x86/asm/entry/32, selftests: Add a selftest for kernel entries from VM86 mode (c2affbf9) · Commits · 戴 / test

tools/testing/selftests/x86/Makefile

+4 −2

Original line number	Diff line number	Diff line
		@@ -5,8 +5,10 @@ include ../lib.mk
		.PHONY: all all_32 all_64 warn_32bit_failure clean

		TARGETS_C_BOTHBITS := sigreturn single_step_syscall
		TARGETS_C_32BIT_ONLY := entry_from_vm86

		BINARIES_32 := $(TARGETS_C_BOTHBITS:%=%_32)
		TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
		BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)
		BINARIES_64 := $(TARGETS_C_BOTHBITS:%=%_64)

		CFLAGS := -O2 -g -std=gnu99 -pthread -Wall
		@@ -32,7 +34,7 @@ all_64: $(BINARIES_64)
		clean:
		$(RM) $(BINARIES_32) $(BINARIES_64)

		$(TARGETS_C_BOTHBITS:%=%_32): %_32: %.c
		$(TARGETS_C_32BIT_ALL:%=%_32): %_32: %.c
		$(CC) -m32 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl

		$(TARGETS_C_BOTHBITS:%=%_64): %_64: %.c

tools/testing/selftests/x86/entry_from_vm86.c

0 → 100644

+114 −0

Original line number	Diff line number	Diff line
		/*
		* entry_from_vm86.c - tests kernel entries from vm86 mode
		* Copyright (c) 2014-2015 Andrew Lutomirski
		*
		* This exercises a few paths that need to special-case vm86 mode.
		*
		* GPL v2.
		*/

		#define _GNU_SOURCE

		#include <assert.h>
		#include <stdlib.h>
		#include <sys/syscall.h>
		#include <sys/signal.h>
		#include <sys/ucontext.h>
		#include <unistd.h>
		#include <stdio.h>
		#include <string.h>
		#include <inttypes.h>
		#include <sys/mman.h>
		#include <err.h>
		#include <stddef.h>
		#include <stdbool.h>
		#include <errno.h>
		#include <sys/vm86.h>

		static unsigned long load_addr = 0x10000;
		static int nerrs = 0;

		asm (
		".pushsection .rodata\n\t"
		".type vmcode_bound, @object\n\t"
		"vmcode:\n\t"
		"vmcode_bound:\n\t"
		".code16\n\t"
		"bound %ax, (2048)\n\t"
		"int3\n\t"
		"vmcode_sysenter:\n\t"
		"sysenter\n\t"
		".size vmcode, . - vmcode\n\t"
		"end_vmcode:\n\t"
		".code32\n\t"
		".popsection"
		);

		extern unsigned char vmcode[], end_vmcode[];
		extern unsigned char vmcode_bound[], vmcode_sysenter[];

		static void do_test(struct vm86plus_struct *v86, unsigned long eip,
		const char *text)
		{
		long ret;

		printf("[RUN]\t%s from vm86 mode\n", text);
		v86->regs.eip = eip;
		ret = vm86(VM86_ENTER, v86);

		if (ret == -1 && errno == ENOSYS) {
		printf("[SKIP]\tvm86 not supported\n");
		return;
		}

		if (VM86_TYPE(ret) == VM86_INTx) {
		char trapname[32];
		int trapno = VM86_ARG(ret);
		if (trapno == 13)
		strcpy(trapname, "GP");
		else if (trapno == 5)
		strcpy(trapname, "BR");
		else if (trapno == 14)
		strcpy(trapname, "PF");
		else
		sprintf(trapname, "%d", trapno);

		printf("[OK]\tExited vm86 mode due to #%s\n", trapname);
		} else if (VM86_TYPE(ret) == VM86_UNKNOWN) {
		printf("[OK]\tExited vm86 mode due to unhandled GP fault\n");
		} else {
		printf("[OK]\tExited vm86 mode due to type %ld, arg %ld\n",
		VM86_TYPE(ret), VM86_ARG(ret));
		}
		}

		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;

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

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

		/* SYSENTER -- should cause #GP or #UD depending on CPU */
		do_test(&v86, vmcode_sysenter - vmcode, "SYSENTER");

		return (nerrs == 0 ? 0 : 1);
		}

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