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authorLinus Torvalds <torvalds@linux-foundation.org>2011-08-12 20:46:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-08-12 20:46:24 -0700
commit06e727d2a5d9d889fabad35223ad77205a9bebb9 (patch)
tree2a2d4ec9ed95c95f044c8d69e87ab47195a1d2ed /arch/x86/kernel
parente68ff9cd15552e46e0f993eace25af0947b1222d (diff)
parent3ae36655b97a03fa1decf72f04078ef945647c1a (diff)
Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip: x86-64: Rework vsyscall emulation and add vsyscall= parameter x86-64: Wire up getcpu syscall x86: Remove unnecessary compile flag tweaks for vsyscall code x86-64: Add vsyscall:emulate_vsyscall trace event x86-64: Add user_64bit_mode paravirt op x86-64, xen: Enable the vvar mapping x86-64: Work around gold bug 13023 x86-64: Move the "user" vsyscall segment out of the data segment. x86-64: Pad vDSO to a page boundary
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/Makefile13
-rw-r--r--arch/x86/kernel/entry_64.S1
-rw-r--r--arch/x86/kernel/paravirt.c4
-rw-r--r--arch/x86/kernel/step.c2
-rw-r--r--arch/x86/kernel/traps.c6
-rw-r--r--arch/x86/kernel/vmlinux.lds.S41
-rw-r--r--arch/x86/kernel/vsyscall_64.c90
-rw-r--r--arch/x86/kernel/vsyscall_emu_64.S36
-rw-r--r--arch/x86/kernel/vsyscall_trace.h29
9 files changed, 117 insertions, 105 deletions
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 04105574c8e9..82f2912155a5 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -17,19 +17,6 @@ CFLAGS_REMOVE_ftrace.o = -pg
CFLAGS_REMOVE_early_printk.o = -pg
endif
-#
-# vsyscalls (which work on the user stack) should have
-# no stack-protector checks:
-#
-nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp)
-CFLAGS_hpet.o := $(nostackp)
-CFLAGS_paravirt.o := $(nostackp)
-GCOV_PROFILE_vsyscall_64.o := n
-GCOV_PROFILE_hpet.o := n
-GCOV_PROFILE_tsc.o := n
-GCOV_PROFILE_paravirt.o := n
-
obj-y := process_$(BITS).o signal.o entry_$(BITS).o
obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
obj-y += time.o ioport.o ldt.o dumpstack.o
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index e13329d800c8..6419bb05ecd5 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1111,7 +1111,6 @@ zeroentry spurious_interrupt_bug do_spurious_interrupt_bug
zeroentry coprocessor_error do_coprocessor_error
errorentry alignment_check do_alignment_check
zeroentry simd_coprocessor_error do_simd_coprocessor_error
-zeroentry emulate_vsyscall do_emulate_vsyscall
/* Reload gs selector with exception handling */
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 613a7931ecc1..d90272e6bc40 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -307,6 +307,10 @@ struct pv_info pv_info = {
.paravirt_enabled = 0,
.kernel_rpl = 0,
.shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
+
+#ifdef CONFIG_X86_64
+ .extra_user_64bit_cs = __USER_CS,
+#endif
};
struct pv_init_ops pv_init_ops = {
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 7977f0cfe339..c346d1161488 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -74,7 +74,7 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
#ifdef CONFIG_X86_64
case 0x40 ... 0x4f:
- if (regs->cs != __USER_CS)
+ if (!user_64bit_mode(regs))
/* 32-bit mode: register increment */
return 0;
/* 64-bit mode: REX prefix */
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 9682ec50180c..6913369c234c 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -872,12 +872,6 @@ void __init trap_init(void)
set_bit(SYSCALL_VECTOR, used_vectors);
#endif
-#ifdef CONFIG_X86_64
- BUG_ON(test_bit(VSYSCALL_EMU_VECTOR, used_vectors));
- set_system_intr_gate(VSYSCALL_EMU_VECTOR, &emulate_vsyscall);
- set_bit(VSYSCALL_EMU_VECTOR, used_vectors);
-#endif
-
/*
* Should be a barrier for any external CPU state:
*/
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 4aa9c54a9b76..0f703f10901a 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -71,7 +71,6 @@ PHDRS {
