Linus,
please pull the latest x86-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
x86-urgent-for-linus
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.
Thanks,
tglx
------------------>
Jann Horn (2):
x86/unwind: Handle NULL pointer calls better in frame unwinder
x86/unwind: Add hardcoded ORC entry for NULL
Josh Poimboeuf (1):
x86/unwind/orc: Fix ORC unwind table alignment
Kairui Song (1):
x86/hyperv: Fix kernel panic when kexec on HyperV
Qian Cai (3):
Revert "x86_64: Increase stack size for KASAN_EXTRA"
x86/mm: Remove unused variable 'cpu'
x86/mm: Remove unused variable 'old_pte'
arch/x86/hyperv/hv_init.c | 7 +++++++
arch/x86/include/asm/page_64_types.h | 4 ----
arch/x86/include/asm/unwind.h | 6 ++++++
arch/x86/kernel/unwind_frame.c | 25 ++++++++++++++++++++++---
arch/x86/kernel/unwind_orc.c | 17 +++++++++++++++++
arch/x86/mm/pageattr.c | 4 ++--
arch/x86/mm/tlb.c | 3 ---
include/asm-generic/vmlinux.lds.h | 2 +-
8 files changed, 55 insertions(+), 13 deletions(-)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 7abb09e2eeb8..d3f42b6bbdac 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -406,6 +406,13 @@ 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);
diff --git a/arch/x86/include/asm/page_64_types.h
b/arch/x86/include/asm/page_64_types.h
index 0ce558a8150d..8f657286d599 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -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
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 1f86e1b0a5cd..499578f7e6d7 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -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;
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 3dc26f95d46e..9b9fd4826e7a 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -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);
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 26038eacf74a..89be1be1790c 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -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;
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 14e6119838a6..4c570612e24e 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -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);
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 999d6d8f0bef..bc4bc7b2f075 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -685,9 +685,6 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
* that UV should be updated so that smp_call_function_many(),
* etc, are optimal on UV.
*/
- unsigned int cpu;
-
- cpu = smp_processor_id();
cpumask = uv_flush_tlb_others(cpumask, info);
if (cpumask)
smp_call_function_many(cpumask, flush_tlb_func_remote,
diff --git a/include/asm-generic/vmlinux.lds.h
b/include/asm-generic/vmlinux.lds.h
index 3d7a6a9c2370..f8f6f04c4453 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -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)) \
