arch/x86/entry/syscall_32.c

Source file repositories/reference/linux-study-clean/arch/x86/entry/syscall_32.c

File Facts

System
Linux kernel
Corpus path
arch/x86/entry/syscall_32.c
Extension
.c
Size
10987 bytes
Lines
372
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/* 32-bit system call dispatch */

#include <linux/linkage.h>
#include <linux/sys.h>
#include <linux/cache.h>
#include <linux/syscalls.h>
#include <linux/entry-common.h>
#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <asm/apic.h>
#include <asm/traps.h>
#include <asm/cpufeature.h>
#include <asm/syscall.h>

#ifdef CONFIG_IA32_EMULATION
#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)
#else
#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
#endif

#define __SYSCALL(nr, sym) extern long __ia32_##sym(const struct pt_regs *);
#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __ia32_##sym(const struct pt_regs *);
#include <asm/syscalls_32.h>
#undef  __SYSCALL

#undef  __SYSCALL_NORETURN
#define __SYSCALL_NORETURN __SYSCALL

/*
 * The sys_call_table[] is no longer used for system calls, but
 * kernel/trace/trace_syscalls.c still wants to know the system
 * call address.
 */
#ifdef CONFIG_X86_32
#define __SYSCALL(nr, sym) __ia32_##sym,
const sys_call_ptr_t sys_call_table[] = {
#include <asm/syscalls_32.h>
};
#undef  __SYSCALL
#endif

#define __SYSCALL(nr, sym) case nr: return __ia32_##sym(regs);
long ia32_sys_call(const struct pt_regs *regs, unsigned int nr)
{
	switch (nr) {
	#include <asm/syscalls_32.h>
	default: return __ia32_sys_ni_syscall(regs);
	}
}

static __always_inline int syscall_32_enter(struct pt_regs *regs)
{
	if (IS_ENABLED(CONFIG_IA32_EMULATION))
		current_thread_info()->status |= TS_COMPAT;

	return (int)regs->orig_ax;
}

#ifdef CONFIG_IA32_EMULATION
bool __ia32_enabled __ro_after_init = !IS_ENABLED(CONFIG_IA32_EMULATION_DEFAULT_DISABLED);

static int __init ia32_emulation_override_cmdline(char *arg)
{
	return kstrtobool(arg, &__ia32_enabled);
}
early_param("ia32_emulation", ia32_emulation_override_cmdline);
#endif

/*
 * Invoke a 32-bit syscall.  Called with IRQs on in CT_STATE_KERNEL.
 */
static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, int nr)
{
	/*
	 * Convert negative numbers to very high and thus out of range
	 * numbers for comparisons.
	 */
	unsigned int unr = 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);
	}
}

#ifdef CONFIG_IA32_EMULATION
static __always_inline bool int80_is_external(void)

Annotation

Implementation Notes