From 2704fbb672d0d9a19414907fda7949283dcef6a1 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 18 Sep 2017 21:43:37 -0500 Subject: [PATCH] x86/head: Add unwind hint annotations 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 Tested-by: Jiri Slaby Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/78ef000a2f68f545d6eef44ee912edceaad82ccf.1505764066.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/Makefile | 1 - arch/x86/kernel/head_64.S | 14 ++++++++++++-- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index fd0a789..d8e2b70 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -26,7 +26,6 @@ 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 diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index edacd57..42e32c2 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -49,6 +49,7 @@ L3_START_KERNEL = pud_index(__START_KERNEL_map) .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 @@ -88,6 +89,7 @@ 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. @@ -132,6 +134,7 @@ ENTRY(secondary_startup_64) movq $1f, %rax jmp *%rax 1: + UNWIND_HINT_EMPTY /* Check if nx is implemented */ movl $0x80000001, %eax @@ -246,6 +249,7 @@ END(secondary_startup_64) */ ENTRY(start_cpu0) movq initial_stack(%rip), %rsp + UNWIND_HINT_EMPTY jmp .Ljump_to_C_code ENDPROC(start_cpu0) #endif @@ -270,13 +274,18 @@ 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: @@ -305,6 +314,7 @@ 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 @@ -427,7 +437,7 @@ ENTRY(phys_base) EXPORT_SYMBOL(phys_base) #include "../../x86/xen/xen-head.S" - + __PAGE_ALIGNED_BSS NEXT_PAGE(empty_zero_page) .skip PAGE_SIZE -- 2.7.4