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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: Juergen Gross <jgross@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Link: https://lkml.kernel.org/r/20221109134418.6516-1-jgross@suse.com
This commit is contained in:
Juergen Gross 2022-11-09 14:44:18 +01:00 committed by Peter Zijlstra
parent 5736b1b701
commit f1a033cc6b
4 changed files with 40 additions and 61 deletions
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12
arch/x86/include/asm/paravirt.h
View File

@ -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__ */

47
arch/x86/include/asm/qspinlock_paravirt.h
View File

@ -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 */

19
arch/x86/kernel/kvm.c
View File

@ -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)

23
arch/x86/kernel/paravirt.c
View File

@ -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)
{