xref: /linux/arch/x86/include/asm/paravirt_types.h (revision ac633ba77c84fa5be1ec081967be081d6e25577e)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_PARAVIRT_TYPES_H
3 #define _ASM_X86_PARAVIRT_TYPES_H
4 
5 #ifdef CONFIG_PARAVIRT
6 
7 #ifndef __ASSEMBLER__
8 #include <linux/types.h>
9 
10 #include <asm/paravirt-base.h>
11 #include <asm/desc_defs.h>
12 #include <asm/pgtable_types.h>
13 #include <asm/nospec-branch.h>
14 
15 struct thread_struct;
16 struct mm_struct;
17 struct task_struct;
18 struct cpumask;
19 struct flush_tlb_info;
20 struct vm_area_struct;
21 
22 #ifdef CONFIG_PARAVIRT_XXL
23 struct pv_lazy_ops {
24 	/* Set deferred update mode, used for batching operations. */
25 	void (*enter)(void);
26 	void (*leave)(void);
27 	void (*flush)(void);
28 } __no_randomize_layout;
29 #endif
30 
31 struct pv_cpu_ops {
32 	/* hooks for various privileged instructions */
33 #ifdef CONFIG_PARAVIRT_XXL
34 	unsigned long (*get_debugreg)(int regno);
35 	void (*set_debugreg)(int regno, unsigned long value);
36 
37 	unsigned long (*read_cr0)(void);
38 	void (*write_cr0)(unsigned long);
39 
40 	void (*write_cr4)(unsigned long);
41 
42 	/* Segment descriptor handling */
43 	void (*load_tr_desc)(void);
44 	void (*load_gdt)(const struct desc_ptr *);
45 	void (*load_idt)(const struct desc_ptr *);
46 	void (*set_ldt)(const void *desc, unsigned entries);
47 	unsigned long (*store_tr)(void);
48 	void (*load_tls)(struct thread_struct *t, unsigned int cpu);
49 	void (*load_gs_index)(unsigned int idx);
50 	void (*write_ldt_entry)(struct desc_struct *ldt, int entrynum,
51 				const void *desc);
52 	void (*write_gdt_entry)(struct desc_struct *,
53 				int entrynum, const void *desc, int size);
54 	void (*write_idt_entry)(gate_desc *,
55 				int entrynum, const gate_desc *gate);
56 	void (*alloc_ldt)(struct desc_struct *ldt, unsigned entries);
57 	void (*free_ldt)(struct desc_struct *ldt, unsigned entries);
58 
59 	void (*load_sp0)(unsigned long sp0);
60 
61 #ifdef CONFIG_X86_IOPL_IOPERM
62 	void (*invalidate_io_bitmap)(void);
63 	void (*update_io_bitmap)(void);
64 #endif
65 
66 	/* cpuid emulation, mostly so that caps bits can be disabled */
67 	void (*cpuid)(unsigned int *eax, unsigned int *ebx,
68 		      unsigned int *ecx, unsigned int *edx);
69 
70 	/* Unsafe MSR operations.  These will warn or panic on failure. */
71 	u64 (*read_msr)(u32 msr);
72 	void (*write_msr)(u32 msr, u64 val);
73 
74 	/*
75 	 * Safe MSR operations.
76 	 * Returns 0 or -EIO.
77 	 */
78 	int (*read_msr_safe)(u32 msr, u64 *val);
79 	int (*write_msr_safe)(u32 msr, u64 val);
80 
81 	u64 (*read_pmc)(int counter);
82 
83 	void (*start_context_switch)(struct task_struct *prev);
84 	void (*end_context_switch)(struct task_struct *next);
85 #endif
86 } __no_randomize_layout;
87 
88 struct pv_irq_ops {
89 #ifdef CONFIG_PARAVIRT_XXL
90 	/*
91 	 * Get/set interrupt state.  save_fl is expected to use X86_EFLAGS_IF;
92 	 * all other bits returned from save_fl are undefined.
