tools/testing/selftests/x86/entry_from_vm86.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/x86/entry_from_vm86.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/x86/entry_from_vm86.c
Extension
.c
Size
9315 bytes
Lines
329
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct table_desc {
		unsigned short limit;
		unsigned long base;
	} __attribute__((packed));

	/* Initialize variables with arbitrary values */
	struct table_desc gdt1 = { .base = 0x3c3c3c3c, .limit = 0x9999 };
	struct table_desc gdt2 = { .base = 0x1a1a1a1a, .limit = 0xaeae };
	struct table_desc idt1 = { .base = 0x7b7b7b7b, .limit = 0xf1f1 };
	struct table_desc idt2 = { .base = 0x89898989, .limit = 0x1313 };
	unsigned short msw1 = 0x1414, msw2 = 0x2525, msw3 = 3737;

	/* UMIP -- exit with INT3 unless kernel emulation did not trap #GP */
	do_test(vm86, vmcode_umip - vmcode, VM86_TRAP, 3, "UMIP tests");

	/* Results from displacement-only addressing */
	msw1 = *(unsigned short *)(test_mem + 2052);
	memcpy(&idt1, test_mem + 2054, sizeof(idt1));
	memcpy(&gdt1, test_mem + 2060, sizeof(gdt1));

	/* Results from register-indirect addressing */
	msw2 = *(unsigned short *)(test_mem + 2066);
	memcpy(&idt2, test_mem + 2068, sizeof(idt2));
	memcpy(&gdt2, test_mem + 2074, sizeof(gdt2));

	/* Results when using register operands */
	msw3 = *(unsigned short *)(test_mem + 2080);

	printf("[INFO]\tResult from SMSW:[0x%04x]\n", msw1);
	printf("[INFO]\tResult from SIDT: limit[0x%04x]base[0x%08lx]\n",
	       idt1.limit, idt1.base);
	printf("[INFO]\tResult from SGDT: limit[0x%04x]base[0x%08lx]\n",
	       gdt1.limit, gdt1.base);

	if (msw1 != msw2 || msw1 != msw3)
		printf("[FAIL]\tAll the results of SMSW should be the same.\n");
	else
		printf("[PASS]\tAll the results from SMSW are identical.\n");

	if (memcmp(&gdt1, &gdt2, sizeof(gdt1)))
		printf("[FAIL]\tAll the results of SGDT should be the same.\n");
	else
		printf("[PASS]\tAll the results from SGDT are identical.\n");

	if (memcmp(&idt1, &idt2, sizeof(idt1)))
		printf("[FAIL]\tAll the results of SIDT should be the same.\n");
	else
		printf("[PASS]\tAll the results from SIDT are identical.\n");

	sethandler(SIGILL, sighandler, 0);
	do_test(vm86, vmcode_umip_str - vmcode, VM86_SIGNAL, 0,
		"STR instruction");
	clearhandler(SIGILL);

	sethandler(SIGILL, sighandler, 0);
	do_test(vm86, vmcode_umip_sldt - vmcode, VM86_SIGNAL, 0,
		"SLDT instruction");
	clearhandler(SIGILL);
}

int main(void)
{
	struct vm86plus_struct v86;
	unsigned char *addr = mmap((void *)load_addr, 4096,
				   PROT_READ | PROT_WRITE | PROT_EXEC,
				   MAP_ANONYMOUS | MAP_PRIVATE, -1,0);
	if (addr != (unsigned char *)load_addr)
		err(1, "mmap");

	memcpy(addr, vmcode, end_vmcode - vmcode);
	addr[2048] = 2;
	addr[2050] = 3;

	memset(&v86, 0, sizeof(v86));

	v86.regs.cs = load_addr / 16;
	v86.regs.ss = load_addr / 16;
	v86.regs.ds = load_addr / 16;
	v86.regs.es = load_addr / 16;

	/* Use the end of the page as our stack. */
	v86.regs.esp = 4096;

	assert((v86.regs.cs & 3) == 0);	/* Looks like RPL = 0 */

	/* #BR -- should deliver SIG??? */
	do_test(&v86, vmcode_bound - vmcode, VM86_INTx, 5, "#BR");

	/*
	 * SYSENTER -- should cause #GP or #UD depending on CPU.

Annotation

Implementation Notes