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Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 page table isolation fixes from Thomas Gleixner:
 "A couple of urgent fixes for PTI:

   - Fix a PTE mismatch between user and kernel visible mapping of the
     cpu entry area (differs vs. the GLB bit) and causes a TLB mismatch
     MCE on older AMD K8 machines

   - Fix the misplaced CR3 switch in the SYSCALL compat entry code which
     causes access to unmapped kernel memory resulting in double faults.

   - Fix the section mismatch of the cpu_tss_rw percpu storage caused by
     using a different mechanism for declaration and definition.

   - Two fixes for dumpstack which help to decode entry stack issues
     better

   - Enable PTI by default in Kconfig. We should have done that earlier,
     but it slipped through the cracks.

   - Exclude AMD from the PTI enforcement. Not necessarily a fix, but if
     AMD is so confident that they are not affected, then we should not
     burden users with the overhead"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/process: Define cpu_tss_rw in same section as declaration
  x86/pti: Switch to kernel CR3 at early in entry_SYSCALL_compat()
  x86/dumpstack: Print registers for first stack frame
  x86/dumpstack: Fix partial register dumps
  x86/pti: Make sure the user/kernel PTEs match
  x86/cpu, x86/pti: Do not enable PTI on AMD processors
  x86/pti: Enable PTI by default
hifive-unleashed-5.1
Linus Torvalds 2018-01-03 16:41:07 -08:00
parent d6bbd51587 2fd9c41aea
commit 00a5ae218d
8 changed files with 48 additions and 25 deletions
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13
arch/x86/entry/entry_64_compat.S
View File

@ -190,8 +190,13 @@ ENTRY(entry_SYSCALL_compat)
/* Interrupts are off on entry. */
swapgs
/* Stash user ESP and switch to the kernel stack. */
/* Stash user ESP */
movl %esp, %r8d
/* Use %rsp as scratch reg. User ESP is stashed in r8 */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp
/* Switch to the kernel stack */
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
/* Construct struct pt_regs on stack */
@ -219,12 +224,6 @@ GLOBAL(entry_SYSCALL_compat_after_hwframe)
pushq $0 /* pt_regs->r14 = 0 */
pushq $0 /* pt_regs->r15 = 0 */
/*
* We just saved %rdi so it is safe to clobber. It is not
* preserved during the C calls inside TRACE_IRQS_OFF anyway.
*/
SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi
/*
* User mode is traced as though IRQs are on, and SYSENTER
* turned them off.

17
arch/x86/include/asm/unwind.h
View File

@ -56,18 +56,27 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
#if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER)
/*
* WARNING: The entire pt_regs may not be safe to dereference. In some cases,
* only the iret frame registers are accessible. Use with caution!
* If 'partial' returns true, only the iret frame registers are valid.
*/
static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
bool *partial)
{
if (unwind_done(state))
return NULL;
if (partial) {
#ifdef CONFIG_UNWINDER_ORC
*partial = !state->full_regs;
#else
*partial = false;
#endif
}
return state->regs;
}
#else
static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
bool *partial)
{
return NULL;
}

4
arch/x86/kernel/cpu/common.c
View File

@ -923,8 +923,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
setup_force_cpu_cap(X86_FEATURE_ALWAYS);
/* Assume for now that ALL x86 CPUs are insecure */
setup_force_cpu_bug(X86_BUG_CPU_INSECURE);
if (c->x86_vendor != X86_VENDOR_AMD)
setup_force_cpu_bug(X86_BUG_CPU_INSECURE);
fpu__init_system(c);

31
arch/x86/kernel/dumpstack.c
View File

@ -76,12 +76,23 @@ void show_iret_regs(struct pt_regs *regs)
regs->sp, regs->flags);
}
static void show_regs_safe(struct stack_info *info, struct pt_regs *regs)
static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
bool partial)
{
if (on_stack(info, regs, sizeof(*regs)))
/*
* These on_stack() checks aren't strictly necessary: the unwind code
* has already validated the 'regs' pointer. The checks are done for
* ordering reasons: if the registers are on the next stack, we don't
* want to print them out yet. Otherwise they'll be shown as part of
* the wrong stack. Later, when show_trace_log_lvl() switches to the
* next stack, this function will be called again with the same regs so
* they can be printed in the right context.
*/
if (!partial && on_stack(info, regs, sizeof(*regs))) {
__show_regs(regs, 0);
else if (on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
IRET_FRAME_SIZE)) {
} else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
IRET_FRAME_SIZE)) {
/*
* When an interrupt or exception occurs in entry code, the
* full pt_regs might not have been saved yet. In that case
@ -98,11 +109,13 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
struct stack_info stack_info = {0};
unsigned long visit_mask = 0;
int graph_idx = 0;
bool partial;
printk("%sCall Trace:\n", log_lvl);
unwind_start(&state, task, regs, stack);
stack = stack ? : get_stack_pointer(task, regs);
regs = unwind_get_entry_regs(&state, &partial);
/*
* Iterate through the stacks, starting with the current stack pointer.
@ -120,7 +133,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
* - hardirq stack
* - entry stack
*/
for (regs = NULL; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
const char *stack_name;
if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
@ -140,7 +153,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
printk("%s <%s>\n", log_lvl, stack_name);
if (regs)
show_regs_safe(&stack_info, regs);
show_regs_if_on_stack(&stack_info, regs, partial);
/*
* Scan the stack, printing any text addresses we find. At the
@ -164,7 +177,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
/*
* Don't print regs->ip again if it was already printed
* by show_regs_safe() below.
* by show_regs_if_on_stack().
*/
if (regs && stack == &regs->ip)
goto next;
@ -199,9 +212,9 @@ next:
unwind_next_frame(&state);
/* if the frame has entry regs, print them */
regs = unwind_get_entry_regs(&state);
regs = unwind_get_entry_regs(&state, &partial);
if (regs)
show_regs_safe(&stack_info, regs);
show_regs_if_on_stack(&stack_info, regs, partial);
}
if (stack_name)

2
arch/x86/kernel/process.c
View File

@ -47,7 +47,7 @@
* section. Since TSS's are completely CPU-local, we want them
* on exact cacheline boundaries, to eliminate cacheline ping-pong.
*/
__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss_rw) = {
__visible DEFINE_PER_CPU_PAGE_ALIGNED(struct tss_struct, cpu_tss_rw) = {
.x86_tss = {
/*
* .sp0 is only used when entering ring 0 from a lower

2
arch/x86/kernel/stacktrace.c
View File

@ -102,7 +102,7 @@ __save_stack_trace_reliable(struct stack_trace *trace,
for (unwind_start(&state, task, NULL, NULL); !unwind_done(&state);
unwind_next_frame(&state)) {
regs = unwind_get_entry_regs(&state);
regs = unwind_get_entry_regs(&state, NULL);
if (regs) {
/*
* Kernel mode registers on the stack indicate an

3
arch/x86/mm/pti.c
View File

@ -367,7 +367,8 @@ static void __init pti_setup_espfix64(void)
static void __init pti_clone_entry_text(void)
{
pti_clone_pmds((unsigned long) __entry_text_start,
(unsigned long) __irqentry_text_end, _PAGE_RW);
(unsigned long) __irqentry_text_end,
_PAGE_RW | _PAGE_GLOBAL);
}
/*

1
security/Kconfig
View File

@ -56,6 +56,7 @@ config SECURITY_NETWORK
config PAGE_TABLE_ISOLATION
bool "Remove the kernel mapping in user mode"
default y
depends on X86_64 && !UML
help
This feature reduces the number of hardware side channels by