93 	 *
94 	 * NOTE: These functions callers expect the callee to preserve
95 	 * more registers than the standard C calling convention.
96 	 */
97 	struct paravirt_callee_save save_fl;
98 	struct paravirt_callee_save irq_disable;
99 	struct paravirt_callee_save irq_enable;
100 #endif
101 	void (*safe_halt)(void);
102 	void (*halt)(void);
103 } __no_randomize_layout;
104 
105 struct pv_mmu_ops {
106 	/* TLB operations */
107 	void (*flush_tlb_user)(void);
108 	void (*flush_tlb_kernel)(void);
109 	void (*flush_tlb_one_user)(unsigned long addr);
110 	void (*flush_tlb_multi)(const struct cpumask *cpus,
111 				const struct flush_tlb_info *info);
112 
113 	/* Hook for intercepting the destruction of an mm_struct. */
114 	void (*exit_mmap)(struct mm_struct *mm);
115 	void (*notify_page_enc_status_changed)(unsigned long pfn, int npages, bool enc);
116 
117 #ifdef CONFIG_PARAVIRT_XXL
118 	struct paravirt_callee_save read_cr2;
119 	void (*write_cr2)(unsigned long);
120 
121 	unsigned long (*read_cr3)(void);
122 	void (*write_cr3)(unsigned long);
123 
124 	/* Hook for intercepting the creation/use of an mm_struct. */
125 	void (*enter_mmap)(struct mm_struct *mm);
126 
127 	/* Hooks for allocating and freeing a pagetable top-level */
128 	int  (*pgd_alloc)(struct mm_struct *mm);
129 	void (*pgd_free)(struct mm_struct *mm, pgd_t *pgd);
130 
131 	/*
132 	 * Hooks for allocating/releasing pagetable pages when they're
133 	 * attached to a pagetable
134 	 */
135 	void (*alloc_pte)(struct mm_struct *mm, unsigned long pfn);
136 	void (*alloc_pmd)(struct mm_struct *mm, unsigned long pfn);
137 	void (*alloc_pud)(struct mm_struct *mm, unsigned long pfn);
138 	void (*alloc_p4d)(struct mm_struct *mm, unsigned long pfn);
139 	void (*release_pte)(unsigned long pfn);
140 	void (*release_pmd)(unsigned long pfn);
141 	void (*release_pud)(unsigned long pfn);
142 	void (*release_p4d)(unsigned long pfn);
143 
144 	/* Pagetable manipulation functions */
145 	void (*set_pte)(pte_t *ptep, pte_t pteval);
146 	void (*set_pmd)(pmd_t *pmdp, pmd_t pmdval);
147 
148 	pte_t (*ptep_modify_prot_start)(struct vm_area_struct *vma, unsigned long addr,
149 					pte_t *ptep);
150 	void (*ptep_modify_prot_commit)(struct vm_area_struct *vma, unsigned long addr,
151 					pte_t *ptep, pte_t pte);
152 
153 	struct paravirt_callee_save pte_val;
154 	struct paravirt_callee_save make_pte;
155 
156 	struct paravirt_callee_save pgd_val;
157 	struct paravirt_callee_save make_pgd;
158 
159 	void (*set_pud)(pud_t *pudp, pud_t pudval);
160 
161 	struct paravirt_callee_save pmd_val;
162 	struct paravirt_callee_save make_pmd;
163 
164 	struct paravirt_callee_save pud_val;
165 	struct paravirt_callee_save make_pud;
166 
167 	void (*set_p4d)(p4d_t *p4dp, p4d_t p4dval);
168 
169 	struct paravirt_callee_save p4d_val;
170 	struct paravirt_callee_save make_p4d;
171 
172 	void (*set_pgd)(pgd_t *pgdp, pgd_t pgdval);
173 
174 	struct pv_lazy_ops lazy_mode;
175 
176 	/* dom0 ops */
177 
178 	/* Sometimes the physical address is a pfn, and sometimes its
179 	   an mfn.  We can tell which is which from the index. */
180 	void (*set_fixmap)(unsigned /* enum fixed_addresses */ idx,
181 			   phys_addr_t phys, pgprot_t flags);
182 #endif
183 } __no_randomize_layout;
184 
185 /* This contains all the paravirt structures: we get a convenient
186  * number for each function using the offset which we use to indicate
187  * what to patch. */
188 struct paravirt_patch_template {
189 	struct pv_cpu_ops	cpu;
190 	struct pv_irq_ops	irq;
191 	struct pv_mmu_ops	mmu;
192 } __no_randomize_layout;
193 
194 extern struct paravirt_patch_template pv_ops;
195 
196 #define paravirt_ptr(array, op)	[paravirt_opptr] "m" (array.op)
197 
198 /*
199  * This generates an indirect call based on the operation type number.
