Commit cde07a4e authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

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: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8b042a09c69e8645f3b133ef6653ba28f896807d.1611263462.git.jpoimboe@redhat.com
parent c26acfbb

arch/x86/xen/Makefile

+0 −1
Original line number Diff line number Diff line 
# 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

arch/x86/xen/xen-asm.S

+19 −10
Original line number Diff line number Diff line
@@ -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 */