Commit f1a033cc authored by Juergen Gross's avatar Juergen Gross Committed by Peter Zijlstra
Browse files

x86/paravirt: Use common macro for creating simple asm paravirt functions 



There are some paravirt assembler functions which are sharing a common
pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them.

Note that this macro is including explicit alignment of the generated
functions, leading to __raw_callee_save___kvm_vcpu_is_preempted(),
_paravirt_nop() and paravirt_ret0() to be aligned at 4 byte boundaries
now.

The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as
it is included in paravirt_types.h already.

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarSrivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Link: https://lkml.kernel.org/r/20221109134418.6516-1-jgross@suse.com
parent 5736b1b7

arch/x86/include/asm/paravirt.h

+12 −0
Original line number Diff line number Diff line
@@ -731,6 +731,18 @@ static __always_inline unsigned long arch_local_irq_save(void) 
#undef PVOP_VCALL4

#undef PVOP_CALL4



#define DEFINE_PARAVIRT_ASM(func, instr, sec)		\

	asm (".pushsection " #sec ", \"ax\"\n"		\

	     ".global " #func "\n\t"			\

	     ".type " #func ", @function\n\t"		\

	     ASM_FUNC_ALIGN "\n"			\

	     #func ":\n\t"				\

	     ASM_ENDBR					\

	     instr "\n\t"				\

	     ASM_RET					\

	     ".size " #func ", . - " #func "\n\t"	\

	     ".popsection")



extern void default_banner(void);



#else  /* __ASSEMBLY__ */

arch/x86/include/asm/qspinlock_paravirt.h

+20 −27
Original line number Diff line number Diff line
@@ -14,8 +14,6 @@ 


__PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text");

#define __pv_queued_spin_unlock	__pv_queued_spin_unlock

#define PV_UNLOCK		"__raw_callee_save___pv_queued_spin_unlock"

#define PV_UNLOCK_SLOWPATH	"__raw_callee_save___pv_queued_spin_unlock_slowpath"



/*

 * Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock
@@ -37,32 +35,27 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text"); 
 *   rsi = lockval           (second argument)

 *   rdx = internal variable (set to 0)

 */

asm    (".pushsection .spinlock.text, \"ax\";"

	".globl " PV_UNLOCK ";"

	".type " PV_UNLOCK ", @function;"

	ASM_FUNC_ALIGN

	PV_UNLOCK ": "

	ASM_ENDBR

	FRAME_BEGIN

	"push  %rdx;"

	"mov   $0x1,%eax;"

	"xor   %edx,%edx;"

	LOCK_PREFIX "cmpxchg %dl,(%rdi);"

	"cmp   $0x1,%al;"

	"jne   .slowpath;"

	"pop   %rdx;"

#define PV_UNLOCK_ASM							\

	FRAME_BEGIN							\

	"push  %rdx\n\t"						\

	"mov   $0x1,%eax\n\t"						\

	"xor   %edx,%edx\n\t"						\

	LOCK_PREFIX "cmpxchg %dl,(%rdi)\n\t"				\

	"cmp   $0x1,%al\n\t"						\

	"jne   .slowpath\n\t"						\

	"pop   %rdx\n\t"						\

	FRAME_END							\

	ASM_RET								\

	".slowpath:\n\t"						\

	"push   %rsi\n\t"						\

	"movzbl %al,%esi\n\t"						\

	"call __raw_callee_save___pv_queued_spin_unlock_slowpath\n\t"	\

	"pop    %rsi\n\t"						\

	"pop    %rdx\n\t"						\

	FRAME_END

	ASM_RET

	".slowpath: "

	"push   %rsi;"

	"movzbl %al,%esi;"

	"call " PV_UNLOCK_SLOWPATH ";"

	"pop    %rsi;"

	"pop    %rdx;"

	FRAME_END

	ASM_RET

	".size " PV_UNLOCK ", .-" PV_UNLOCK ";"

	".popsection");



DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock,

		    PV_UNLOCK_ASM, .spinlock.text);



#else /* CONFIG_64BIT */

arch/x86/kernel/kvm.c

+6 −13
Original line number Diff line number Diff line
@@ -798,20 +798,13 @@ extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); 
 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and

 * restoring to/from the stack.

 */

asm(

".pushsection .text;"

".global __raw_callee_save___kvm_vcpu_is_preempted;"

".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"

ASM_FUNC_ALIGN

"__raw_callee_save___kvm_vcpu_is_preempted:"

ASM_ENDBR

"movq	__per_cpu_offset(,%rdi,8), %rax;"

"cmpb	$0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"

"setne	%al;"

ASM_RET

".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"

".popsection");

#define PV_VCPU_PREEMPTED_ASM						     \

 "movq   __per_cpu_offset(,%rdi,8), %rax\n\t"				     \

 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \

 "setne  %al\n\t"



DEFINE_PARAVIRT_ASM(__raw_callee_save___kvm_vcpu_is_preempted,

		    PV_VCPU_PREEMPTED_ASM, .text);

#endif



static void __init kvm_guest_init(void)

arch/x86/kernel/paravirt.c

+2 −21
Original line number Diff line number Diff line
@@ -37,29 +37,10 @@ 
 * nop stub, which must not clobber anything *including the stack* to

 * avoid confusing the entry prologues.

 */

extern void _paravirt_nop(void);

asm (".pushsection .entry.text, \"ax\"\n"

     ".global _paravirt_nop\n"

     ASM_FUNC_ALIGN

     "_paravirt_nop:\n\t"

     ASM_ENDBR

     ASM_RET

     ".size _paravirt_nop, . - _paravirt_nop\n\t"

     ".type _paravirt_nop, @function\n\t"

     ".popsection");

DEFINE_PARAVIRT_ASM(_paravirt_nop, "", .entry.text);



/* stub always returning 0. */

asm (".pushsection .entry.text, \"ax\"\n"

     ".global paravirt_ret0\n"

     ASM_FUNC_ALIGN

     "paravirt_ret0:\n\t"

     ASM_ENDBR

     "xor %" _ASM_AX ", %" _ASM_AX ";\n\t"

     ASM_RET

     ".size paravirt_ret0, . - paravirt_ret0\n\t"

     ".type paravirt_ret0, @function\n\t"

     ".popsection");



DEFINE_PARAVIRT_ASM(paravirt_ret0, "xor %eax,%eax", .entry.text);



void __init default_banner(void)

{