79ae44b66d
kpatch: update sympos for duplicate symbols in vmlinux create-diff-object: fix segment fault when sec2->rela is NULL Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
105 lines
3.6 KiB
Diff
105 lines
3.6 KiB
Diff
From 8f5c1ff32fcc519bf061f68a481116f622b9cef8 Mon Sep 17 00:00:00 2001
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From: Zhipeng Xie <xiezhipeng1@huawei.com>
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Date: Fri, 10 Sep 2021 04:34:40 -0400
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Subject: [PATCH] kpatch: update sympos for duplicate symbols in vmlinux
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kallsyms in vmlinux is sorted by address, so symbol order
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in vmlinux is different from /proc/kallsyms, update sympos
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when patching duplicate symbol function.
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Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
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Signed-off-by: hubin57 <hubin57@huawei.com>
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---
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kpatch-build/create-diff-object.c | 26 ++++++--------------------
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kpatch-build/lookup.c | 24 ++++++++++++++++++++++++
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kpatch-build/lookup.h | 2 ++
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3 files changed, 32 insertions(+), 20 deletions(-)
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diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c
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index afd5e3b..ff2b0e4 100644
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--- a/kpatch-build/create-diff-object.c
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+++ b/kpatch-build/create-diff-object.c
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@@ -2813,26 +2813,12 @@ static void kpatch_create_patches_sections(struct kpatch_elf *kelf,
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funcs[index].new_size = sym->sym.st_size;
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funcs[index].sympos = result.pos;
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if (lookup_is_duplicate_symbol(table, sym->name, objname, result.pos)) {
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- struct lookup_refsym refsym;
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- long offset;
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-
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- if (lookup_ref_symbol_offset(table, sym->name, &refsym,
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- objname, &offset))
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- ERROR("unresolvable ambiguity on symbol %s\n", sym->name);
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-
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- funcs[index].ref_offset = offset;
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-
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- /*
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- * Add a relocation that will populate
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- * the funcs[index].ref_name field.
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- */
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- ALLOC_LINK(rela, &relasec->relas);
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- rela->sym = strsym;
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- rela->type = absolute_rela_type;
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- rela->addend = offset_of_string(&kelf->strings, refsym.name);
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- rela->offset = (unsigned int)(index * sizeof(*funcs) +
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- offsetof(struct kpatch_patch_func, ref_name));
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-
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+ if (!strcmp(objname, "vmlinux")) {
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+ result.pos = get_vmlinux_duplicate_symbol_pos(table, sym->name, result.value);
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+ log_debug("update %s sympos from %ld to %ld\n",
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+ sym->name, funcs[index].sympos, result.pos);
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+ funcs[index].sympos = result.pos;
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+ }
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}
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diff --git a/kpatch-build/lookup.c b/kpatch-build/lookup.c
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index 888bcc9..aa8527d 100644
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--- a/kpatch-build/lookup.c
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+++ b/kpatch-build/lookup.c
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@@ -526,6 +526,30 @@ int lookup_global_symbol(struct lookup_table *table, char *name,
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return 1;
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}
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+/*
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+ * In case sometimes the sympos of duplicate symbols are different in vmlinux and
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+ * /proc/kallsyms, and causes lookup_local_symbol to save wrong sympos in result,
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+ * this function returns correct sympos of the symbol, by comparing
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+ * address value with the symbol in vmlinux symbol table.
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+ */
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+unsigned long get_vmlinux_duplicate_symbol_pos(struct lookup_table *table,
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+ char *name, unsigned long value)
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+{
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+ struct object_symbol *sym;
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+ unsigned long pos = 1;
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+ int i;
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+
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+ for_each_obj_symbol(i, sym, table) {
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+ if (strcmp(sym->name, name))
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+ continue;
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+
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+ if (sym->value < value)
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+ pos++;
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+ }
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+
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+ return pos;
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+}
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+
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int lookup_is_exported_symbol(struct lookup_table *table, char *name)
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{
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struct export_symbol *sym, *match = NULL;
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diff --git a/kpatch-build/lookup.h b/kpatch-build/lookup.h
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index daeea73..c745366 100644
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--- a/kpatch-build/lookup.h
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+++ b/kpatch-build/lookup.h
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@@ -37,5 +37,7 @@ int lookup_is_duplicate_symbol(struct lookup_table *table, char *name,
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int lookup_ref_symbol_offset(struct lookup_table *table, char *name,
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struct lookup_refsym *refsym, char *objname,
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long *offset);
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+unsigned long get_vmlinux_duplicate_symbol_pos(struct lookup_table *table, char *name,
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+ unsigned long value);
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#endif /* _LOOKUP_H_ */
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--
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2.27.0
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