200  *
201  * Since alternatives run after enabling CET/IBT -- the latter setting/clearing
202  * capabilities and the former requiring all capabilities being finalized --
203  * these indirect calls are subject to IBT and the paravirt stubs should have
204  * ENDBR on.
205  *
206  * OTOH since this is effectively a __nocfi indirect call, the paravirt stubs
207  * don't need to bother with CFI prefixes.
208  */
209 #define PARAVIRT_CALL					\
210 	ANNOTATE_RETPOLINE_SAFE "\n\t"			\
211 	"call *%[paravirt_opptr]"
212 
213 /*
214  * These macros are intended to wrap calls through one of the paravirt
215  * ops structs, so that they can be later identified and patched at
216  * runtime.
217  *
218  * Normally, a call to a pv_op function is a simple indirect call:
219  * (pv_op_struct.operations)(args...).
220  *
221  * Unfortunately, this is a relatively slow operation for modern CPUs,
222  * because it cannot necessarily determine what the destination
223  * address is.  In this case, the address is a runtime constant, so at
224  * the very least we can patch the call to a simple direct call, or,
225  * ideally, patch an inline implementation into the callsite.  (Direct
226  * calls are essentially free, because the call and return addresses
227  * are completely predictable.)
228  *
229  * For i386, these macros rely on the standard gcc "regparm(3)" calling
230  * convention, in which the first three arguments are placed in %eax,
231  * %edx, %ecx (in that order), and the remaining arguments are placed
232  * on the stack.  All caller-save registers (eax,edx,ecx) are expected
233  * to be modified (either clobbered or used for return values).
234  * X86_64, on the other hand, already specifies a register-based calling
235  * conventions, returning at %rax, with parameters going in %rdi, %rsi,
236  * %rdx, and %rcx. Note that for this reason, x86_64 does not need any
237  * special handling for dealing with 4 arguments, unlike i386.
238  * However, x86_64 also has to clobber all caller saved registers, which
239  * unfortunately, are quite a bit (r8 - r11)
240  *
241  * Unfortunately there's no way to get gcc to generate the args setup
242  * for the call, and then allow the call itself to be generated by an
243  * inline asm.  Because of this, we must do the complete arg setup and
244  * return value handling from within these macros.  This is fairly
245  * cumbersome.
246  *
247  * There are 5 sets of PVOP_* macros for dealing with 0-4 arguments.
248  * It could be extended to more arguments, but there would be little
249  * to be gained from that.  For each number of arguments, there are
250  * two VCALL and CALL variants for void and non-void functions.
251  *
252  * When there is a return value, the invoker of the macro must specify
253  * the return type.  The macro then uses sizeof() on that type to
254  * determine whether it's a 32 or 64 bit value and places the return
255  * in the right register(s) (just %eax for 32-bit, and %edx:%eax for
256  * 64-bit). For x86_64 machines, it just returns in %rax regardless of
257  * the return value size.
258  *
259  * 64-bit arguments are passed as a pair of adjacent 32-bit arguments;
260  * i386 also passes 64-bit arguments as a pair of adjacent 32-bit arguments
261  * in low,high order
262  *
263  * Small structures are passed and returned in registers.  The macro
264  * calling convention can't directly deal with this, so the wrapper
265  * functions must do it.
