[RFC PATCH 16/17] objtool: arm64: Ignore replacement section for alternative callback
From: Julien Thierry <hidden>
Date: 2021-01-20 18:52:23
Also in:
linux-efi, linux-hardening, lkml
Subsystem:
objtool, the rest · Maintainers:
Josh Poimboeuf, Peter Zijlstra, Linus Torvalds
ARM64_CB_PATCH doesn't have static replacement instructions. Skip trying to validate the alternative section. Signed-off-by: Julien Thierry <redacted> --- tools/objtool/arch/arm64/special.c | 12 ++++++++++++ tools/objtool/check.c | 3 +++ 2 files changed, 15 insertions(+)
diff --git a/tools/objtool/arch/arm64/special.c b/tools/objtool/arch/arm64/special.c
index d47e5590ed60..aff8577e71e9 100644
--- a/tools/objtool/arch/arm64/special.c
+++ b/tools/objtool/arch/arm64/special.c@@ -24,6 +24,18 @@ struct switch_table_info { void arch_handle_alternative(unsigned short feature, struct special_alt *alt) { + if (alt->orig_len && !alt->new_len) { + /* + * ARM64_CB_PATCH has no alternative instruction. + * a callback is called at alternative replacement time + * to dynamically change the original instructions. + * + * ARM64_CB_PATCH is the last ARM64 feature, it's value changes + * every time a new feature is added. So the orig/alt region + * length are used to detect those alternatives + */ + alt->skip_alt = true; + } } bool arch_support_alt_relocation(struct special_alt *special_alt,
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index d902697a388e..8840af09f843 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c@@ -1182,6 +1182,9 @@ static int add_special_section_alts(struct objtool_file *file) continue; } + if (special_alt->skip_alt && !special_alt->new_len) + continue; + ret = handle_group_alt(file, special_alt, orig_insn, &new_insn); if (ret)
--
2.25.4
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