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Date: Mon, 1 Jun 2015 22:37:15 -0700
From: tip-bot for Andy Lutomirski <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: peterz@...radead.org, luto@...nel.org,
linux-kernel@...r.kernel.org, mingo@...nel.org,
shuahkh@....samsung.com, JBeulich@...e.com, tglx@...utronix.de,
hpa@...or.com, torvalds@...ux-foundation.org
Subject: [tip:x86/urgent] x86/asm/entry/32, selftests:
Add a selftest for kernel entries from VM86 mode
Commit-ID: c2affbf9a50882572e04645d5946ab0a921f061f
Gitweb: http://git.kernel.org/tip/c2affbf9a50882572e04645d5946ab0a921f061f
Author: Andy Lutomirski <luto@...nel.org>
AuthorDate: Fri, 29 May 2015 14:58:24 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 30 May 2015 10:21:32 +0200
x86/asm/entry/32, selftests: Add a selftest for kernel entries from VM86 mode
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@...nel.org>
Cc: Jan Beulich <JBeulich@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Shuah Khan <shuahkh@....samsung.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/09a9916761e0a9e42d4922f147af45a0079cc1e8.1432936374.git.luto@kernel.org
Tests: 394838c96013 x86/asm/entry/32: Fix user_mode() misuses
Tests: 7ba554b5ac69 x86/asm/entry/32: Really make user_mode() work correctly for VM86 mode
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
tools/testing/selftests/x86/Makefile | 6 +-
tools/testing/selftests/x86/entry_from_vm86.c | 114 ++++++++++++++++++++++++++
2 files changed, 118 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 5bdb781..9b0d8ba 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -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
diff --git a/tools/testing/selftests/x86/entry_from_vm86.c b/tools/testing/selftests/x86/entry_from_vm86.c
new file mode 100644
index 0000000..5c38a18
--- /dev/null
+++ b/tools/testing/selftests/x86/entry_from_vm86.c
@@ -0,0 +1,114 @@
+/*
+ * 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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