266  *
267  * These PVOP_* macros are only defined within this header.  This
268  * means that all uses must be wrapped in inline functions.  This also
269  * makes sure the incoming and outgoing types are always correct.
270  */
271 #ifdef CONFIG_X86_32
272 #define PVOP_CALL_ARGS							\
273 	unsigned long __eax = __eax, __edx = __edx, __ecx = __ecx;
274 
275 #define PVOP_CALL_ARG1(x)		"a" ((unsigned long)(x))
276 #define PVOP_CALL_ARG2(x)		"d" ((unsigned long)(x))
277 #define PVOP_CALL_ARG3(x)		"c" ((unsigned long)(x))
278 
279 #define PVOP_VCALL_CLOBBERS		"=a" (__eax), "=d" (__edx),	\
280 					"=c" (__ecx)
281 #define PVOP_CALL_CLOBBERS		PVOP_VCALL_CLOBBERS
282 
283 #define PVOP_VCALLEE_CLOBBERS		"=a" (__eax), "=d" (__edx)
284 #define PVOP_CALLEE_CLOBBERS		PVOP_VCALLEE_CLOBBERS
285 
286 #define EXTRA_CLOBBERS
287 #define VEXTRA_CLOBBERS
288 #else  /* CONFIG_X86_64 */
289 /* [re]ax isn't an arg, but the return val */
290 #define PVOP_CALL_ARGS						\
291 	unsigned long __edi = __edi, __esi = __esi,		\
292 		__edx = __edx, __ecx = __ecx, __eax = __eax;
293 
294 #define PVOP_CALL_ARG1(x)		"D" ((unsigned long)(x))
295 #define PVOP_CALL_ARG2(x)		"S" ((unsigned long)(x))
296 #define PVOP_CALL_ARG3(x)		"d" ((unsigned long)(x))
297 #define PVOP_CALL_ARG4(x)		"c" ((unsigned long)(x))
298 
299 #define PVOP_VCALL_CLOBBERS	"=D" (__edi),				\
300 				"=S" (__esi), "=d" (__edx),		\
301 				"=c" (__ecx)
302 #define PVOP_CALL_CLOBBERS	PVOP_VCALL_CLOBBERS, "=a" (__eax)
303 
304 /*
305  * void functions are still allowed [re]ax for scratch.
306  *
307  * The ZERO_CALL_USED REGS feature may end up zeroing out callee-saved
308  * registers. Make sure we model this with the appropriate clobbers.
309  */
310 #ifdef CONFIG_ZERO_CALL_USED_REGS
311 #define PVOP_VCALLEE_CLOBBERS	"=a" (__eax), PVOP_VCALL_CLOBBERS
312 #else
313 #define PVOP_VCALLEE_CLOBBERS	"=a" (__eax)
314 #endif
315 #define PVOP_CALLEE_CLOBBERS	PVOP_VCALLEE_CLOBBERS
316 
317 #define EXTRA_CLOBBERS	 , "r8", "r9", "r10", "r11"
318 #define VEXTRA_CLOBBERS	 , "rax", "r8", "r9", "r10", "r11"
319 #endif	/* CONFIG_X86_32 */
320 
321 #define PVOP_RETVAL(rettype)						\
322 	({	unsigned long __mask = ~0UL;				\
323 		BUILD_BUG_ON(sizeof(rettype) > sizeof(unsigned long));	\
324 		switch (sizeof(rettype)) {				\
325 		case 1: __mask =       0xffUL; break;			\
326 		case 2: __mask =     0xffffUL; break;			\
327 		case 4: __mask = 0xffffffffUL; break;			\
328 		default: break;						\
329 		}							\
330 		__mask & __eax;						\
331 	})
332 
333 /*
334  * Use alternative patching for paravirt calls:
335  * - For replacing an indirect call with a direct one, use the "normal"
336  *   ALTERNATIVE() macro with the indirect call as the initial code sequence,
337  *   which will be replaced with the related direct call by using the
338  *   ALT_FLAG_DIRECT_CALL special case and the "always on" feature.
