c2affbf9a5
Test a couple of special cases in 32-bit kernels for entries from vm86 mode. This will OOPS both old kernels due to a bug and and 4.1-rc5 due to a regression I introduced, and it should make sure that the SYSENTER-from-vm86-mode hack in the kernel keeps working. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Jan Beulich <JBeulich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/09a9916761e0a9e42d4922f147af45a0079cc1e8.1432936374.git.luto@kernel.org Tests:394838c960x86/asm/entry/32: Fix user_mode() misuses Tests:7ba554b5acx86/asm/entry/32: Really make user_mode() work correctly for VM86 mode Signed-off-by: Ingo Molnar <mingo@kernel.org>
114 lines
2.6 KiB
C
114 lines
2.6 KiB
C
/*
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* entry_from_vm86.c - tests kernel entries from vm86 mode
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* Copyright (c) 2014-2015 Andrew Lutomirski
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*
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* This exercises a few paths that need to special-case vm86 mode.
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*
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* GPL v2.
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*/
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#define _GNU_SOURCE
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#include <assert.h>
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#include <stdlib.h>
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#include <sys/syscall.h>
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#include <sys/signal.h>
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#include <sys/ucontext.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include <inttypes.h>
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#include <sys/mman.h>
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#include <err.h>
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#include <stddef.h>
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#include <stdbool.h>
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#include <errno.h>
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#include <sys/vm86.h>
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static unsigned long load_addr = 0x10000;
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static int nerrs = 0;
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asm (
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".pushsection .rodata\n\t"
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".type vmcode_bound, @object\n\t"
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"vmcode:\n\t"
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"vmcode_bound:\n\t"
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".code16\n\t"
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"bound %ax, (2048)\n\t"
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"int3\n\t"
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"vmcode_sysenter:\n\t"
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"sysenter\n\t"
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".size vmcode, . - vmcode\n\t"
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"end_vmcode:\n\t"
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".code32\n\t"
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".popsection"
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);
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extern unsigned char vmcode[], end_vmcode[];
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extern unsigned char vmcode_bound[], vmcode_sysenter[];
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static void do_test(struct vm86plus_struct *v86, unsigned long eip,
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const char *text)
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{
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long ret;
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printf("[RUN]\t%s from vm86 mode\n", text);
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v86->regs.eip = eip;
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ret = vm86(VM86_ENTER, v86);
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if (ret == -1 && errno == ENOSYS) {
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printf("[SKIP]\tvm86 not supported\n");
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return;
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}
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if (VM86_TYPE(ret) == VM86_INTx) {
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char trapname[32];
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int trapno = VM86_ARG(ret);
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if (trapno == 13)
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strcpy(trapname, "GP");
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else if (trapno == 5)
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strcpy(trapname, "BR");
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else if (trapno == 14)
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strcpy(trapname, "PF");
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else
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sprintf(trapname, "%d", trapno);
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printf("[OK]\tExited vm86 mode due to #%s\n", trapname);
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} else if (VM86_TYPE(ret) == VM86_UNKNOWN) {
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printf("[OK]\tExited vm86 mode due to unhandled GP fault\n");
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} else {
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printf("[OK]\tExited vm86 mode due to type %ld, arg %ld\n",
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VM86_TYPE(ret), VM86_ARG(ret));
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}
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}
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int main(void)
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{
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struct vm86plus_struct v86;
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unsigned char *addr = mmap((void *)load_addr, 4096,
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PROT_READ | PROT_WRITE | PROT_EXEC,
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MAP_ANONYMOUS | MAP_PRIVATE, -1,0);
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if (addr != (unsigned char *)load_addr)
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err(1, "mmap");
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memcpy(addr, vmcode, end_vmcode - vmcode);
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addr[2048] = 2;
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addr[2050] = 3;
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memset(&v86, 0, sizeof(v86));
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v86.regs.cs = load_addr / 16;
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v86.regs.ss = load_addr / 16;
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v86.regs.ds = load_addr / 16;
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v86.regs.es = load_addr / 16;
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assert((v86.regs.cs & 3) == 0); /* Looks like RPL = 0 */
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/* #BR -- should deliver SIG??? */
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do_test(&v86, vmcode_bound - vmcode, "#BR");
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/* SYSENTER -- should cause #GP or #UD depending on CPU */
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do_test(&v86, vmcode_sysenter - vmcode, "SYSENTER");
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return (nerrs == 0 ? 0 : 1);
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}
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