113 lines
3.8 KiB
Diff
113 lines
3.8 KiB
Diff
From a81f64c1eae14f2b0da8168ca60b3d9beb0a9fb0 Mon Sep 17 00:00:00 2001
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From: Zhipeng Xie <xiezhipeng1@huawei.com>
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Date: Wed, 30 Dec 2020 21:13:10 -0500
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Subject: [PATCH 20/24] support remove static variables using
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KPATCH_IGNORE_STATIC
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Static variables will be removed due to compiler optimization.
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And some static variables can be treated as new variables, such as
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static variables in print limit macros. So add KPATCH_IGNORE_STATIC
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to tell kpatch to treat the static variables as new variables.
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Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
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---
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kmod/patch/kpatch-macros.h | 4 +++
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kpatch-build/create-diff-object.c | 45 ++++++++++++++++++++++++++++++-
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2 files changed, 48 insertions(+), 1 deletion(-)
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diff --git a/kmod/patch/kpatch-macros.h b/kmod/patch/kpatch-macros.h
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index caaadbc..ee455d2 100644
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--- a/kmod/patch/kpatch-macros.h
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+++ b/kmod/patch/kpatch-macros.h
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@@ -12,6 +12,10 @@
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# define __kpatch_section(section) __section(#section)
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#endif
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+#define KPATCH_IGNORE_STATIC(_static) \
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+ char *__UNIQUE_ID(kpatch_ignore_static_) __section(.kpatch.ignore.statics) = _static;
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+
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+
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/*
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* KPATCH_IGNORE_SECTION macro
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*
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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 0bef022..f83000b 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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@@ -1345,6 +1345,40 @@ static struct rela *kpatch_find_static_twin_ref(struct section *rela_sec, struct
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return NULL;
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}
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+static int kpatch_mark_ignored_statics(struct kpatch_elf *kelf, struct symbol *sym)
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+{
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+ struct section *sec, *strsec;
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+ struct rela *rela;
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+ char *name;
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+
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+ sec = find_section_by_name(&kelf->sections, ".kpatch.ignore.statics");
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+ if (!sec)
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+ return 0;
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+
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+ list_for_each_entry(rela, &sec->rela->relas, list) {
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+ strsec = rela->sym->sec;
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+ strsec->status = CHANGED;
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+ /*
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+ * Include the string section here. This is because the
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+ * KPATCH_IGNORE_STATIC() macro is passed a literal string
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+ * by the patch author, resulting in a change to the string
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+ * section. If we don't include it, then we will potentially
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+ * get a "changed section not included" error in
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+ * kpatch_verify_patchability() if no other function based change
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+ * also changes the string section. We could try to exclude each
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+ * literal string added to the section by KPATCH_IGNORE_STATIC()
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+ * from the section data comparison, but this is a simpler way.
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+ */
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+ strsec->include = 1;
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+ strsec->secsym->include = 1;
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+ name = strsec->data->d_buf + rela->addend;
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+ if (!strncmp(name, sym->name, strlen(name)))
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+ return 1;
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+ }
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+
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+ return 0;
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+}
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+
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/*
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* gcc renames static local variables by appending a period and a number. For
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* example, __foo could be renamed to __foo.31452. Unfortunately this number
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@@ -1425,6 +1459,11 @@ static void kpatch_correlate_static_local_variables(struct kpatch_elf *orig,
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if (sym->twin)
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continue;
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+ if (kpatch_mark_ignored_statics(patched, sym)) {
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+ log_normal("KPATCH_IGNORE_STATIC:ignore static variable %s\n", sym->name);
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+ continue;
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+ }
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+
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bundled = sym == sym->sec->sym;
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if (bundled && sym->sec == sec->base) {
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/*
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@@ -1482,6 +1521,11 @@ static void kpatch_correlate_static_local_variables(struct kpatch_elf *orig,
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if (!kpatch_is_normal_static_local(sym))
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continue;
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+ if (kpatch_mark_ignored_statics(patched, sym)) {
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+ log_normal("KPATCH_IGNORE_STATIC:ignore static variable %s\n", sym->name);
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+ continue;
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+ }
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+
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if (!sec->twin && sec->base->sym) {
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struct symbol *parent = NULL;
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@@ -1525,7 +1569,6 @@ static void kpatch_correlate_static_local_variables(struct kpatch_elf *orig,
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log_normal("WARNING: unable to correlate static local variable %s used by %s, assuming variable is new\n",
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sym->name,
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kpatch_section_function_name(sec));
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- return;
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}
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}
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}
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--
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2.23.0
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