[linux-block.git] / include / linux / objtool.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H

#ifndef __ASSEMBLY__

#include <linux/types.h>

/*
 * This struct is used by asm and inline asm code to manually annotate the
 * location of registers on the stack.
 */
struct unwind_hint {
	u32		ip;
	s16		sp_offset;
	u8		sp_reg;
	u8		type;
	u8		end;
};
#endif

/*
 * UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
 * (the caller's SP right before it made the call).  Used for all callable
 * functions, i.e. all C code and all callable asm functions.
 *
 * UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset
 * points to a fully populated pt_regs from a syscall, interrupt, or exception.
 *
 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
 * sp_reg+sp_offset points to the iret return frame.
 *
 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
 * Useful for code which doesn't have an ELF function annotation.
 */
#define UNWIND_HINT_TYPE_CALL		0
#define UNWIND_HINT_TYPE_REGS		1
#define UNWIND_HINT_TYPE_REGS_PARTIAL	2
#define UNWIND_HINT_TYPE_FUNC		3

#ifdef CONFIG_STACK_VALIDATION

#ifndef __ASSEMBLY__

#define UNWIND_HINT(sp_reg, sp_offset, type, end)		\
	"987: \n\t"						\
	".pushsection .discard.unwind_hints\n\t"		\
	/* struct unwind_hint */				\
	".long 987b - .\n\t"					\
	".short " __stringify(sp_offset) "\n\t"			\
	".byte " __stringify(sp_reg) "\n\t"			\
	".byte " __stringify(type) "\n\t"			\
	".byte " __stringify(end) "\n\t"			\
	".balign 4 \n\t"					\
	".popsection\n\t"

/*
 * This macro marks the given function's stack frame as "non-standard", which
 * tells objtool to ignore the function when doing stack metadata validation.
 * It should only be used in special cases where you're 100% sure it won't
 * affect the reliability of frame pointers and kernel stack traces.
 *
 * For more information, see tools/objtool/Documentation/stack-validation.txt.
 */
#define STACK_FRAME_NON_STANDARD(func) \
	static void __used __section(".discard.func_stack_frame_non_standard") \
		*__func_stack_frame_non_standard_##func = func

/*
 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
 * for the case where a function is intentionally missing frame pointer setup,
 * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
 */
#ifdef CONFIG_FRAME_POINTER
#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
#else
#define STACK_FRAME_NON_STANDARD_FP(func)
#endif

#else /* __ASSEMBLY__ */

/*
 * This macro indicates that the following intra-function call is valid.
 * Any non-annotated intra-function call will cause objtool to issue a warning.
 */
#define ANNOTATE_INTRA_FUNCTION_CALL				\
	999:							\
	.pushsection .discard.intra_function_calls;		\
	.long 999b;						\
	.popsection;

/*
 * In asm, there are two kinds of code: normal C-type callable functions and
 * the rest.  The normal callable functions can be called by other code, and
 * don't do anything unusual with the stack.  Such normal callable functions
 * are annotated with the ENTRY/ENDPROC macros.  Most asm code falls in this
 * category.  In this case, no special debugging annotations are needed because
 * objtool can automatically generate the ORC data for the ORC unwinder to read
 * at runtime.
 *
 * Anything which doesn't fall into the above category, such as syscall and
 * interrupt handlers, tends to not be called directly by other functions, and
 * often does unusual non-C-function-type things with the stack pointer.  Such
 * code needs to be annotated such that objtool can understand it.  The
 * following CFI hint macros are for this type of code.
 *
 * These macros provide hints to objtool about the state of the stack at each
 * instruction.  Objtool starts from the hints and follows the code flow,
 * making automatic CFI adjustments when it sees pushes and pops, filling out
 * the debuginfo as necessary.  It will also warn if it sees any
 * inconsistencies.
 */
.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
.Lunwind_hint_ip_\@:
	.pushsection .discard.unwind_hints
		/* struct unwind_hint */
		.long .Lunwind_hint_ip_\@ - .
		.short \sp_offset
		.byte \sp_reg
		.byte \type
		.byte \end
		.balign 4
	.popsection
.endm

.macro STACK_FRAME_NON_STANDARD func:req
	.pushsection .discard.func_stack_frame_non_standard, "aw"
		.long \func - .
	.popsection
.endm

#endif /* __ASSEMBLY__ */

#else /* !CONFIG_STACK_VALIDATION */

#ifndef __ASSEMBLY__

#define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
	"\n\t"
#define STACK_FRAME_NON_STANDARD(func)
#define STACK_FRAME_NON_STANDARD_FP(func)
#else
#define ANNOTATE_INTRA_FUNCTION_CALL
.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
.endm
.macro STACK_FRAME_NON_STANDARD func:req
.endm
#endif

