Commit 20125c87 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/xen: Make save_fl() noinstr 



vmlinux.o: warning: objtool: pv_ops[30]: native_save_fl
vmlinux.o: warning: objtool: pv_ops[30]: __raw_callee_save_xen_save_fl
vmlinux.o: warning: objtool: pv_ops[30]: xen_save_fl_direct
vmlinux.o: warning: objtool: lockdep_hardirqs_off()+0x73: call to pv_ops[30]() leaves .noinstr.text section

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20210624095148.749712274@infradead.org
parent 7361fac0

arch/x86/include/asm/paravirt.h

+5 −2
Original line number Diff line number Diff line
@@ -653,10 +653,10 @@ bool __raw_callee_save___native_vcpu_is_preempted(long cpu); 
 * functions.

 */

#define PV_THUNK_NAME(func) "__raw_callee_save_" #func

#define PV_CALLEE_SAVE_REGS_THUNK(func)					\

#define __PV_CALLEE_SAVE_REGS_THUNK(func, section)			\

	extern typeof(func) __raw_callee_save_##func;			\

									\

	asm(".pushsection .text;"					\

	asm(".pushsection " section ", \"ax\";"				\

	    ".globl " PV_THUNK_NAME(func) ";"				\

	    ".type " PV_THUNK_NAME(func) ", @function;"			\

	    PV_THUNK_NAME(func) ":"					\
@@ -669,6 +669,9 @@ bool __raw_callee_save___native_vcpu_is_preempted(long cpu); 
	    ".size " PV_THUNK_NAME(func) ", .-" PV_THUNK_NAME(func) ";"	\

	    ".popsection")



#define PV_CALLEE_SAVE_REGS_THUNK(func)			\

	__PV_CALLEE_SAVE_REGS_THUNK(func, ".text")



/* Get a reference to a callee-save function */

#define PV_CALLEE_SAVE(func)						\

	((struct paravirt_callee_save) { __raw_callee_save_##func })

arch/x86/kernel/irqflags.S

+2 −0
Original line number Diff line number Diff line
@@ -7,9 +7,11 @@ 
/*

 * unsigned long native_save_fl(void)

 */

.pushsection .noinstr.text, "ax"

SYM_FUNC_START(native_save_fl)

	pushf

	pop %_ASM_AX

	ret

SYM_FUNC_END(native_save_fl)

.popsection

EXPORT_SYMBOL(native_save_fl)

arch/x86/xen/irq.c

+2 −2
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ void xen_force_evtchn_callback(void) 
	(void)HYPERVISOR_xen_version(0, NULL);

}



asmlinkage __visible unsigned long xen_save_fl(void)

asmlinkage __visible noinstr unsigned long xen_save_fl(void)

{

	struct vcpu_info *vcpu;

	unsigned long flags;
@@ -40,7 +40,7 @@ asmlinkage __visible unsigned long xen_save_fl(void) 
	*/

	return (-flags) & X86_EFLAGS_IF;

}

PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);

__PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl, ".noinstr.text");



asmlinkage __visible void xen_irq_disable(void)

{

arch/x86/xen/xen-asm.S

+16 −16
Original line number Diff line number Diff line
@@ -57,22 +57,6 @@ SYM_FUNC_START(xen_irq_disable_direct) 
	ret

SYM_FUNC_END(xen_irq_disable_direct)



/*

 * (xen_)save_fl is used to get the current interrupt enable status.

 * Callers expect the status to be in X86_EFLAGS_IF, and other bits

 * may be set in the return value.  We take advantage of this by

 * making sure that X86_EFLAGS_IF has the right value (and other bits

 * in that byte are 0), but other bits in the return value are

 * undefined.  We need to toggle the state of the bit, because Xen and

 * x86 use opposite senses (mask vs enable).

 */

SYM_FUNC_START(xen_save_fl_direct)

	testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask

	setz %ah

	addb %ah, %ah

	ret

SYM_FUNC_END(xen_save_fl_direct)



/*

 * Force an event check by making a hypercall, but preserve regs

 * before making the call.
@@ -103,6 +87,22 @@ SYM_FUNC_START(check_events) 
SYM_FUNC_END(check_events)



.pushsection .noinstr.text, "ax"

/*

 * (xen_)save_fl is used to get the current interrupt enable status.

 * Callers expect the status to be in X86_EFLAGS_IF, and other bits

 * may be set in the return value.  We take advantage of this by

 * making sure that X86_EFLAGS_IF has the right value (and other bits

 * in that byte are 0), but other bits in the return value are

 * undefined.  We need to toggle the state of the bit, because Xen and

 * x86 use opposite senses (mask vs enable).

 */

SYM_FUNC_START(xen_save_fl_direct)

	testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask

	setz %ah

	addb %ah, %ah

	ret

SYM_FUNC_END(xen_save_fl_direct)



SYM_FUNC_START(xen_read_cr2)

	FRAME_BEGIN

	_ASM_MOV PER_CPU_VAR(xen_vcpu), %_ASM_AX