arch/x86/um/shared/sysdep/stub_32.h

Source file repositories/reference/linux-study-clean/arch/x86/um/shared/sysdep/stub_32.h

File Facts

System
Linux kernel
Corpus path
arch/x86/um/shared/sysdep/stub_32.h
Extension
.h
Size
2940 bytes
Lines
148
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source 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

struct syscall_args {
		int ebx, ebp;
	} args = { arg1, arg6 };
	long ret;

	__asm__ volatile ("pushl %%ebp;"
			"movl 0x4(%%ebx),%%ebp;"
			"movl (%%ebx),%%ebx;"
			"int $0x80;"
			"popl %%ebp"
			: "=a" (ret)
			: "0" (syscall), "b" (&args),
			"c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
			: "memory");

	return ret;
}

static __always_inline void trap_myself(void)
{
	__asm("int3");
}

static __always_inline void *get_stub_data(void)
{
	unsigned long ret;

	asm volatile (
		"call _here_%=;"
		"_here_%=:"
		"popl %0;"
		"andl %1, %0 ;"
		"addl %2, %0 ;"
		: "=a" (ret)
		: "g" (~(UM_KERN_PAGE_SIZE - 1)),
		  "g" (UM_KERN_PAGE_SIZE));

	return (void *)ret;
}

#define stub_start(fn)							\
	asm volatile (							\
		"subl %0,%%esp ;"					\
		"movl %1, %%eax ; "					\
		"call *%%eax ;"						\
		:: "i" (STUB_SIZE),					\
		   "i" (&fn))

static __always_inline void
stub_seccomp_restore_state(struct stub_data_arch *arch)
{
	for (int i = 0; i < sizeof(arch->tls) / sizeof(arch->tls[0]); i++) {
		if (arch->sync & (1 << i))
			stub_syscall1(__NR_set_thread_area,
				      (unsigned long) &arch->tls[i]);
	}

	arch->sync = 0;
}

#endif

Annotation

Implementation Notes