text PT_LOAD FLAGS(5); /* R_E */
data PT_LOAD FLAGS(6); /* RW_ */
#ifdef CONFIG_X86_64
- user PT_LOAD FLAGS(5); /* R_E */
#ifdef CONFIG_SMP
percpu PT_LOAD FLAGS(6); /* RW_ */
#endif
@@ -154,44 +153,16 @@ SECTIONS
#ifdef CONFIG_X86_64
-#define VSYSCALL_ADDR (-10*1024*1024)
-
-#define VLOAD_OFFSET (VSYSCALL_ADDR - __vsyscall_0 + LOAD_OFFSET)
-#define VLOAD(x) (ADDR(x) - VLOAD_OFFSET)
-
-#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0)
-#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
-
- . = ALIGN(4096);
- __vsyscall_0 = .;
-
- . = VSYSCALL_ADDR;
- .vsyscall : AT(VLOAD(.vsyscall)) {
- *(.vsyscall_0)
-
- . = 1024;
- *(.vsyscall_1)
-
- . = 2048;
- *(.vsyscall_2)
-
- . = 4096; /* Pad the whole page. */
- } :user =0xcc
- . = ALIGN(__vsyscall_0 + PAGE_SIZE, PAGE_SIZE);
-
-#undef VSYSCALL_ADDR
-#undef VLOAD_OFFSET
-#undef VLOAD
-#undef VVIRT_OFFSET
-#undef VVIRT
-
+ . = ALIGN(PAGE_SIZE);
__vvar_page = .;
.vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
+ /* work around gold bug 13023 */
+ __vvar_beginning_hack = .;
- /* Place all vvars at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) \
- . = offset; \
+ /* Place all vvars at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) \
+ . = __vvar_beginning_hack + offset; \
*(.vvar_ ## name)
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index dda7dff9cef7..18ae83dd1cd7 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -18,9 +18,6 @@
* use the vDSO.
*/
-/* Disable profiling for userspace code: */
-#define DISABLE_BRANCH_PROFILING
-
#include <linux/time.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -50,12 +47,36 @@
#include <asm/vgtod.h>
#include <asm/traps.h>
+#define CREATE_TRACE_POINTS
+#include "vsyscall_trace.h"
+
DEFINE_VVAR(int, vgetcpu_mode);
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
{
.lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
};
+static enum { EMULATE, NATIVE, NONE } vsyscall_mode = EMULATE;
+
+static int __init vsyscall_setup(char *str)
+{
+ if (str) {
+ if (!strcmp("emulate", str))
+ vsyscall_mode = EMULATE;
+ else if (!strcmp("native", str))
+ vsyscall_mode = NATIVE;
+ else if (!strcmp("none", str))
+ vsyscall_mode = NONE;
+ else
+ return -EINVAL;
+
+ return 0;
+ }
+
+ return -EINVAL;
+}
+early_param("vsyscall", vsyscall_setup);
+
void update_vsyscall_tz(void)
{
unsigned long flags;
@@ -100,7 +121,7 @@ static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
printk("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",
level, tsk->comm, task_pid_nr(tsk),
- message, regs->ip - 2, regs->cs,
+ message, regs->ip, regs->cs,
regs->sp, regs->ax, regs->si, regs->di);
}
@@ -118,46 +139,39 @@ static int addr_to_vsyscall_nr(unsigned long addr)
return nr;
}
-void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
+bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
{
struct task_struct *tsk;
unsigned long caller;
int vsyscall_nr;
long ret;
- local_irq_enable();
-
/*
- * Real 64-bit user mode code has cs == __USER_CS. Anything else
- * is bogus.
+ * No point in checking CS -- the only way to get here is a user mode
+ * trap to a high address, which means that we're in 64-bit user code.
*/
- if (regs->cs != __USER_CS) {
- /*
- * If we trapped from kernel mode, we might as well OOPS now
- * instead of returning to some random address and OOPSing
- * then.
- */
- BUG_ON(!user_mode(regs));
- /* Compat mode and non-compat 32-bit CS should both segfault. */
- warn_bad_vsyscall(KERN_WARNING, regs,
- "illegal int 0xcc from 32-bit mode");
- goto sigsegv;
+ WARN_ON_ONCE(address != regs->ip);
+
+ if (vsyscall_mode == NONE) {
+ warn_bad_vsyscall(KERN_INFO, regs,
+ "vsyscall attempted with vsyscall=none");
+ return false;
}
- /*
- * x86-ism here: regs->ip points to the instruction after the int 0xcc,
- * and int 0xcc is two bytes long.
