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linux/arch/x86/include/asm/asm.h
Peter Zijlstra 4b5305decc x86/extable: Extend extable functionality 
In order to remove further .fixup usage, extend the extable
infrastructure to take additional information from the extable entry
sites.

Specifically add _ASM_EXTABLE_TYPE_REG() and EX_TYPE_IMM_REG that
extend the existing _ASM_EXTABLE_TYPE() by taking an additional
register argument and encoding that and an s16 immediate into the
existing s32 type field. This limits the actual types to the first
byte, 255 seem plenty.

Also add a few flags into the type word, specifically CLEAR_AX and
CLEAR_DX which clear the return and extended return register.

Notes:
 - due to the % in our register names it's hard to make it more
   generally usable as arm64 did.
 - the s16 is far larger than used in these patches, future extentions
   can easily shrink this to get more bits.
 - without the bitfield fix this will not compile, because: 0xFF > -1
   and we can't even extract the TYPE field.

[nathanchance: Build fix for clang-lto builds:
 https://lkml.kernel.org/r/20211210234953.3420108-1-nathan@kernel.org
]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20211110101325.303890153@infradead.org
2021-12-11 09:09:46 +01:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_ASM_H
#define _ASM_X86_ASM_H
#ifdef __ASSEMBLY__
# define __ASM_FORM(x, ...) x,## __VA_ARGS__
# define __ASM_FORM_RAW(x, ...) x,## __VA_ARGS__
# define __ASM_FORM_COMMA(x, ...) x,## __VA_ARGS__,
# define __ASM_REGPFX %
#else
#include <linux/stringify.h>
# define __ASM_FORM(x, ...) " " __stringify(x,##__VA_ARGS__) " "
# define __ASM_FORM_RAW(x, ...) __stringify(x,##__VA_ARGS__)
# define __ASM_FORM_COMMA(x, ...) " " __stringify(x,##__VA_ARGS__) ","
# define __ASM_REGPFX %%
#endif
#define _ASM_BYTES(x, ...) __ASM_FORM(.byte x,##__VA_ARGS__ ;)
#ifndef __x86_64__
/* 32 bit */
# define __ASM_SEL(a,b) __ASM_FORM(a)
# define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(a)
#else
/* 64 bit */
# define __ASM_SEL(a,b) __ASM_FORM(b)
# define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(b)
#endif
#define __ASM_SIZE(inst, ...) __ASM_SEL(inst##l##__VA_ARGS__, \
inst##q##__VA_ARGS__)
#define __ASM_REG(reg) __ASM_SEL_RAW(e##reg, r##reg)
#define _ASM_PTR __ASM_SEL(.long, .quad)
#define _ASM_ALIGN __ASM_SEL(.balign 4, .balign 8)
#define _ASM_MOV __ASM_SIZE(mov)
#define _ASM_INC __ASM_SIZE(inc)
#define _ASM_DEC __ASM_SIZE(dec)
#define _ASM_ADD __ASM_SIZE(add)
#define _ASM_SUB __ASM_SIZE(sub)
#define _ASM_XADD __ASM_SIZE(xadd)
#define _ASM_MUL __ASM_SIZE(mul)
#define _ASM_AX __ASM_REG(ax)
#define _ASM_BX __ASM_REG(bx)
#define _ASM_CX __ASM_REG(cx)
#define _ASM_DX __ASM_REG(dx)
#define _ASM_SP __ASM_REG(sp)
#define _ASM_BP __ASM_REG(bp)
#define _ASM_SI __ASM_REG(si)
#define _ASM_DI __ASM_REG(di)
/* Adds a (%rip) suffix on 64 bits only; for immediate memory references */
#define _ASM_RIP(x) __ASM_SEL_RAW(x, x (__ASM_REGPFX rip))
#ifndef __x86_64__
/* 32 bit */
#define _ASM_ARG1 _ASM_AX
#define _ASM_ARG2 _ASM_DX
#define _ASM_ARG3 _ASM_CX
#define _ASM_ARG1L eax
#define _ASM_ARG2L edx
#define _ASM_ARG3L ecx
#define _ASM_ARG1W ax
#define _ASM_ARG2W dx
#define _ASM_ARG3W cx
#define _ASM_ARG1B al
#define _ASM_ARG2B dl
#define _ASM_ARG3B cl
#else
/* 64 bit */
#define _ASM_ARG1 _ASM_DI
#define _ASM_ARG2 _ASM_SI
#define _ASM_ARG3 _ASM_DX
#define _ASM_ARG4 _ASM_CX
#define _ASM_ARG5 r8
#define _ASM_ARG6 r9
#define _ASM_ARG1Q rdi
