[tip: core/entry] x86/entry: Get rid of the sys_ni_syscall() indirection

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     1b1f3b3e1b3945ae6e49081fd3586a6833d4a555
Gitweb:        https://git.kernel.org/tip/1b1f3b3e1b3945ae6e49081fd3586a6833d4a555
Author:        Thomas Gleixner <tglx@xxxxxxxxxx>
AuthorDate:    Tue, 07 Jul 2026 21:07:01 +02:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Sun, 12 Jul 2026 12:38:02 +02:00

x86/entry: Get rid of the sys_ni_syscall() indirection

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@xxxxxxxxxx>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@xxxxxxxxx>
Reviewed-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Link: https://patch.msgid.link/20260707190254.493733289@xxxxxxxxxx
---
 arch/x86/entry/syscall_32.c |  2 --
 arch/x86/entry/syscall_64.c | 10 +++-------
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c
index 6e00929..68e2f13 100644
--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -81,8 +81,6 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, int nr)
 	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);
 	}
 }
 
diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
index 837aee7..c716e0f 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -68,7 +68,7 @@ static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr)
 	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_x32(struct pt_regs *regs, int nr)
 	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 @@ __visible noinstr bool do_syscall_64(struct pt_regs *regs, int nr)
 
 	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);