[patch V4 11/36] entry: Remove syscall_enter_from_user_mode_prepare()

Thomas Gleixner
2025-09-08T21:31:50Z

Open code the only user in the x86 syscall code and reduce the zoo of
functions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org

---
arch/x86/entry/syscall_32.c | 3 ++-
include/linux/entry-common.h | 26 +++++---------------------
kernel/entry/syscall-common.c | 8 --------
3 files changed, 7 insertions(+), 30 deletions(-)

--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -274,9 +274,10 @@ static noinstr bool __do_fast_syscall_32
* fetch EBP before invoking any of the syscall entry work
* functions.
*/
- syscall_enter_from_user_mode_prepare(regs);
+ enter_from_user_mode(regs);

instrumentation_begin();
+ local_irq_enable();
/* Fetch EBP from where the vDSO stashed it. */
if (IS_ENABLED(CONFIG_X86_64)) {
/*
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -45,23 +45,6 @@
SYSCALL_WORK_SYSCALL_EXIT_TRAP | \
ARCH_SYSCALL_WORK_EXIT)

-/**
- * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
- * @regs: Pointer to currents pt_regs
- *
- * Invoked from architecture specific syscall entry code with interrupts
- * disabled. The calling code has to be non-instrumentable. When the
- * function returns all state is correct, interrupts are enabled and the
- * subsequent functions can be instrumented.
- *
- * This handles lockdep, RCU (context tracking) and tracing state, i.e.
- * the functionality provided by enter_from_user_mode().
- *
- * This is invoked when there is extra architecture specific functionality
- * to be done between establishing state and handling user mode entry work.
- */
-void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
-
long syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long work);

/**
@@ -71,8 +54,8 @@ long syscall_trace_enter(struct pt_regs
* @syscall: The syscall number
*
* Invoked from architecture specific syscall entry code with interrupts
- * enabled after invoking syscall_enter_from_user_mode_prepare() and extra
- * architecture specific work.
+ * enabled after invoking enter_from_user_mode(), enabling interrupts and
+ * extra architecture specific work.
*
* Returns: The original or a modified syscall number
*
@@ -108,8 +91,9 @@ static __always_inline long syscall_ente
* function returns all state is correct, interrupts are enabled and the
* subsequent functions can be instrumented.
*
- * This is combination of syscall_enter_from_user_mode_prepare() and
- * syscall_enter_from_user_mode_work().
+ * This is the combination of enter_from_user_mode() and
+ * syscall_enter_from_user_mode_work() to be used when there is no
+ * architecture specific work to be done between the two.
*
* Returns: The original or a modified syscall number. See
* syscall_enter_from_user_mode_work() for further explanation.
--- a/kernel/entry/syscall-common.c
+++ b/kernel/entry/syscall-common.c
@@ -63,14 +63,6 @@ long syscall_trace_enter(struct pt_regs
return ret ? : syscall;
}

-noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
-{
- enter_from_user_mode(regs);
- instrumentation_begin();
- local_irq_enable();
- instrumentation_end();
-}
-
/*
* If SYSCALL_EMU is set, then the only reason to report is when
* SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall