[patch 16/18] x86/entry: Get rid of the sys_ni_syscall() indirection

[Thomas Gleixner]

Invoking sys_ni_syscall() from a code path, which already knows that the
syscall number is invalid just to assign -ENOSYS to regs->ax is a pointless
exercise. It's even redundant as the low level entry code already has set
regs->ax to -ENOSYS on entry.

Remove the extra conditionals and the function calls.

Signed-off-by: Thomas Gleixner <tglx at kernel.org>
---
 arch/x86/entry/syscall_32.c |    2 --
 arch/x86/entry/syscall_64.c |   10 +++-------
 2 files changed, 3 insertions(+), 9 deletions(-)

--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -81,8 +81,6 @@ static __always_inline void do_syscall_3
 	if (likely(unr < IA32_NR_syscalls)) {
 		unr = array_index_nospec(unr, IA32_NR_syscalls);
 		regs->ax = ia32_sys_call(regs, unr);
-	} else if (nr != -1) {
-		regs->ax = __ia32_sys_ni_syscall(regs);
 	}
 }
 
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -68,7 +68,7 @@ static __always_inline bool do_syscall_x
 	return false;
 }
 
-static __always_inline bool do_syscall_x32(struct pt_regs *regs, int nr)
+static __always_inline void do_syscall_x32(struct pt_regs *regs, int nr)
 {
 	/*
 	 * Adjust the starting offset of the table, and convert numbers
@@ -80,9 +80,7 @@ static __always_inline bool do_syscall_x
 	if (IS_ENABLED(CONFIG_X86_X32_ABI) && likely(xnr < X32_NR_syscalls)) {
 		xnr = array_index_nospec(xnr, X32_NR_syscalls);
 		regs->ax = x32_sys_call(regs, xnr);
-		return true;
 	}
-	return false;
 }
 
 /* Returns true to return using SYSRET, or false to use IRET */
@@ -92,10 +90,8 @@ static __always_inline bool do_syscall_x
 
 	instrumentation_begin();
 
-	if (!do_syscall_x64(regs, nr) && !do_syscall_x32(regs, nr) && nr != -1) {
-		/* Invalid system call, but still a system call. */
-		regs->ax = __x64_sys_ni_syscall(regs);
-	}
+	if (!do_syscall_x64(regs, nr))
+		do_syscall_x32(regs, nr);
 
 	instrumentation_end();
 	syscall_exit_to_user_mode(regs);