powerpc: Use gas sections for arranging exception vectors
Use assembler sections of fixed size and location to arrange the 64-bit Book3S exception vector code (64-bit Book3E also uses it in head_64.S for 0x0..0x100). This allows better flexibility in arranging exception code and hiding unimportant details behind macros. Gas sections can be a bit painful to use this way, mainly because the assembler does not know where they will be finally linked. Taking absolute addresses requires a bit of trickery for example, but it can be hidden behind macros for the most part. Generated code is mostly the same except locations, offsets, alignments. The "+ 0x2" is only required for the trap number / kvm exit number, which gets loaded as a constant into a register. Previously, code also used + 0x2 for label names, but we changed to using "H" to distinguish HV case for that. Remove the last vestiges of that. __after_prom_start is taking absolute address of a label in another fixed section. Newer toolchains seemed to compile this okay, but older ones do not. FIXED_SYMBOL_ABS_ADDR is more foolproof, it just takes an additional line to define. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Cette révision appartient à :
Nicholas Piggin
révisé par
Michael Ellerman
Michael Ellerman
Parent
573819e343
révision
57f266497d
@@ -3,28 +3,218 @@
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#include <asm/cache.h>
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#define EXC_REAL_BEGIN(name, start, end) \
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. = start ; \
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.global exc_real_##start##_##name ; \
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exc_real_##start##_##name:
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/*
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* We can't do CPP stringification and concatination directly into the section
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* name for some reason, so these macros can do it for us.
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*/
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.macro define_ftsec name
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.section ".head.text.\name\()","ax",@progbits
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.endm
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.macro define_data_ftsec name
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.section ".head.data.\name\()","a",@progbits
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.endm
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.macro use_ftsec name
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.section ".head.text.\name\()"
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.endm
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#define EXC_REAL_END(name, start, end)
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/*
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* Fixed (location) sections are used by opening fixed sections and emitting
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* fixed section entries into them before closing them. Multiple fixed sections
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* can be open at any time.
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*
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* Each fixed section created in a .S file must have corresponding linkage
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* directives including location, added to arch/powerpc/kernel/vmlinux.lds.S
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*
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* For each fixed section, code is generated into it in the order which it
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* appears in the source. Fixed section entries can be placed at a fixed
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* location within the section using _LOCATION postifx variants. These must
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* be ordered according to their relative placements within the section.
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*
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* OPEN_FIXED_SECTION(section_name, start_address, end_address)
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* FIXED_SECTION_ENTRY_BEGIN(section_name, label1)
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*
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* USE_FIXED_SECTION(section_name)
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* label3:
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* li r10,128
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* mv r11,r10
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* FIXED_SECTION_ENTRY_BEGIN_LOCATION(section_name, label2, start_address)
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* FIXED_SECTION_ENTRY_END_LOCATION(section_name, label2, end_address)
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* CLOSE_FIXED_SECTION(section_name)
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*
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* ZERO_FIXED_SECTION can be used to emit zeroed data.
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*
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* Troubleshooting:
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* - If the build dies with "Error: attempt to move .org backwards" at
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* CLOSE_FIXED_SECTION() or elsewhere, there may be something
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* unexpected being added there. Remove the '. = x_len' line, rebuild, and
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* check what is pushing the section down.
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* - If the build dies in linking, check arch/powerpc/kernel/vmlinux.lds.S
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* for instructions.
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* - If the kernel crashes or hangs in very early boot, it could be linker
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* stubs at the start of the main text.
