This is a note to let you know that I've just added the patch titled

x86/head: Add unwind hint annotations

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-head-add-unwind-hint-annotations.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 2704fbb672d0d9a19414907fda7949283dcef6a1 Mon Sep 17 00:00:00 2001

From: Josh Poimboeuf jpoimboe@redhat.com Date: Mon, 18 Sep 2017 21:43:37 -0500 Subject: x86/head: Add unwind hint annotations

From: Josh Poimboeuf jpoimboe@redhat.com

commit 2704fbb672d0d9a19414907fda7949283dcef6a1 upstream.

Jiri Slaby reported an ORC issue when unwinding from an idle task. The stack was:

ffffffff811083c2 do_idle+0x142/0x1e0 ffffffff8110861d cpu_startup_entry+0x5d/0x60 ffffffff82715f58 start_kernel+0x3ff/0x407 ffffffff827153e8 x86_64_start_kernel+0x14e/0x15d ffffffff810001bf secondary_startup_64+0x9f/0xa0

The ORC unwinder errored out at secondary_startup_64 because the head code isn't annotated yet so there wasn't a corresponding ORC entry.

Fix that and any other head-related unwinding issues by adding unwind hints to the head code.

Reported-by: Jiri Slaby jslaby@suse.cz Tested-by: Jiri Slaby jslaby@suse.cz Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Cc: Andy Lutomirski luto@kernel.org Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: Juergen Gross jgross@suse.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/78ef000a2f68f545d6eef44ee912edceaad82ccf.1505764066... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kernel/Makefile | 1 - arch/x86/kernel/head_64.S | 14 ++++++++++++-- 2 files changed, 12 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -27,7 +27,6 @@ KASAN_SANITIZE_dumpstack.o := n KASAN_SANITIZE_dumpstack_$(BITS).o := n KASAN_SANITIZE_stacktrace.o := n

-OBJECT_FILES_NON_STANDARD_head_$(BITS).o := y OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y OBJECT_FILES_NON_STANDARD_test_nx.o := y --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -50,6 +50,7 @@ L3_START_KERNEL = pud_index(__START_KERN .code64 .globl startup_64 startup_64: + UNWIND_HINT_EMPTY /* * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, * and someone has loaded an identity mapped page table @@ -89,6 +90,7 @@ startup_64: addq $(early_top_pgt - __START_KERNEL_map), %rax jmp 1f ENTRY(secondary_startup_64) + UNWIND_HINT_EMPTY /* * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0, * and someone has loaded a mapped page table. @@ -133,6 +135,7 @@ ENTRY(secondary_startup_64) movq $1f, %rax jmp *%rax 1: + UNWIND_HINT_EMPTY

/* Check if nx is implemented */ movl $0x80000001, %eax @@ -247,6 +250,7 @@ END(secondary_startup_64) */ ENTRY(start_cpu0) movq initial_stack(%rip), %rsp + UNWIND_HINT_EMPTY jmp .Ljump_to_C_code ENDPROC(start_cpu0) #endif @@ -271,13 +275,18 @@ ENTRY(early_idt_handler_array) i = 0 .rept NUM_EXCEPTION_VECTORS .ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1 - pushq $0 # Dummy error code, to make stack frame uniform + UNWIND_HINT_IRET_REGS + pushq $0 # Dummy error code, to make stack frame uniform + .else + UNWIND_HINT_IRET_REGS offset=8 .endif pushq $i # 72(%rsp) Vector number jmp early_idt_handler_common + UNWIND_HINT_IRET_REGS i = i + 1 .fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc .endr + UNWIND_HINT_IRET_REGS offset=16 END(early_idt_handler_array)

early_idt_handler_common: @@ -306,6 +315,7 @@ early_idt_handler_common: pushq %r13 /* pt_regs->r13 */ pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ + UNWIND_HINT_REGS

cmpq $14,%rsi /* Page fault? */ jnz 10f @@ -428,7 +438,7 @@ ENTRY(phys_base) EXPORT_SYMBOL(phys_base)

#include "../../x86/xen/xen-head.S" - + __PAGE_ALIGNED_BSS NEXT_PAGE(empty_zero_page) .skip PAGE_SIZE

Patches currently in stable-queue which might be from jpoimboe@redhat.com are

queue-4.14/x86-asm-don-t-use-the-confusing-.ifeq-directive.patch queue-4.14/x86-boot-relocate-definition-of-the-initial-state-of-cr0.patch queue-4.14/objtool-don-t-report-end-of-section-error-after-an-empty-unwind-hint.patch queue-4.14/x86-xen-fix-xen-head-elf-annotations.patch queue-4.14/x86-head-fix-head-elf-function-annotations.patch queue-4.14/objtool-print-top-level-commands-on-incorrect-usage.patch queue-4.14/x86-unwind-rename-unwinder-config-options-to-config_unwinder_.patch queue-4.14/x86-head-add-unwind-hint-annotations.patch queue-4.14/x86-head-remove-unused-bad_address-code.patch queue-4.14/x86-xen-add-unwind-hint-annotations.patch queue-4.14/x86-head-remove-confusing-comment.patch queue-4.14/x86-unwinder-make-config_unwinder_orc-y-the-default-in-the-64-bit-defconfig.patch queue-4.14/x86-unwind-make-config_unwinder_orc-y-the-default-in-kconfig-for-64-bit.patch queue-4.14/x86-mm-relocate-page-fault-error-codes-to-traps.h.patch queue-4.14/x86-boot-annotate-verify_cpu-as-a-callable-function.patch