linux/arch/powerpc/include/asm/feature-fixups.h
Michael Ellerman c0337288ab powerpc: Ensure the else case of feature sections will fit
When we create an alternative feature section, the else case must be the
same size or smaller than the body. This is because when we patch the
else case in we just overwrite the body, so there must be room.

Up to now we just did this by inspection, but it's quite easy to enforce
it in the assembler, so we should.

The only change is to add the ifgt block, but that effects the alignment
of the tabs and so the whole macro is modified.

Also add a test, but #if 0 it because we don't want to break the build.
Anyone who's modifying the feature macros should enable the test.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-01-21 14:08:33 +11:00

175 lines
6.3 KiB
C

#ifndef __ASM_POWERPC_FEATURE_FIXUPS_H
#define __ASM_POWERPC_FEATURE_FIXUPS_H
/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
/*
* Feature section common macros
*
* Note that the entries now contain offsets between the table entry
* and the code rather than absolute code pointers in order to be
* useable with the vdso shared library. There is also an assumption
* that values will be negative, that is, the fixup table has to be
* located after the code it fixes up.
*/
#if defined(CONFIG_PPC64) && !defined(__powerpc64__)
/* 64 bits kernel, 32 bits code (ie. vdso32) */
#define FTR_ENTRY_LONG .llong
#define FTR_ENTRY_OFFSET .long 0xffffffff; .long
#elif defined(CONFIG_PPC64)
#define FTR_ENTRY_LONG .llong
#define FTR_ENTRY_OFFSET .llong
#else
#define FTR_ENTRY_LONG .long
#define FTR_ENTRY_OFFSET .long
#endif
#define START_FTR_SECTION(label) label##1:
#define FTR_SECTION_ELSE_NESTED(label) \
label##2: \
.pushsection __ftr_alt_##label,"a"; \
.align 2; \
label##3:
#define MAKE_FTR_SECTION_ENTRY(msk, val, label, sect) \
label##4: \
.popsection; \
.pushsection sect,"a"; \
.align 3; \
label##5: \
FTR_ENTRY_LONG msk; \
FTR_ENTRY_LONG val; \
FTR_ENTRY_OFFSET label##1b-label##5b; \
FTR_ENTRY_OFFSET label##2b-label##5b; \
FTR_ENTRY_OFFSET label##3b-label##5b; \
FTR_ENTRY_OFFSET label##4b-label##5b; \
.ifgt (label##4b-label##3b)-(label##2b-label##1b); \
.error "Feature section else case larger than body"; \
.endif; \
.popsection;
/* CPU feature dependent sections */
#define BEGIN_FTR_SECTION_NESTED(label) START_FTR_SECTION(label)
#define BEGIN_FTR_SECTION START_FTR_SECTION(97)
#define END_FTR_SECTION_NESTED(msk, val, label) \
FTR_SECTION_ELSE_NESTED(label) \
MAKE_FTR_SECTION_ENTRY(msk, val, label, __ftr_fixup)
#define END_FTR_SECTION(msk, val) \
END_FTR_SECTION_NESTED(msk, val, 97)
#define END_FTR_SECTION_IFSET(msk) END_FTR_SECTION((msk), (msk))
#define END_FTR_SECTION_IFCLR(msk) END_FTR_SECTION((msk), 0)
/* CPU feature sections with alternatives, use BEGIN_FTR_SECTION to start */
#define FTR_SECTION_ELSE FTR_SECTION_ELSE_NESTED(97)
#define ALT_FTR_SECTION_END_NESTED(msk, val, label) \
MAKE_FTR_SECTION_ENTRY(msk, val, label, __ftr_fixup)
#define ALT_FTR_SECTION_END_NESTED_IFSET(msk, label) \
ALT_FTR_SECTION_END_NESTED(msk, msk, label)
#define ALT_FTR_SECTION_END_NESTED_IFCLR(msk, label) \
ALT_FTR_SECTION_END_NESTED(msk, 0, label)
#define ALT_FTR_SECTION_END(msk, val) \
ALT_FTR_SECTION_END_NESTED(msk, val, 97)
#define ALT_FTR_SECTION_END_IFSET(msk) \
ALT_FTR_SECTION_END_NESTED_IFSET(msk, 97)
#define ALT_FTR_SECTION_END_IFCLR(msk) \
ALT_FTR_SECTION_END_NESTED_IFCLR(msk, 97)