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*/
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#define OPEN_FIXED_SECTION(sname, start, end) \
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sname##_start = (start); \
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sname##_end = (end); \
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sname##_len = (end) - (start); \
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define_ftsec sname; \
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. = 0x0; \
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start_##sname:
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#define OPEN_TEXT_SECTION(start) \
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text_start = (start); \
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.section ".text","ax",@progbits; \
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. = 0x0; \
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start_text:
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#define ZERO_FIXED_SECTION(sname, start, end) \
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sname##_start = (start); \
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sname##_end = (end); \
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sname##_len = (end) - (start); \
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define_data_ftsec sname; \
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. = 0x0; \
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. = sname##_len;
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#define USE_FIXED_SECTION(sname) \
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fs_label = start_##sname; \
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fs_start = sname##_start; \
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use_ftsec sname;
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#define USE_TEXT_SECTION() \
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fs_label = start_text; \
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fs_start = text_start; \
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.text
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#define CLOSE_FIXED_SECTION(sname) \
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USE_FIXED_SECTION(sname); \
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. = sname##_len; \
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end_##sname:
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#define __FIXED_SECTION_ENTRY_BEGIN(sname, name, __align) \
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USE_FIXED_SECTION(sname); \
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.align __align; \
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.global name; \
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name:
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#define FIXED_SECTION_ENTRY_BEGIN(sname, name) \
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__FIXED_SECTION_ENTRY_BEGIN(sname, name, 0)
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#define FIXED_SECTION_ENTRY_BEGIN_LOCATION(sname, name, start) \
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USE_FIXED_SECTION(sname); \
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name##_start = (start); \
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.if (start) < sname##_start; \
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.error "Fixed section underflow"; \
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.abort; \
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.endif; \
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. = (start) - sname##_start; \
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.global name; \
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name:
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#define FIXED_SECTION_ENTRY_END_LOCATION(sname, name, end) \
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.if (end) > sname##_end; \
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.error "Fixed section overflow"; \
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.abort; \
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.endif; \
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.if (. - name > end - name##_start); \
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.error "Fixed entry overflow"; \
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.abort; \
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.endif; \
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. = ((end) - sname##_start); \
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/*
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* These macros are used to change symbols in other fixed sections to be
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* absolute or related to our current fixed section.
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*
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* - DEFINE_FIXED_SYMBOL / FIXED_SYMBOL_ABS_ADDR is used to find the
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* absolute address of a symbol within a fixed section, from any section.
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*
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* - ABS_ADDR is used to find the absolute address of any symbol, from within
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* a fixed section.
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*/
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#define DEFINE_FIXED_SYMBOL(label) \
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label##_absolute = (label - fs_label + fs_start)
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#define FIXED_SYMBOL_ABS_ADDR(label) \
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(label##_absolute)
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#define ABS_ADDR(label) (label - fs_label + fs_start)
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/*
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* Following are the BOOK3S exception handler helper macros.
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* Handlers come in a number of types, and each type has a number of varieties.
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*
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* EXC_REAL_* - real, unrelocated exception vectors
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* EXC_VIRT_* - virt (AIL), unrelocated exception vectors
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* TRAMP_REAL_* - real, unrelocated helpers (virt can call these)
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* TRAMP_VIRT_* - virt, unreloc helpers (in practice, real can use)
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* TRAMP_KVM - KVM handlers that get put into real, unrelocated
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* EXC_COMMON_* - virt, relocated common handlers
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*
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* The EXC handlers are given a name, and branch to name_common, or the
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* appropriate KVM or masking function. Vector handler verieties are as
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* follows:
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*
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* EXC_{REAL|VIRT}_BEGIN/END - used to open-code the exception
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*
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* EXC_{REAL|VIRT} - standard exception
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*
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* EXC_{REAL|VIRT}_suffix
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* where _suffix is:
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* - _MASKABLE - maskable exception
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* - _OOL - out of line with trampoline to common handler
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* - _HV - HV exception
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*
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* There can be combinations, e.g., EXC_VIRT_OOL_MASKABLE_HV
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*
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* The one unusual case is __EXC_REAL_OOL_HV_DIRECT, which is
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* an OOL vector that branches to a specified handler rather than the usual
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* trampoline that goes to common. It, and other underscore macros, should
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* be used with care.
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*
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* KVM handlers come in the following verieties:
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* TRAMP_KVM
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* TRAMP_KVM_SKIP
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* TRAMP_KVM_HV
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* TRAMP_KVM_HV_SKIP
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*
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* COMMON handlers come in the following verieties:
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* EXC_COMMON_BEGIN/END - used to open-code the handler
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* EXC_COMMON
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* EXC_COMMON_ASYNC
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* EXC_COMMON_HV
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*
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* TRAMP_REAL and TRAMP_VIRT can be used with BEGIN/END. KVM
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* and OOL handlers are implemented as types of TRAMP and TRAMP_VIRT handlers.
