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Diffstat (limited to 'arch/powerpc/include/asm/head-64.h')
| -rw-r--r-- | arch/powerpc/include/asm/head-64.h | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/head-64.h b/arch/powerpc/include/asm/head-64.h new file mode 100644 index 000000000..d73153b02 --- /dev/null +++ b/arch/powerpc/include/asm/head-64.h @@ -0,0 +1,172 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_HEAD_64_H +#define _ASM_POWERPC_HEAD_64_H + +#include <asm/cache.h> + +#ifdef __ASSEMBLY__ +/* + * We can't do CPP stringification and concatination directly into the section + * name for some reason, so these macros can do it for us. + */ +.macro define_ftsec name + .section ".head.text.\name\()","ax",@progbits +.endm +.macro define_data_ftsec name + .section ".head.data.\name\()","a",@progbits +.endm +.macro use_ftsec name + .section ".head.text.\name\()","ax",@progbits +.endm + +/* + * Fixed (location) sections are used by opening fixed sections and emitting + * fixed section entries into them before closing them. Multiple fixed sections + * can be open at any time. + * + * Each fixed section created in a .S file must have corresponding linkage + * directives including location, added to arch/powerpc/kernel/vmlinux.lds.S + * + * For each fixed section, code is generated into it in the order which it + * appears in the source. Fixed section entries can be placed at a fixed + * location within the section using _LOCATION postifx variants. These must + * be ordered according to their relative placements within the section. + * + * OPEN_FIXED_SECTION(section_name, start_address, end_address) + * FIXED_SECTION_ENTRY_BEGIN(section_name, label1) + * + * USE_FIXED_SECTION(section_name) + * label3: + * li r10,128 + * mv r11,r10 + + * FIXED_SECTION_ENTRY_BEGIN_LOCATION(section_name, label2, start_address, size) + * FIXED_SECTION_ENTRY_END_LOCATION(section_name, label2, start_address, size) + * CLOSE_FIXED_SECTION(section_name) + * + * ZERO_FIXED_SECTION can be used to emit zeroed data. + * + * Troubleshooting: + * - If the build dies with "Error: attempt to move .org backwards" at + * CLOSE_FIXED_SECTION() or elsewhere, there may be something + * unexpected being added there. Remove the '. = x_len' line, rebuild, and + * check what is pushing the section down. + * - If the build dies in linking, check arch/powerpc/tools/head_check.sh + * comments. + * - If the kernel crashes or hangs in very early boot, it could be linker + * stubs at the start of the main text. + */ + +#define OPEN_FIXED_SECTION(sname, start, end) \ + sname##_start = (start); \ + sname##_end = (end); \ + sname##_len = (end) - (start); \ + define_ftsec sname; \ + . = 0x0; \ +start_##sname: + +/* + * .linker_stub_catch section is used to catch linker stubs from being + * inserted in our .text section, above the start_text label (which breaks + * the ABS_ADDR calculation). See kernel/vmlinux.lds.S and tools/head_check.sh + * for more details. We would prefer to just keep a cacheline (0x80), but + * 0x100 seems to be how the linker aligns branch stub groups. + */ +#ifdef CONFIG_LD_HEAD_STUB_CATCH +#define OPEN_TEXT_SECTION(start) \ + .section ".linker_stub_catch","ax",@progbits; \ +linker_stub_catch: \ + . = 0x4; \ + text_start = (start) + 0x100; \ + .section ".text","ax",@progbits; \ + .balign 0x100; \ +start_text: +#else +#define OPEN_TEXT_SECTION(start) \ + text_start = (start); \ + .section ".text","ax",@progbits; \ + . = 0x0; \ +start_text: +#endif + +#define ZERO_FIXED_SECTION(sname, start, end) \ + sname##_start = (start); \ + sname##_end = (end); \ + sname##_len = (end) - (start); \ + define_data_ftsec sname; \ + . = 0x0; \ + . = sname##_len; + +#define USE_FIXED_SECTION(sname) \ + use_ftsec sname; + +#define USE_TEXT_SECTION() \ + .text + +#define CLOSE_FIXED_SECTION(sname) \ + USE_FIXED_SECTION(sname); \ + . = sname##_len; \ +end_##sname: + + +#define __FIXED_SECTION_ENTRY_BEGIN(sname, name, __align) \ + USE_FIXED_SECTION(sname); \ + .balign __align; \ + .global name; \ +name: + +#define FIXED_SECTION_ENTRY_BEGIN(sname, name) \ + __FIXED_SECTION_ENTRY_BEGIN(sname, name, IFETCH_ALIGN_BYTES) + +#define FIXED_SECTION_ENTRY_BEGIN_LOCATION(sname, name, start, size) \ + USE_FIXED_SECTION(sname); \ + name##_start = (start); \ + .if ((start) % (size) != 0); \ + .error "Fixed section exception vector misalignment"; \ + .endif; \ + .if ((size) != 0x20) && ((size) != 0x80) && ((size) != 0x100) && ((size) != 0x1000); \ + .error "Fixed section exception vector bad size"; \ + .endif; \ + .if (start) < sname##_start; \ + .error "Fixed section underflow"; \ + .abort; \ + .endif; \ + . = (start) - sname##_start; \ + .global name; \ +name: + +#define FIXED_SECTION_ENTRY_END_LOCATION(sname, name, start, size) \ + .if (start) + (size) > sname##_end; \ + .error "Fixed section overflow"; \ + .abort; \ + .endif; \ + .if (. - name > (start) + (size) - name##_start); \ + .error "Fixed entry overflow"; \ + .abort; \ + .endif; \ + . = ((start) + (size) - sname##_start); \ + + +/* + * These macros are used to change symbols in other fixed sections to be + * absolute or related to our current fixed section. + * + * - DEFINE_FIXED_SYMBOL / FIXED_SYMBOL_ABS_ADDR is used to find the + * absolute address of a symbol within a fixed section, from any section. + * + * - ABS_ADDR is used to find the absolute address of any symbol, from within + * a fixed section. + */ +// define label as being _in_ sname +#define DEFINE_FIXED_SYMBOL(label, sname) \ + label##_absolute = (label - start_ ## sname + sname ## _start) + +#define FIXED_SYMBOL_ABS_ADDR(label) \ + (label##_absolute) + +// find label from _within_ sname +#define ABS_ADDR(label, sname) (label - start_ ## sname + sname ## _start) + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_POWERPC_HEAD_64_H */ |