/* MMU feature dependent sections */
#define BEGIN_MMU_FTR_SECTION_NESTED(label) START_FTR_SECTION(label)
#define BEGIN_MMU_FTR_SECTION START_FTR_SECTION(97)
#define END_MMU_FTR_SECTION_NESTED(msk, val, label) \
FTR_SECTION_ELSE_NESTED(label) \
MAKE_FTR_SECTION_ENTRY(msk, val, label, __mmu_ftr_fixup)
#define END_MMU_FTR_SECTION(msk, val) \
END_MMU_FTR_SECTION_NESTED(msk, val, 97)
#define END_MMU_FTR_SECTION_IFSET(msk) END_MMU_FTR_SECTION((msk), (msk))
#define END_MMU_FTR_SECTION_IFCLR(msk) END_MMU_FTR_SECTION((msk), 0)
/* MMU feature sections with alternatives, use BEGIN_FTR_SECTION to start */
#define MMU_FTR_SECTION_ELSE_NESTED(label) FTR_SECTION_ELSE_NESTED(label)
#define MMU_FTR_SECTION_ELSE MMU_FTR_SECTION_ELSE_NESTED(97)
#define ALT_MMU_FTR_SECTION_END_NESTED(msk, val, label) \
MAKE_FTR_SECTION_ENTRY(msk, val, label, __mmu_ftr_fixup)
#define ALT_MMU_FTR_SECTION_END_NESTED_IFSET(msk, label) \
ALT_MMU_FTR_SECTION_END_NESTED(msk, msk, label)
#define ALT_MMU_FTR_SECTION_END_NESTED_IFCLR(msk, label) \
ALT_MMU_FTR_SECTION_END_NESTED(msk, 0, label)
#define ALT_MMU_FTR_SECTION_END(msk, val) \
ALT_MMU_FTR_SECTION_END_NESTED(msk, val, 97)
#define ALT_MMU_FTR_SECTION_END_IFSET(msk) \
ALT_MMU_FTR_SECTION_END_NESTED_IFSET(msk, 97)
#define ALT_MMU_FTR_SECTION_END_IFCLR(msk) \
ALT_MMU_FTR_SECTION_END_NESTED_IFCLR(msk, 97)
/* Firmware feature dependent sections */
#define BEGIN_FW_FTR_SECTION_NESTED(label) START_FTR_SECTION(label)
#define BEGIN_FW_FTR_SECTION START_FTR_SECTION(97)
#define END_FW_FTR_SECTION_NESTED(msk, val, label) \
FTR_SECTION_ELSE_NESTED(label) \
MAKE_FTR_SECTION_ENTRY(msk, val, label, __fw_ftr_fixup)
#define END_FW_FTR_SECTION(msk, val) \
END_FW_FTR_SECTION_NESTED(msk, val, 97)
#define END_FW_FTR_SECTION_IFSET(msk) END_FW_FTR_SECTION((msk), (msk))
#define END_FW_FTR_SECTION_IFCLR(msk) END_FW_FTR_SECTION((msk), 0)
/* Firmware feature sections with alternatives */
#define FW_FTR_SECTION_ELSE_NESTED(label) FTR_SECTION_ELSE_NESTED(label)
#define FW_FTR_SECTION_ELSE FTR_SECTION_ELSE_NESTED(97)
#define ALT_FW_FTR_SECTION_END_NESTED(msk, val, label) \
MAKE_FTR_SECTION_ENTRY(msk, val, label, __fw_ftr_fixup)
#define ALT_FW_FTR_SECTION_END_NESTED_IFSET(msk, label) \
ALT_FW_FTR_SECTION_END_NESTED(msk, msk, label)
#define ALT_FW_FTR_SECTION_END_NESTED_IFCLR(msk, label) \
ALT_FW_FTR_SECTION_END_NESTED(msk, 0, label)
#define ALT_FW_FTR_SECTION_END(msk, val) \
ALT_FW_FTR_SECTION_END_NESTED(msk, val, 97)
#define ALT_FW_FTR_SECTION_END_IFSET(msk) \
ALT_FW_FTR_SECTION_END_NESTED_IFSET(msk, 97)
#define ALT_FW_FTR_SECTION_END_IFCLR(msk) \
ALT_FW_FTR_SECTION_END_NESTED_IFCLR(msk, 97)
#ifndef __ASSEMBLY__
#define ASM_MMU_FTR_IF(section_if, section_else, msk, val) \
stringify_in_c(BEGIN_MMU_FTR_SECTION) \
section_if "; " \
stringify_in_c(MMU_FTR_SECTION_ELSE) \
section_else "; " \
stringify_in_c(ALT_MMU_FTR_SECTION_END((msk), (val)))
#define ASM_MMU_FTR_IFSET(section_if, section_else, msk) \
ASM_MMU_FTR_IF(section_if, section_else, (msk), (msk))
#define ASM_MMU_FTR_IFCLR(section_if, section_else, msk) \
ASM_MMU_FTR_IF(section_if, section_else, (msk), 0)
#endif /* __ASSEMBLY__ */
/* LWSYNC feature sections */
#define START_LWSYNC_SECTION(label) label##1:
#define MAKE_LWSYNC_SECTION_ENTRY(label, sect) \
label##2: \
.pushsection sect,"a"; \
.align 2; \
label##3: \
FTR_ENTRY_OFFSET label##1b-label##3b; \
.popsection;
#endif /* __ASM_POWERPC_FEATURE_FIXUPS_H */