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x86/xen: Make save_fl() noinstr

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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: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20210624095148.749712274@infradead.org
This commit is contained in:
Peter Zijlstra 2021-06-24 11:41:17 +02:00
parent 7361fac046
commit 20125c872a
4 changed files with 25 additions and 20 deletions
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7
arch/x86/include/asm/paravirt.h
View File

@ -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 })

2
arch/x86/kernel/irqflags.S
View File

@ -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)

4
arch/x86/xen/irq.c
View File

@ -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)
{

32
arch/x86/xen/xen-asm.S
View File

@ -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