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

Pull x86 fixes from Thomas Gleixner:
 "A set of fixes for x86:

   - Make the unwinder more robust when it encounters a NULL pointer
     call, so the backtrace becomes more useful

   - Fix the bogus ORC unwind table alignment

   - Prevent kernel panic during kexec on HyperV caused by a cleared but
     not disabled hypercall page.

   - Remove the now pointless stacksize increase for KASAN_EXTRA, as
     KASAN_EXTRA is gone.

   - Remove unused variables from the x86 memory management code"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/hyperv: Fix kernel panic when kexec on HyperV
  x86/mm: Remove unused variable 'old_pte'
  x86/mm: Remove unused variable 'cpu'
  Revert "x86_64: Increase stack size for KASAN_EXTRA"
  x86/unwind: Add hardcoded ORC entry for NULL
  x86/unwind: Handle NULL pointer calls better in frame unwinder
  x86/unwind/orc: Fix ORC unwind table alignment
This commit is contained in:
Linus Torvalds 2019-03-10 14:46:56 -07:00
commit 262d6a9a63
7 changed files with 55 additions and 10 deletions

View File

@ -407,6 +407,13 @@ void hyperv_cleanup(void)
/* Reset our OS id */
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
/*
* Reset hypercall page reference before reset the page,
* let hypercall operations fail safely rather than
* panic the kernel for using invalid hypercall page
*/
hv_hypercall_pg = NULL;
/* Reset the hypercall page */
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

View File

@ -7,11 +7,7 @@
#endif
#ifdef CONFIG_KASAN
#ifdef CONFIG_KASAN_EXTRA
#define KASAN_STACK_ORDER 2
#else
#define KASAN_STACK_ORDER 1
#endif
#else
#define KASAN_STACK_ORDER 0
#endif

View File

@ -23,6 +23,12 @@ struct unwind_state {
#elif defined(CONFIG_UNWINDER_FRAME_POINTER)
bool got_irq;
unsigned long *bp, *orig_sp, ip;
/*
* If non-NULL: The current frame is incomplete and doesn't contain a
* valid BP. When looking for the next frame, use this instead of the
* non-existent saved BP.
*/
unsigned long *next_bp;
struct pt_regs *regs;
#else
unsigned long *sp;

View File

@ -320,10 +320,14 @@ bool unwind_next_frame(struct unwind_state *state)
}
/* Get the next frame pointer: */
if (state->regs)
if (state->next_bp) {
next_bp = state->next_bp;
state->next_bp = NULL;
} else if (state->regs) {
next_bp = (unsigned long *)state->regs->bp;
else
} else {
next_bp = (unsigned long *)READ_ONCE_TASK_STACK(state->task, *state->bp);
}
/* Move to the next frame if it's safe: */
if (!update_stack_state(state, next_bp))
@ -398,6 +402,21 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
bp = get_frame_pointer(task, regs);
/*
* If we crash with IP==0, the last successfully executed instruction
* was probably an indirect function call with a NULL function pointer.
* That means that SP points into the middle of an incomplete frame:
* *SP is a return pointer, and *(SP-sizeof(unsigned long)) is where we
* would have written a frame pointer if we hadn't crashed.
* Pretend that the frame is complete and that BP points to it, but save
* the real BP so that we can use it when looking for the next frame.
*/
if (regs && regs->ip == 0 &&
(unsigned long *)kernel_stack_pointer(regs) >= first_frame) {
state->next_bp = bp;
bp = ((unsigned long *)kernel_stack_pointer(regs)) - 1;
}
/* Initialize stack info and make sure the frame data is accessible: */
get_stack_info(bp, state->task, &state->stack_info,
&state->stack_mask);
@ -410,7 +429,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
*/
while (!unwind_done(state) &&
(!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
state->bp < first_frame))
(state->next_bp == NULL && state->bp < first_frame)))
unwind_next_frame(state);
}
EXPORT_SYMBOL_GPL(__unwind_start);

View File

@ -113,6 +113,20 @@ static struct orc_entry *orc_ftrace_find(unsigned long ip)
}
#endif
/*
* If we crash with IP==0, the last successfully executed instruction
* was probably an indirect function call with a NULL function pointer,
* and we don't have unwind information for NULL.
* This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function
* pointer into its parent and then continue normally from there.
*/
static struct orc_entry null_orc_entry = {
.sp_offset = sizeof(long),
.sp_reg = ORC_REG_SP,
.bp_reg = ORC_REG_UNDEFINED,
.type = ORC_TYPE_CALL
};
static struct orc_entry *orc_find(unsigned long ip)
{
static struct orc_entry *orc;
@ -120,6 +134,9 @@ static struct orc_entry *orc_find(unsigned long ip)
if (!orc_init)
return NULL;
if (ip == 0)
return &null_orc_entry;
/* For non-init vmlinux addresses, use the fast lookup table: */
if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
unsigned int idx, start, stop;

View File

@ -738,7 +738,7 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address,
{
unsigned long numpages, pmask, psize, lpaddr, pfn, old_pfn;
pgprot_t old_prot, new_prot, req_prot, chk_prot;
pte_t new_pte, old_pte, *tmp;
pte_t new_pte, *tmp;
enum pg_level level;
/*
@ -781,7 +781,7 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address,
* Convert protection attributes to 4k-format, as cpa->mask* are set
* up accordingly.
*/
old_pte = *kpte;
/* Clear PSE (aka _PAGE_PAT) and move PAT bit to correct position */
req_prot = pgprot_large_2_4k(old_prot);

View File

@ -733,7 +733,7 @@
KEEP(*(.orc_unwind_ip)) \
__stop_orc_unwind_ip = .; \
} \
. = ALIGN(6); \
. = ALIGN(2); \
.orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \
__start_orc_unwind = .; \
KEEP(*(.orc_unwind)) \