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*/
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#define EXC_REAL_BEGIN(name, start, end) \
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FIXED_SECTION_ENTRY_BEGIN_LOCATION(real_vectors, exc_real_##start##_##name, start)
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#define EXC_REAL_END(name, start, end) \
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FIXED_SECTION_ENTRY_END_LOCATION(real_vectors, exc_real_##start##_##name, end)
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#define EXC_VIRT_BEGIN(name, start, end) \
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. = start ; \
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.global exc_virt_##start##_##name ; \
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exc_virt_##start##_##name:
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FIXED_SECTION_ENTRY_BEGIN_LOCATION(virt_vectors, exc_virt_##start##_##name, start)
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#define EXC_VIRT_END(name, start, end)
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#define EXC_VIRT_END(name, start, end) \
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FIXED_SECTION_ENTRY_END_LOCATION(virt_vectors, exc_virt_##start##_##name, end)
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#define EXC_COMMON_BEGIN(name) \
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USE_TEXT_SECTION(); \
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.align 7; \
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.global name; \
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DEFINE_FIXED_SYMBOL(name); \
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name:
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#define TRAMP_REAL_BEGIN(name) \
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.global name ; \
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name:
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FIXED_SECTION_ENTRY_BEGIN(real_trampolines, name)
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#define TRAMP_VIRT_BEGIN(name) \
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FIXED_SECTION_ENTRY_BEGIN(virt_trampolines, name)
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#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
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#define TRAMP_KVM_BEGIN(name) \
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@@ -33,9 +223,13 @@ name:
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#define TRAMP_KVM_BEGIN(name)
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#endif
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#define EXC_REAL_NONE(start, end)
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#define EXC_REAL_NONE(start, end) \
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FIXED_SECTION_ENTRY_BEGIN_LOCATION(real_vectors, exc_real_##start##_##unused, start); \
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FIXED_SECTION_ENTRY_END_LOCATION(real_vectors, exc_real_##start##_##unused, end)
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#define EXC_VIRT_NONE(start, end)
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#define EXC_VIRT_NONE(start, end) \
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FIXED_SECTION_ENTRY_BEGIN_LOCATION(virt_vectors, exc_virt_##start##_##unused, start); \
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FIXED_SECTION_ENTRY_END_LOCATION(virt_vectors, exc_virt_##start##_##unused, end);
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#define EXC_REAL(name, start, end) \
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@@ -77,6 +271,10 @@ name:
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TRAMP_REAL_BEGIN(tramp_real_##name); \
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STD_EXCEPTION_PSERIES_OOL(vec, name##_common); \
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#define EXC_REAL_OOL(name, start, end) \
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__EXC_REAL_OOL(name, start, end); \
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__TRAMP_REAL_REAL_OOL(name, start);
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#define __EXC_REAL_OOL_MASKABLE(name, start, end) \
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__EXC_REAL_OOL(name, start, end);
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@@ -84,6 +282,10 @@ name:
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TRAMP_REAL_BEGIN(tramp_real_##name); \
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MASKABLE_EXCEPTION_PSERIES_OOL(vec, name##_common); \
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#define EXC_REAL_OOL_MASKABLE(name, start, end) \
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__EXC_REAL_OOL_MASKABLE(name, start, end); \
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__TRAMP_REAL_REAL_OOL_MASKABLE(name, start);
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#define __EXC_REAL_OOL_HV_DIRECT(name, start, end, handler) \
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EXC_REAL_BEGIN(name, start, end); \
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__OOL_EXCEPTION(start, label, handler); \
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@@ -96,6 +298,10 @@ name:
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TRAMP_REAL_BEGIN(tramp_real_##name); \
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STD_EXCEPTION_HV_OOL(vec, name##_common); \
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#define EXC_REAL_OOL_HV(name, start, end) \
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__EXC_REAL_OOL_HV(name, start, end); \
