Messages in this thread Patch in this message |  | | From | Jim Cromie <> | | Date | Sat, 02 May 2026 18:05:34 -0600 | | Subject | [PATCH 3/5] vmlinux.lds.h: Fix ALIGN(8) omission causing NULL ptr on i386 |
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Almost all uses of the BOUNDED_SECTION macros are ALIGN(8), either explicitly, or by being below an aligned section. The noteworthy exception is BOUNDED_SECTION(__dyndbg), which immediately follows BOUNDED_SECTION(__dyndbg_classes).
On i386, struct _ddebug_classmap is 28 bytes, so without an explicit ALIGN(8) in the macro, the following __dyndbg section gets misaligned, causing a NULL ptr deref in dynamic_debug_init().
So fix this with an explicit ALIGN(8) in the existing macros, and introduce _ALIGNED variants to handle the rare exceptions.
NOTES:
ORC_UNWIND_TABLE now uses _ALIGNED macros to match the explicit . = ALIGN(x) instructions, but keeps the instructions so the symbols between them are not "re-aligned"; scripts/sorttable.c does not tolerate sloppy padding.
Also add . = ALIGN(4) and change BOUNDED_SECTION to _ALIGNED, to agree with .orc_header, added here:
b9f174c811e3 ("x86/unwind/orc: Add ELF section with ORC version identifier")
Suggested-by: Louis Chauvet <louis.chauvet@bootlin.com> # _ALIGNED variants. Link: https://lore.kernel.org/lkml/177402491426.6181.12855763650074831089.b4-review@b4/ Signed-off-by: Jim Cromie <jim.cromie@gmail.com> --- include/asm-generic/bounded_sections.lds.h | 17 ++++++++++++++--- include/asm-generic/vmlinux.lds.h | 9 +++++---- 2 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/include/asm-generic/bounded_sections.lds.h b/include/asm-generic/bounded_sections.lds.h index 268cdc34389b..8ff3e3420f60 100644 --- a/include/asm-generic/bounded_sections.lds.h +++ b/include/asm-generic/bounded_sections.lds.h @@ -3,19 +3,30 @@ #ifndef _ASM_GENERIC_BOUNDED_SECTIONS_H #define _ASM_GENERIC_BOUNDED_SECTIONS_H -#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \ +#define BOUNDED_SECTION_PRE_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, _ALIGNED_) \ + . = ALIGN(_ALIGNED_); \ _BEGIN_##_label_ = .; \ KEEP(*(_sec_)) \ _END_##_label_ = .; -#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \ +#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \ + BOUNDED_SECTION_PRE_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, 8) + +#define BOUNDED_SECTION_POST_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, _ALIGNED_) \ + . = ALIGN(_ALIGNED_); \ _label_##_BEGIN_ = .; \ KEEP(*(_sec_)) \ _label_##_END_ = .; +#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \ + BOUNDED_SECTION_POST_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, 8) + #define BOUNDED_SECTION_BY(_sec_, _label_) \ BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop) -#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec) +#define BOUNDED_SECTION_BY_ALIGNED(_sec_, _label_, _ALIGNED_) \ + BOUNDED_SECTION_PRE_LABEL_ALIGNED(_sec_, _label_, __start, __stop, _ALIGNED_) + +#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec) #endif /* _ASM_GENERIC_BOUNDED_SECTIONS_H */ diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index f78300aea8f6..d3f20b411e16 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -641,7 +641,7 @@ #define EXCEPTION_TABLE(align) \ . = ALIGN(align); \ __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { \ - BOUNDED_SECTION_BY(__ex_table, ___ex_table) \ + BOUNDED_SECTION_BY_ALIGNED(__ex_table, ___ex_table, align) \ } /* @@ -833,16 +833,17 @@ #ifdef CONFIG_UNWINDER_ORC #define ORC_UNWIND_TABLE \ + . = ALIGN(4); \ .orc_header : AT(ADDR(.orc_header) - LOAD_OFFSET) { \ - BOUNDED_SECTION_BY(.orc_header, _orc_header) \ + BOUNDED_SECTION_BY_ALIGNED(.orc_header, _orc_header, 4) \ } \ . = ALIGN(4); \ .orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \ - BOUNDED_SECTION_BY(.orc_unwind_ip, _orc_unwind_ip) \ + BOUNDED_SECTION_BY_ALIGNED(.orc_unwind_ip, _orc_unwind_ip, 4)\ } \ . = ALIGN(2); \ .orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \ - BOUNDED_SECTION_BY(.orc_unwind, _orc_unwind) \ + BOUNDED_SECTION_BY_ALIGNED(.orc_unwind, _orc_unwind, 2) \ } \ text_size = _etext - _stext; \ . = ALIGN(4); \ -- 2.54.0
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