forked from mirrors/linux
b735bd3e68
The ORC metadata generated for UNWIND_HINT_FUNC isn't actually very func-like. With certain usages it can cause stack state mismatches because it doesn't set the return address (CFI_RA). Also, users of UNWIND_HINT_RET_OFFSET no longer need to set a custom return stack offset. Instead they just need to specify a func-like situation, so the current ret_offset code is hacky for no good reason. Solve both problems by simplifying the RET_OFFSET handling and converting it into a more useful UNWIND_HINT_FUNC. If we end up needing the old 'ret_offset' functionality again in the future, we should be able to support it pretty easily with the addition of a custom 'sp_offset' in UNWIND_HINT_FUNC. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/db9d1f5d79dddfbb3725ef6d8ec3477ad199948d.1611263462.git.jpoimboe@redhat.com
140 lines
4.4 KiB
C
140 lines
4.4 KiB
C
/* 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 */
|