#define _ASM_ARG2Q rsi
#define _ASM_ARG3Q rdx
#define _ASM_ARG4Q rcx
#define _ASM_ARG5Q r8
#define _ASM_ARG6Q r9
#define _ASM_ARG1L edi
#define _ASM_ARG2L esi
#define _ASM_ARG3L edx
#define _ASM_ARG4L ecx
#define _ASM_ARG5L r8d
#define _ASM_ARG6L r9d
#define _ASM_ARG1W di
#define _ASM_ARG2W si
#define _ASM_ARG3W dx
#define _ASM_ARG4W cx
#define _ASM_ARG5W r8w
#define _ASM_ARG6W r9w
#define _ASM_ARG1B dil
#define _ASM_ARG2B sil
#define _ASM_ARG3B dl
#define _ASM_ARG4B cl
#define _ASM_ARG5B r8b
#define _ASM_ARG6B r9b
#endif
/*
* Macros to generate condition code outputs from inline assembly,
* The output operand must be type "bool".
*/
#ifdef __GCC_ASM_FLAG_OUTPUTS__
# define CC_SET(c) "\n\t/* output condition code " #c "*/\n"
# define CC_OUT(c) "=@cc" #c
#else
# define CC_SET(c) "\n\tset" #c " %[_cc_" #c "]\n"
# define CC_OUT(c) [_cc_ ## c] "=qm"
#endif
#ifdef __KERNEL__
# include <asm/extable_fixup_types.h>
/* Exception table entry */
#ifdef __ASSEMBLY__
# define _ASM_EXTABLE_TYPE(from, to, type) \
.pushsection "__ex_table","a" ; \
.balign 4 ; \
.long (from) - . ; \
.long (to) - . ; \
.long type ; \
.popsection
# ifdef CONFIG_KPROBES
# define _ASM_NOKPROBE(entry) \
.pushsection "_kprobe_blacklist","aw" ; \
_ASM_ALIGN ; \
_ASM_PTR (entry); \
.popsection
# else
# define _ASM_NOKPROBE(entry)
# endif
#else /* ! __ASSEMBLY__ */
# define DEFINE_EXTABLE_TYPE_REG \
".macro extable_type_reg type:req reg:req\n" \
".set found, 0\n" \
".set regnr, 0\n" \
".irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n" \
".ifc \\reg, %%\\rs\n" \
".set found, found+1\n" \
".long \\type + (regnr << 8)\n" \
".endif\n" \
".set regnr, regnr+1\n" \
".endr\n" \
".set regnr, 0\n" \
".irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n" \
".ifc \\reg, %%\\rs\n" \
".set found, found+1\n" \
".long \\type + (regnr << 8)\n" \
".endif\n" \
".set regnr, regnr+1\n" \
".endr\n" \
".if (found != 1)\n" \
".error \"extable_type_reg: bad register argument\"\n" \
".endif\n" \
".endm\n"
# define UNDEFINE_EXTABLE_TYPE_REG \
".purgem extable_type_reg\n"
# define _ASM_EXTABLE_TYPE(from, to, type) \
" .pushsection \"__ex_table\",\"a\"\n" \
" .balign 4\n" \
" .long (" #from ") - .\n" \
" .long (" #to ") - .\n" \
" .long " __stringify(type) " \n" \
" .popsection\n"
# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg) \
" .pushsection \"__ex_table\",\"a\"\n" \
" .balign 4\n" \
" .long (" #from ") - .\n" \
" .long (" #to ") - .\n" \
DEFINE_EXTABLE_TYPE_REG \
"extable_type_reg reg=" __stringify(reg) ", type=" __stringify(type) " \n"\
UNDEFINE_EXTABLE_TYPE_REG \
" .popsection\n"
/* For C file, we already have NOKPROBE_SYMBOL macro */
/*
* This output constraint should be used for any inline asm which has a "call"
* instruction. Otherwise the asm may be inserted before the frame pointer
* gets set up by the containing function. If you forget to do this, objtool
* may print a "call without frame pointer save/setup" warning.
*/
register unsigned long current_stack_pointer asm(_ASM_SP);
#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif /* __ASSEMBLY__ */
#define _ASM_EXTABLE(from, to) \
_ASM_EXTABLE_TYPE(from, to, EX_TYPE_DEFAULT)
#define _ASM_EXTABLE_UA(from, to) \
_ASM_EXTABLE_TYPE(from, to, EX_TYPE_UACCESS)
#define _ASM_EXTABLE_CPY(from, to) \
_ASM_EXTABLE_TYPE(from, to, EX_TYPE_COPY)
#define _ASM_EXTABLE_FAULT(from, to) \
_ASM_EXTABLE_TYPE(from, to, EX_TYPE_FAULT)
#endif /* __KERNEL__ */
#endif /* _ASM_X86_ASM_H */
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