- */
- vsyscall_nr = addr_to_vsyscall_nr(regs->ip - 2);
+ vsyscall_nr = addr_to_vsyscall_nr(address);
+
+ trace_emulate_vsyscall(vsyscall_nr);
+
if (vsyscall_nr < 0) {
warn_bad_vsyscall(KERN_WARNING, regs,
- "illegal int 0xcc (exploit attempt?)");
+ "misaligned vsyscall (exploit attempt or buggy program) -- look up the vsyscall kernel parameter if you need a workaround");
goto sigsegv;
}
if (get_user(caller, (unsigned long __user *)regs->sp) != 0) {
- warn_bad_vsyscall(KERN_WARNING, regs, "int 0xcc with bad stack (exploit attempt?)");
+ warn_bad_vsyscall(KERN_WARNING, regs,
+ "vsyscall with bad stack (exploit attempt?)");
goto sigsegv;
}
@@ -202,13 +216,11 @@ void dotraplinkage do_emulate_vsyscall(struct pt_regs *regs, long error_code)
regs->ip = caller;
regs->sp += 8;
- local_irq_disable();
- return;
+ return true;
sigsegv:
- regs->ip -= 2; /* The faulting instruction should be the int 0xcc. */
force_sig(SIGSEGV, current);
- local_irq_disable();
+ return true;
}
/*
@@ -256,15 +268,21 @@ cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
void __init map_vsyscall(void)
{
- extern char __vsyscall_0;
- unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+ extern char __vsyscall_page;
+ unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page);
extern char __vvar_page;
unsigned long physaddr_vvar_page = __pa_symbol(&__vvar_page);
- /* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
- __set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
+ __set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_vsyscall,
+ vsyscall_mode == NATIVE
+ ? PAGE_KERNEL_VSYSCALL
+ : PAGE_KERNEL_VVAR);
+ BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_FIRST_PAGE) !=
+ (unsigned long)VSYSCALL_START);
+
__set_fixmap(VVAR_PAGE, physaddr_vvar_page, PAGE_KERNEL_VVAR);
- BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) != (unsigned long)VVAR_ADDRESS);
+ BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) !=
+ (unsigned long)VVAR_ADDRESS);
}
static int __init vsyscall_init(void)
diff --git a/arch/x86/kernel/vsyscall_emu_64.S b/arch/x86/kernel/vsyscall_emu_64.S
index ffa845eae5ca..c9596a9af159 100644
--- a/arch/x86/kernel/vsyscall_emu_64.S
+++ b/arch/x86/kernel/vsyscall_emu_64.S
@@ -7,21 +7,31 @@
*/
#include <linux/linkage.h>
+
#include <asm/irq_vectors.h>
+#include <asm/page_types.h>
+#include <asm/unistd_64.h>
+
+__PAGE_ALIGNED_DATA
+ .globl __vsyscall_page
+ .balign PAGE_SIZE, 0xcc
+ .type __vsyscall_page, @object
+__vsyscall_page:
+
+ mov $__NR_gettimeofday, %rax
+ syscall
+ ret
-/* The unused parts of the page are filled with 0xcc by the linker script. */
+ .balign 1024, 0xcc
+ mov $__NR_time, %rax
+ syscall
+ ret
-.section .vsyscall_0, "a"
-ENTRY(vsyscall_0)
- int $VSYSCALL_EMU_VECTOR
-END(vsyscall_0)
+ .balign 1024, 0xcc
+ mov $__NR_getcpu, %rax
+ syscall
+ ret
-.section .vsyscall_1, "a"
-ENTRY(vsyscall_1)
- int $VSYSCALL_EMU_VECTOR
-END(vsyscall_1)
+ .balign 4096, 0xcc
-.section .vsyscall_2, "a"
-ENTRY(vsyscall_2)
- int $VSYSCALL_EMU_VECTOR
-END(vsyscall_2)
+ .size __vsyscall_page, 4096
diff --git a/arch/x86/kernel/vsyscall_trace.h b/arch/x86/kernel/vsyscall_trace.h
new file mode 100644
index 000000000000..a8b2edec54fe
--- /dev/null
+++ b/arch/x86/kernel/vsyscall_trace.h
@@ -0,0 +1,29 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vsyscall
+
+#if !defined(__VSYSCALL_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __VSYSCALL_TRACE_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(emulate_vsyscall,
+
+ TP_PROTO(int nr),
+
+ TP_ARGS(nr),
+
+ TP_STRUCT__entry(__field(int, nr)),
+
+ TP_fast_assign(
+ __entry->nr = nr;
+ ),
+
+ TP_printk("nr = %d", __entry->nr)
+);
+
+#endif
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ../../arch/x86/kernel
+#define TRACE_INCLUDE_FILE vsyscall_trace
+#include <trace/define_trace.h>

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