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/* 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
#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)
#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 */
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