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bug/x86/arm: Align bug_frames sections.
Most of the WARN_ON or BUG_ON sections are properly aligned on x86. However on ARM and on x86 assembler the macros don't include any alignment information - hence they end up being the default byte granularity. On ARM32 it is paramount that the alignment is word-size (4) otherwise if one tries to use (uint32_t*) access (such as livepatch ELF relocations) we get a Data Abort. Enforcing bug_frames to have the proper alignment across all architectures and in both C and x86 makes them all the same. Furthermore on x86 the bloat-o-meter detects that with this change: add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0) function old new delta On ARM32: add/remove: 1/0 grow/shrink: 0/1 up/down: 384/-288 (96) function old new delta gnttab_unpopulate_status_frames - 384 +384 do_grant_table_op 10808 10520 -288 And ARM64: add/remove: 1/2 grow/shrink: 0/1 up/down: 4164/-4236 (-72) function old new delta gnttab_map_grant_ref - 4164 +4164 do_grant_table_op 9892 9836 -56 grant_map_exists 300 - -300 __gnttab_map_grant_ref 3880 - -3880 Reviewed-by: Julien Grall <julien.grall@arm.com> Acked-by: Jan Beulich <jbeulich@suse.com> [x86 parts] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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@@ -79,7 +79,6 @@ SECTIONS
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.rodata : {
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.rodata : {
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_srodata = .;
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_srodata = .;
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/* Bug frames table */
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/* Bug frames table */
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. = ALIGN(4);
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__start_bug_frames = .;
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__start_bug_frames = .;
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*(.bug_frames.0)
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*(.bug_frames.0)
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__stop_bug_frames_0 = .;
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__stop_bug_frames_0 = .;
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@@ -52,6 +52,7 @@ struct bug_frame {
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".popsection\n" \
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".popsection\n" \
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".pushsection .bug_frames." __stringify(type) ", \"a\", %progbits\n"\
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".pushsection .bug_frames." __stringify(type) ", \"a\", %progbits\n"\
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"4:\n" \
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"4:\n" \
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".p2align 2\n" \
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".long (1b - 4b)\n" \
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".long (1b - 4b)\n" \
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".long (2b - 4b)\n" \
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".long (2b - 4b)\n" \
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".long (3b - 4b)\n" \
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".long (3b - 4b)\n" \
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@@ -98,6 +98,7 @@ extern const struct bug_frame __start_bug_frames[],
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.popsection
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.popsection
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.pushsection .bug_frames.\type, "a", @progbits
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.pushsection .bug_frames.\type, "a", @progbits
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.p2align 2
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.L\@bf:
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.L\@bf:
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.long (.L\@ud - .L\@bf) + \
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.long (.L\@ud - .L\@bf) + \
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((\line >> BUG_LINE_LO_WIDTH) << BUG_DISP_WIDTH)
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((\line >> BUG_LINE_LO_WIDTH) << BUG_DISP_WIDTH)
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