339  * - In case the replacement is either a direct call or a short code sequence
340  *   depending on a feature bit, the ALTERNATIVE_2() macro is being used.
341  *   The indirect call is the initial code sequence again, while the special
342  *   code sequence is selected with the specified feature bit. In case the
343  *   feature is not active, the direct call is used as above via the
344  *   ALT_FLAG_DIRECT_CALL special case and the "always on" feature.
345  */
346 #define ____PVOP_CALL(ret, array, op, call_clbr, extra_clbr, ...)	\
347 	({								\
348 		PVOP_CALL_ARGS;						\
349 		asm volatile(ALTERNATIVE(PARAVIRT_CALL, ALT_CALL_INSTR,	\
350 				ALT_CALL_ALWAYS)			\
351 			     : call_clbr, ASM_CALL_CONSTRAINT		\
352 			     : paravirt_ptr(array, op),			\
353 			       ##__VA_ARGS__				\
354 			     : "memory", "cc" extra_clbr);		\
355 		ret;							\
356 	})
357 
358 #define ____PVOP_ALT_CALL(ret, array, op, alt, cond, call_clbr,		\
359 			  extra_clbr, ...)				\
360 	({								\
361 		PVOP_CALL_ARGS;						\
362 		asm volatile(ALTERNATIVE_2(PARAVIRT_CALL,		\
363 				 ALT_CALL_INSTR, ALT_CALL_ALWAYS,	\
364 				 alt, cond)				\
365 			     : call_clbr, ASM_CALL_CONSTRAINT		\
366 			     : paravirt_ptr(array, op),			\
367 			       ##__VA_ARGS__				\
368 			     : "memory", "cc" extra_clbr);		\
369 		ret;							\
370 	})
371 
372 #define __PVOP_CALL(rettype, array, op, ...)				\
373 	____PVOP_CALL(PVOP_RETVAL(rettype), array, op,			\
374 		      PVOP_CALL_CLOBBERS, EXTRA_CLOBBERS, ##__VA_ARGS__)
375 
376 #define __PVOP_ALT_CALL(rettype, array, op, alt, cond, ...)		\
377 	____PVOP_ALT_CALL(PVOP_RETVAL(rettype), array, op, alt, cond,	\
378 			  PVOP_CALL_CLOBBERS, EXTRA_CLOBBERS,		\
379 			  ##__VA_ARGS__)
380 
381 #define __PVOP_CALLEESAVE(rettype, array, op, ...)			\
382 	____PVOP_CALL(PVOP_RETVAL(rettype), array, op.func,		\
383 		      PVOP_CALLEE_CLOBBERS, , ##__VA_ARGS__)
384 
385 #define __PVOP_ALT_CALLEESAVE(rettype, array, op, alt, cond, ...)	\
386 	____PVOP_ALT_CALL(PVOP_RETVAL(rettype), array, op.func, alt, cond, \
387 			  PVOP_CALLEE_CLOBBERS, , ##__VA_ARGS__)
388 
389 
390 #define __PVOP_VCALL(array, op, ...)					\
391 	(void)____PVOP_CALL(, array, op, PVOP_VCALL_CLOBBERS,		\
392 		       VEXTRA_CLOBBERS, ##__VA_ARGS__)
393 
394 #define __PVOP_ALT_VCALL(array, op, alt, cond, ...)			\
395 	(void)____PVOP_ALT_CALL(, array, op, alt, cond,			\
396 				PVOP_VCALL_CLOBBERS, VEXTRA_CLOBBERS,	\
397 				##__VA_ARGS__)
398 
399 #define __PVOP_VCALLEESAVE(array, op, ...)				\
400 	(void)____PVOP_CALL(, array, op.func,				\
401 			    PVOP_VCALLEE_CLOBBERS, , ##__VA_ARGS__)
402 
403 #define __PVOP_ALT_VCALLEESAVE(array, op, alt, cond, ...)		\
404 	(void)____PVOP_ALT_CALL(, array, op.func, alt, cond,		\