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__TRAMP_REAL_REAL_OOL_HV(name, start);
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#define __EXC_REAL_OOL_MASKABLE_HV(name, start, end) \
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__EXC_REAL_OOL(name, start, end);
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@@ -103,36 +309,56 @@ name:
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TRAMP_REAL_BEGIN(tramp_real_##name); \
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MASKABLE_EXCEPTION_HV_OOL(vec, name##_common); \
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#define EXC_REAL_OOL_MASKABLE_HV(name, start, end) \
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__EXC_REAL_OOL_MASKABLE_HV(name, start, end); \
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__TRAMP_REAL_REAL_OOL_MASKABLE_HV(name, start);
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#define __EXC_VIRT_OOL(name, start, end) \
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EXC_VIRT_BEGIN(name, start, end); \
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__OOL_EXCEPTION(start, label, tramp_virt_##name); \
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EXC_VIRT_END(name, start, end);
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#define __TRAMP_REAL_VIRT_OOL(name, realvec) \
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TRAMP_REAL_BEGIN(tramp_virt_##name); \
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TRAMP_VIRT_BEGIN(tramp_virt_##name); \
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STD_RELON_EXCEPTION_PSERIES_OOL(realvec, name##_common); \
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#define EXC_VIRT_OOL(name, start, end, realvec) \
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__EXC_VIRT_OOL(name, start, end); \
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__TRAMP_REAL_VIRT_OOL(name, realvec);
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#define __EXC_VIRT_OOL_MASKABLE(name, start, end) \
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__EXC_VIRT_OOL(name, start, end);
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#define __TRAMP_REAL_VIRT_OOL_MASKABLE(name, realvec) \
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TRAMP_REAL_BEGIN(tramp_virt_##name); \
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TRAMP_VIRT_BEGIN(tramp_virt_##name); \
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MASKABLE_RELON_EXCEPTION_PSERIES_OOL(realvec, name##_common); \
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#define EXC_VIRT_OOL_MASKABLE(name, start, end, realvec) \
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__EXC_VIRT_OOL_MASKABLE(name, start, end); \
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__TRAMP_REAL_VIRT_OOL_MASKABLE(name, realvec);
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#define __EXC_VIRT_OOL_HV(name, start, end) \
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__EXC_VIRT_OOL(name, start, end);
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#define __TRAMP_REAL_VIRT_OOL_HV(name, realvec) \
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TRAMP_REAL_BEGIN(tramp_virt_##name); \
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TRAMP_VIRT_BEGIN(tramp_virt_##name); \
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STD_RELON_EXCEPTION_HV_OOL(realvec, name##_common); \
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#define EXC_VIRT_OOL_HV(name, start, end, realvec) \
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__EXC_VIRT_OOL_HV(name, start, end); \
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__TRAMP_REAL_VIRT_OOL_HV(name, realvec);
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#define __EXC_VIRT_OOL_MASKABLE_HV(name, start, end) \
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__EXC_VIRT_OOL(name, start, end);
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#define __TRAMP_REAL_VIRT_OOL_MASKABLE_HV(name, realvec) \
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TRAMP_REAL_BEGIN(tramp_virt_##name); \
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TRAMP_VIRT_BEGIN(tramp_virt_##name); \
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MASKABLE_RELON_EXCEPTION_HV_OOL(realvec, name##_common); \
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#define EXC_VIRT_OOL_MASKABLE_HV(name, start, end, realvec) \
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__EXC_VIRT_OOL_MASKABLE_HV(name, start, end); \
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__TRAMP_REAL_VIRT_OOL_MASKABLE_HV(name, realvec);
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#define TRAMP_KVM(area, n) \
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TRAMP_KVM_BEGIN(do_kvm_##n); \
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KVM_HANDLER(area, EXC_STD, n); \
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@@ -141,6 +367,9 @@ name:
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TRAMP_KVM_BEGIN(do_kvm_##n); \
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KVM_HANDLER_SKIP(area, EXC_STD, n); \
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/*
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* HV variant exceptions get the 0x2 bit added to their trap number.
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*/
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#define TRAMP_KVM_HV(area, n) \
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TRAMP_KVM_BEGIN(do_kvm_H##n); \
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KVM_HANDLER(area, EXC_HV, n + 0x2); \
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