From 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sat, 27 Apr 2024 12:05:51 +0200
Subject: Adding upstream version 5.10.209.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 tools/objtool/special.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)
 create mode 100644 tools/objtool/special.c

(limited to 'tools/objtool/special.c')

diff --git a/tools/objtool/special.c b/tools/objtool/special.c
new file mode 100644
index 000000000..aff0cee7b
--- /dev/null
+++ b/tools/objtool/special.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+/*
+ * This file reads all the special sections which have alternate instructions
+ * which can be patched in or redirected to at runtime.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "builtin.h"
+#include "special.h"
+#include "warn.h"
+#include "arch_special.h"
+
+struct special_entry {
+	const char *sec;
+	bool group, jump_or_nop;
+	unsigned char size, orig, new;
+	unsigned char orig_len, new_len; /* group only */
+	unsigned char feature; /* ALTERNATIVE macro CPU feature */
+};
+
+struct special_entry entries[] = {
+	{
+		.sec = ".altinstructions",
+		.group = true,
+		.size = ALT_ENTRY_SIZE,
+		.orig = ALT_ORIG_OFFSET,
+		.orig_len = ALT_ORIG_LEN_OFFSET,
+		.new = ALT_NEW_OFFSET,
+		.new_len = ALT_NEW_LEN_OFFSET,
+		.feature = ALT_FEATURE_OFFSET,
+	},
+	{
+		.sec = "__jump_table",
+		.jump_or_nop = true,
+		.size = JUMP_ENTRY_SIZE,
+		.orig = JUMP_ORIG_OFFSET,
+		.new = JUMP_NEW_OFFSET,
+	},
+	{
+		.sec = "__ex_table",
+		.size = EX_ENTRY_SIZE,
+		.orig = EX_ORIG_OFFSET,
+		.new = EX_NEW_OFFSET,
+	},
+	{},
+};
+
+void __weak arch_handle_alternative(unsigned short feature, struct special_alt *alt)
+{
+}
+
+static void reloc_to_sec_off(struct reloc *reloc, struct section **sec,
+			     unsigned long *off)
+{
+	*sec = reloc->sym->sec;
+	*off = reloc->sym->offset + reloc->addend;
+}
+
+static int get_alt_entry(struct elf *elf, struct special_entry *entry,
+			 struct section *sec, int idx,
+			 struct special_alt *alt)
+{
+	struct reloc *orig_reloc, *new_reloc;
+	unsigned long offset;
+
+	offset = idx * entry->size;
+
+	alt->group = entry->group;
+	alt->jump_or_nop = entry->jump_or_nop;
+
+	if (alt->group) {
+		alt->orig_len = *(unsigned char *)(sec->data->d_buf + offset +
+						   entry->orig_len);
+		alt->new_len = *(unsigned char *)(sec->data->d_buf + offset +
+						  entry->new_len);
+	}
+
+	if (entry->feature) {
+		unsigned short feature;
+
+		feature = *(unsigned short *)(sec->data->d_buf + offset +
+					      entry->feature);
+		arch_handle_alternative(feature, alt);
+	}
+
+	orig_reloc = find_reloc_by_dest(elf, sec, offset + entry->orig);
+	if (!orig_reloc) {
+		WARN_FUNC("can't find orig reloc", sec, offset + entry->orig);
+		return -1;
+	}
+
+	reloc_to_sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off);
+
+	if (!entry->group || alt->new_len) {
+		new_reloc = find_reloc_by_dest(elf, sec, offset + entry->new);
+		if (!new_reloc) {
+			WARN_FUNC("can't find new reloc",
+				  sec, offset + entry->new);
+			return -1;
+		}
+
+		reloc_to_sec_off(new_reloc, &alt->new_sec, &alt->new_off);
+
+		/* _ASM_EXTABLE_EX hack */
+		if (alt->new_off >= 0x7ffffff0)
+			alt->new_off -= 0x7ffffff0;
+	}
+
+	return 0;
+}
+
+/*
+ * Read all the special sections and create a list of special_alt structs which
+ * describe all the alternate instructions which can be patched in or
+ * redirected to at runtime.
+ */
+int special_get_alts(struct elf *elf, struct list_head *alts)
+{
+	struct special_entry *entry;
+	struct section *sec;
+	unsigned int nr_entries;
+	struct special_alt *alt;
+	int idx, ret;
+
+	INIT_LIST_HEAD(alts);
+
+	for (entry = entries; entry->sec; entry++) {
+		sec = find_section_by_name(elf, entry->sec);
+		if (!sec)
+			continue;
+
+		if (sec->len % entry->size != 0) {
+			WARN("%s size not a multiple of %d",
+			     sec->name, entry->size);
+			return -1;
+		}
+
+		nr_entries = sec->len / entry->size;
+
+		for (idx = 0; idx < nr_entries; idx++) {
+			alt = malloc(sizeof(*alt));
+			if (!alt) {
+				WARN("malloc failed");
+				return -1;
+			}
+			memset(alt, 0, sizeof(*alt));
+
+			ret = get_alt_entry(elf, entry, sec, idx, alt);
+			if (ret > 0)
+				continue;
+			if (ret < 0)
+				return ret;
+
+			list_add_tail(&alt->list, alts);
+		}
+	}
+
+	return 0;
+}
-- 
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