405 				PVOP_VCALLEE_CLOBBERS, , ##__VA_ARGS__)
406 
407 
408 #define PVOP_CALL0(rettype, array, op)					\
409 	__PVOP_CALL(rettype, array, op)
410 #define PVOP_VCALL0(array, op)						\
411 	__PVOP_VCALL(array, op)
412 #define PVOP_ALT_CALL0(rettype, array, op, alt, cond)			\
413 	__PVOP_ALT_CALL(rettype, array, op, alt, cond)
414 #define PVOP_ALT_VCALL0(array, op, alt, cond)				\
415 	__PVOP_ALT_VCALL(array, op, alt, cond)
416 
417 #define PVOP_CALLEE0(rettype, array, op)				\
418 	__PVOP_CALLEESAVE(rettype, array, op)
419 #define PVOP_VCALLEE0(array, op)					\
420 	__PVOP_VCALLEESAVE(array, op)
421 #define PVOP_ALT_CALLEE0(rettype, array, op, alt, cond)			\
422 	__PVOP_ALT_CALLEESAVE(rettype, array, op, alt, cond)
423 #define PVOP_ALT_VCALLEE0(array, op, alt, cond)				\
424 	__PVOP_ALT_VCALLEESAVE(array, op, alt, cond)
425 
426 
427 #define PVOP_CALL1(rettype, array, op, arg1)				\
428 	__PVOP_CALL(rettype, array, op, PVOP_CALL_ARG1(arg1))
429 #define PVOP_VCALL1(array, op, arg1)					\
430 	__PVOP_VCALL(array, op, PVOP_CALL_ARG1(arg1))
431 #define PVOP_ALT_VCALL1(array, op, arg1, alt, cond)			\
432 	__PVOP_ALT_VCALL(array, op, alt, cond, PVOP_CALL_ARG1(arg1))
433 
434 #define PVOP_CALLEE1(rettype, array, op, arg1)				\
435 	__PVOP_CALLEESAVE(rettype, array, op, PVOP_CALL_ARG1(arg1))
436 #define PVOP_VCALLEE1(array, op, arg1)					\
437 	__PVOP_VCALLEESAVE(array, op, PVOP_CALL_ARG1(arg1))
438 #define PVOP_ALT_CALLEE1(rettype, array, op, arg1, alt, cond)		\
439 	__PVOP_ALT_CALLEESAVE(rettype, array, op, alt, cond, PVOP_CALL_ARG1(arg1))
440 #define PVOP_ALT_VCALLEE1(array, op, arg1, alt, cond)			\
441 	__PVOP_ALT_VCALLEESAVE(array, op, alt, cond, PVOP_CALL_ARG1(arg1))
442 
443 
444 #define PVOP_CALL2(rettype, array, op, arg1, arg2)			\
445 	__PVOP_CALL(rettype, array, op, PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2))
446 #define PVOP_VCALL2(array, op, arg1, arg2)				\
447 	__PVOP_VCALL(array, op, PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2))
448 
449 #define PVOP_CALL3(rettype, array, op, arg1, arg2, arg3)		\
450 	__PVOP_CALL(rettype, array, op, PVOP_CALL_ARG1(arg1),		\
451 		    PVOP_CALL_ARG2(arg2), PVOP_CALL_ARG3(arg3))
452 #define PVOP_VCALL3(array, op, arg1, arg2, arg3)			\
453 	__PVOP_VCALL(array, op, PVOP_CALL_ARG1(arg1),			\
454 		     PVOP_CALL_ARG2(arg2), PVOP_CALL_ARG3(arg3))
455 
456 #define PVOP_CALL4(rettype, array, op, arg1, arg2, arg3, arg4)		\
457 	__PVOP_CALL(rettype, array, op,					\
458 		    PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2),		\
459 		    PVOP_CALL_ARG3(arg3), PVOP_CALL_ARG4(arg4))
460 #define PVOP_VCALL4(array, op, arg1, arg2, arg3, arg4)			\
461 	__PVOP_VCALL(array, op, PVOP_CALL_ARG1(arg1), PVOP_CALL_ARG2(arg2), \
