x86/xen: Support objtool validation in xen-asm.S

The OBJECT_FILES_NON_STANDARD annotation is used to tell objtool to
ignore a file.  File-level ignores won't work when validating vmlinux.o.

Tweak the ELF metadata and unwind hints to allow objtool to follow the
code.

Cc: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8b042a09c69e8645f3b133ef6653ba28f896807d.1611263462.git.jpoimboe@redhat.com

diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index fc5c5ba..40b5779 100644 (file)
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-OBJECT_FILES_NON_STANDARD_xen-asm.o := y
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not profile debug and lowlevel utilities

diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 1cb0e84..a05e80b 100644 (file)
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -14,6 +14,7 @@
 #include <asm/thread_info.h>
 #include <asm/asm.h>
 #include <asm/frame.h>
+#include <asm/unwind_hints.h>
 
 #include <xen/interface/xen.h>
 
@@ -146,6 +147,7 @@ SYM_FUNC_END(xen_read_cr2_direct);
 
 .macro xen_pv_trap name
 SYM_CODE_START(xen_\name)
+       UNWIND_HINT_EMPTY
        pop %rcx
        pop %r11
        jmp  \name
@@ -184,6 +186,7 @@ xen_pv_trap asm_exc_xen_hypervisor_callback
 SYM_CODE_START(xen_early_idt_handler_array)
        i = 0
        .rept NUM_EXCEPTION_VECTORS
+       UNWIND_HINT_EMPTY
        pop %rcx
        pop %r11
        jmp early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE
@@ -210,11 +213,13 @@ hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
  * rsp->rax            }
  */
 SYM_CODE_START(xen_iret)
+       UNWIND_HINT_EMPTY
        pushq $0
        jmp hypercall_iret
 SYM_CODE_END(xen_iret)
 
 SYM_CODE_START(xen_sysret64)
+       UNWIND_HINT_EMPTY
        /*
         * We're already on the usermode stack at this point, but
         * still with the kernel gs, so we can easily switch back.
@@ -250,7 +255,8 @@ SYM_CODE_END(xen_sysret64)
  */
 
 /* Normal 64-bit system call target */
-SYM_FUNC_START(xen_syscall_target)
+SYM_CODE_START(xen_syscall_target)
+       UNWIND_HINT_EMPTY
        popq %rcx
        popq %r11
 
@@ -263,12 +269,13 @@ SYM_FUNC_START(xen_syscall_target)
        movq $__USER_CS, 1*8(%rsp)
 
        jmp entry_SYSCALL_64_after_hwframe
-SYM_FUNC_END(xen_syscall_target)
+SYM_CODE_END(xen_syscall_target)
 
 #ifdef CONFIG_IA32_EMULATION
 
 /* 32-bit compat syscall target */
-SYM_FUNC_START(xen_syscall32_target)
+SYM_CODE_START(xen_syscall32_target)
+       UNWIND_HINT_EMPTY
        popq %rcx
        popq %r11
 
@@ -281,10 +288,11 @@ SYM_FUNC_START(xen_syscall32_target)
        movq $__USER32_CS, 1*8(%rsp)
 
        jmp entry_SYSCALL_compat_after_hwframe
-SYM_FUNC_END(xen_syscall32_target)
+SYM_CODE_END(xen_syscall32_target)
 
 /* 32-bit compat sysenter target */
-SYM_FUNC_START(xen_sysenter_target)
+SYM_CODE_START(xen_sysenter_target)
+       UNWIND_HINT_EMPTY
        /*
         * NB: Xen is polite and clears TF from EFLAGS for us.  This means
         * that we don't need to guard against single step exceptions here.
@@ -301,17 +309,18 @@ SYM_FUNC_START(xen_sysenter_target)
        movq $__USER32_CS, 1*8(%rsp)
 
        jmp entry_SYSENTER_compat_after_hwframe
-SYM_FUNC_END(xen_sysenter_target)
+SYM_CODE_END(xen_sysenter_target)
 
 #else /* !CONFIG_IA32_EMULATION */
 
-SYM_FUNC_START_ALIAS(xen_syscall32_target)
-SYM_FUNC_START(xen_sysenter_target)
+SYM_CODE_START(xen_syscall32_target)
+SYM_CODE_START(xen_sysenter_target)
+       UNWIND_HINT_EMPTY
        lea 16(%rsp), %rsp      /* strip %rcx, %r11 */
        mov $-ENOSYS, %rax
        pushq $0
        jmp hypercall_iret
-SYM_FUNC_END(xen_sysenter_target)
-SYM_FUNC_END_ALIAS(xen_syscall32_target)
+SYM_CODE_END(xen_sysenter_target)
+SYM_CODE_END(xen_syscall32_target)
 
 #endif /* CONFIG_IA32_EMULATION */