION(__arm64_compat_sys_##sname, ERRNO);               
        \
        asmlinkage long __arm64_compat_sys_##sname(const struct pt_regs 
*__unused)
 
-#define COND_SYSCALL_COMPAT(name) \
-       cond_syscall(__arm64_compat_sys_##name);
+#define COND_SYSCALL_COMPAT(name)                                              
        \
+       asmlinkage long __weak __arm64_compat_sys_##name(const struct pt_regs 
*regs)    \
+       {                                                                       
        \
+               return sys_ni_syscall();                                        
        \
+       }
 
 #define COMPAT_SYS_NI(name) \
        SYSCALL_ALIAS(__arm64_compat_sys_##name, sys_ni_posix_timers);
@@ -70,7 +75,11 @@
 #endif
 
 #ifndef COND_SYSCALL
-#define COND_SYSCALL(name) cond_syscall(__arm64_sys_##name)
+#define COND_SYSCALL(name)                                                     
\
+       asmlinkage long __weak __arm64_sys_##name(const struct pt_regs *regs)   
\
+       {                                                                       
\
+               return sys_ni_syscall();                                        
\
+       }
 #endif
 
 #ifndef SYS_NI
-- 
2.23.0.162.g0b9fbb3734-goog