462 		     PVOP_CALL_ARG3(arg3), PVOP_CALL_ARG4(arg4))
463 
464 #endif	/* __ASSEMBLER__ */
465 
466 #define ALT_NOT_XEN	ALT_NOT(X86_FEATURE_XENPV)
467 
468 #ifdef CONFIG_X86_32
469 /* save and restore all caller-save registers, except return value */
470 #define PV_SAVE_ALL_CALLER_REGS		"pushl %ecx;"
471 #define PV_RESTORE_ALL_CALLER_REGS	"popl  %ecx;"
472 #else
473 /* save and restore all caller-save registers, except return value */
474 #define PV_SAVE_ALL_CALLER_REGS						\
475 	"push %rcx;"							\
476 	"push %rdx;"							\
477 	"push %rsi;"							\
478 	"push %rdi;"							\
479 	"push %r8;"							\
480 	"push %r9;"							\
481 	"push %r10;"							\
482 	"push %r11;"
483 #define PV_RESTORE_ALL_CALLER_REGS					\
484 	"pop %r11;"							\
485 	"pop %r10;"							\
486 	"pop %r9;"							\
487 	"pop %r8;"							\
488 	"pop %rdi;"							\
489 	"pop %rsi;"							\
490 	"pop %rdx;"							\
491 	"pop %rcx;"
492 #endif
493 
494 /*
495  * Generate a thunk around a function which saves all caller-save
496  * registers except for the return value.  This allows C functions to
497  * be called from assembler code where fewer than normal registers are
498  * available.  It may also help code generation around calls from C
499  * code if the common case doesn't use many registers.
500  *
501  * When a callee is wrapped in a thunk, the caller can assume that all
502  * arg regs and all scratch registers are preserved across the
503  * call. The return value in rax/eax will not be saved, even for void
504  * functions.
505  */
506 #define PV_THUNK_NAME(func) "__raw_callee_save_" #func
507 #define __PV_CALLEE_SAVE_REGS_THUNK(func, section)			\
508 	extern typeof(func) __raw_callee_save_##func;			\
509 									\
510 	asm(".pushsection " section ", \"ax\";"				\
511 	    ".globl " PV_THUNK_NAME(func) ";"				\
512 	    ".type " PV_THUNK_NAME(func) ", @function;"			\
513 	    ASM_FUNC_ALIGN						\
514 	    PV_THUNK_NAME(func) ":"					\
515 	    ASM_ENDBR							\
516 	    FRAME_BEGIN							\
517 	    PV_SAVE_ALL_CALLER_REGS					\
518 	    "call " #func ";"						\
519 	    PV_RESTORE_ALL_CALLER_REGS					\
520 	    FRAME_END							\
521 	    ASM_RET							\
522 	    ".size " PV_THUNK_NAME(func) ", .-" PV_THUNK_NAME(func) ";"	\
523 	    ".popsection")
524 
525 #define PV_CALLEE_SAVE_REGS_THUNK(func)			\
526 	__PV_CALLEE_SAVE_REGS_THUNK(func, ".text")
527 
528 /* Get a reference to a callee-save function */
529 #define PV_CALLEE_SAVE(func)						\
530 	((struct paravirt_callee_save) { __raw_callee_save_##func })
531 
532 /* Promise that "func" already uses the right calling convention */
533 #define __PV_IS_CALLEE_SAVE(func)			\
534 	((struct paravirt_callee_save) { func })
535 
536 #endif  /* CONFIG_PARAVIRT */
537 #endif	/* _ASM_X86_PARAVIRT_TYPES_H */
538