Patch "x86/head: Add unwind hint annotations" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

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;a=summary

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.git.jpoimboe@redhat.com
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