#endif /* CONFIG_STACK_VALIDATION */

#endif /* _LINUX_OBJTOOL_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
00089c04 JT	2	#ifndef _LINUX_OBJTOOL_H
00089c04 JT	3	#define _LINUX_OBJTOOL_H
9a99417a	4
ee819aed JT	5	#ifndef __ASSEMBLY__
	6
	7	#include <linux/types.h>
	8
	9	/*
	10	* This struct is used by asm and inline asm code to manually annotate the
	11	* location of registers on the stack.
	12	*/
	13	struct unwind_hint {
	14	u32 ip;
	15	s16 sp_offset;
	16	u8 sp_reg;
	17	u8 type;
	18	u8 end;
	19	};
	20	#endif
	21
	22	/*
	23	* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
	24	* (the caller's SP right before it made the call). Used for all callable
	25	* functions, i.e. all C code and all callable asm functions.
	26	*
	27	* UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset
	28	* points to a fully populated pt_regs from a syscall, interrupt, or exception.
	29	*
	30	* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
	31	* sp_reg+sp_offset points to the iret return frame.
b735bd3e JP	32	*
	33	* UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
	34	* Useful for code which doesn't have an ELF function annotation.
ee819aed JT	35	*/
	36	#define UNWIND_HINT_TYPE_CALL 0
	37	#define UNWIND_HINT_TYPE_REGS 1
	38	#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
b735bd3e	39	#define UNWIND_HINT_TYPE_FUNC 3
ee819aed	40
9a99417a	41	#ifdef CONFIG_STACK_VALIDATION
5567c6c3 JT	42
5567c6c3 JT	43	#ifndef __ASSEMBLY__
ee819aed JT	44
	45	#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
	46	"987: \n\t" \
	47	".pushsection .discard.unwind_hints\n\t" \
	48	/* struct unwind_hint */ \
	49	".long 987b - .\n\t" \
	50	".short " __stringify(sp_offset) "\n\t" \
	51	".byte " __stringify(sp_reg) "\n\t" \
	52	".byte " __stringify(type) "\n\t" \
	53	".byte " __stringify(end) "\n\t" \
	54	".balign 4 \n\t" \
	55	".popsection\n\t"
	56
9a99417a JP	57	/*
	58	* This macro marks the given function's stack frame as "non-standard", which
	59	* tells objtool to ignore the function when doing stack metadata validation.
	60	* It should only be used in special cases where you're 100% sure it won't
	61	* affect the reliability of frame pointers and kernel stack traces.
	62	*
	63	* For more information, see tools/objtool/Documentation/stack-validation.txt.
	64	*/
	65	#define STACK_FRAME_NON_STANDARD(func) \
33def849	66	static void __used __section(".discard.func_stack_frame_non_standard") \
9a99417a JP	67	*__func_stack_frame_non_standard_##func = func
9a99417a JP	68
e028c4f7 JP	69	/*
	70	* STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
	71	* for the case where a function is intentionally missing frame pointer setup,
	72	* but otherwise needs objtool/ORC coverage when frame pointers are disabled.
	73	*/
	74	#ifdef CONFIG_FRAME_POINTER
	75	#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
	76	#else
	77	#define STACK_FRAME_NON_STANDARD_FP(func)
	78	#endif
	79
5567c6c3 JT	80	#else /* __ASSEMBLY__ */
5567c6c3 JT	81
8aa8eb2a AC	82	/*
	83	* This macro indicates that the following intra-function call is valid.
	84	* Any non-annotated intra-function call will cause objtool to issue a warning.
	85	*/
	86	#define ANNOTATE_INTRA_FUNCTION_CALL \
	87	999: \
	88	.pushsection .discard.intra_function_calls; \
	89	.long 999b; \
	90	.popsection;
	91
ee819aed JT	92	/*
	93	* In asm, there are two kinds of code: normal C-type callable functions and
	94	* the rest. The normal callable functions can be called by other code, and
	95	* don't do anything unusual with the stack. Such normal callable functions
	96	* are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
	97	* category. In this case, no special debugging annotations are needed because
	98	* objtool can automatically generate the ORC data for the ORC unwinder to read
	99	* at runtime.
	100	*
	101	* Anything which doesn't fall into the above category, such as syscall and
	102	* interrupt handlers, tends to not be called directly by other functions, and
	103	* often does unusual non-C-function-type things with the stack pointer. Such
	104	* code needs to be annotated such that objtool can understand it. The
	105	* following CFI hint macros are for this type of code.
	106	*
	107	* These macros provide hints to objtool about the state of the stack at each
	108	* instruction. Objtool starts from the hints and follows the code flow,
	109	* making automatic CFI adjustments when it sees pushes and pops, filling out
	110	* the debuginfo as necessary. It will also warn if it sees any
	111	* inconsistencies.
	112	*/
	113	.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
	114	.Lunwind_hint_ip_\@:
	115	.pushsection .discard.unwind_hints
	116	/* struct unwind_hint */
	117	.long .Lunwind_hint_ip_\@ - .
	118	.short \sp_offset
	119	.byte \sp_reg
	120	.byte \type
	121	.byte \end
	122	.balign 4
	123	.popsection
	124	.endm
	125
081df943 JP	126	.macro STACK_FRAME_NON_STANDARD func:req
	127	.pushsection .discard.func_stack_frame_non_standard, "aw"
	128	.long \func - .
	129	.popsection
	130	.endm
	131
5567c6c3 JT	132	#endif /* __ASSEMBLY__ */
5567c6c3 JT	133
9a99417a JP	134	#else /* !CONFIG_STACK_VALIDATION */
9a99417a JP	135
ee819aed JT	136	#ifndef __ASSEMBLY__
	137
	138	#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
	139	"\n\t"
9a99417a	140	#define STACK_FRAME_NON_STANDARD(func)
e028c4f7	141	#define STACK_FRAME_NON_STANDARD_FP(func)
ee819aed	142	#else
8aa8eb2a	143	#define ANNOTATE_INTRA_FUNCTION_CALL
ee819aed JT	144	.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
ee819aed JT	145	.endm
081df943 JP	146	.macro STACK_FRAME_NON_STANDARD func:req
081df943 JP	147	.endm
ee819aed	148	#endif
9a99417a JP	149
	150	#endif /* CONFIG_STACK_VALIDATION */
	151
00089c04	152	#endif /* _LINUX_OBJTOOL_H */