[PATCH v3 18/21] objtool: Allow multiple pv_ops arrays

[Juergen Gross <jgross@suse.com>]

Having a single large pv_ops array has the main disadvantage of needing
all prototypes of the single array members in one header file. This is
adding up to the need to include lots of otherwise unrelated headers.

In order to allow multiple smaller pv_ops arrays dedicated to one
area of the kernel each, allow multiple arrays in objtool.

For better performance limit the possible names of the arrays to
start with "pv_ops".

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- new patch
---
 tools/objtool/arch/x86/decode.c       |  8 ++-
 tools/objtool/check.c                 | 74 +++++++++++++++++++++------
 tools/objtool/include/objtool/check.h |  2 +
 3 files changed, 66 insertions(+), 18 deletions(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 0ad5cc70ecbe..d253148edc6a 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -649,10 +649,14 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 			immr = find_reloc_by_dest(elf, (void *)sec, offset+3);
 			disp = find_reloc_by_dest(elf, (void *)sec, offset+7);
 
-			if (!immr || strcmp(immr->sym->name, "pv_ops"))
+			if (!immr || strncmp(immr->sym->name, "pv_ops", 6))
 				break;
 
-			idx = (reloc_addend(immr) + 8) / sizeof(void *);
+			idx = pv_ops_idx_off(immr->sym->name);
+			if (idx < 0)
+				break;
+
+			idx += (reloc_addend(immr) + 8) / sizeof(void *);
 
 			func = disp->sym;
 			if (disp->sym->type == STT_SECTION)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8793b73d50d2..1675c16c3793 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -542,21 +542,57 @@ static int decode_instructions(struct objtool_file *file)
 }
 
 /*
- * Read the pv_ops[] .data table to find the static initialized values.
+ * Known pv_ops*[] arrays.
  */
-static int add_pv_ops(struct objtool_file *file, const char *symname)
+static struct {
+	const char *name;
+	int idx_off;
+} pv_ops_tables[] = {
+	{ .name = "pv_ops", },
+	{ .name = NULL, .idx_off = -1 }
+};
+
+/*
+ * Get index offset for a pv_ops* array.
+ */
+int pv_ops_idx_off(const char *symname)
+{
+	int idx;
+
+	for (idx = 0; pv_ops_tables[idx].name; idx++) {
+		if (!strcmp(symname, pv_ops_tables[idx].name))
+			break;
+	}
+
+	return pv_ops_tables[idx].idx_off;
+}
+
+/*
+ * Read a pv_ops*[] .data table to find the static initialized values.
+ */
+static int add_pv_ops(struct objtool_file *file, int pv_ops_idx)
 {
 	struct symbol *sym, *func;
 	unsigned long off, end;
 	struct reloc *reloc;
-	int idx;
+	int idx, idx_off;
+	const char *symname;
 
+	symname = pv_ops_tables[pv_ops_idx].name;
 	sym = find_symbol_by_name(file->elf, symname);
-	if (!sym)
-		return 0;
+	if (!sym) {
+		ERROR("Unknown pv_ops array %s", symname);
+		return -1;
+	}
 
 	off = sym->offset;
 	end = off + sym->len;
+	idx_off = pv_ops_tables[pv_ops_idx].idx_off;
+	if (idx_off < 0) {
+		ERROR("pv_ops array %s has unknown index offset", symname);
+		return -1;
+	}
+
 	for (;;) {
 		reloc = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
 		if (!reloc)
@@ -574,7 +610,7 @@ static int add_pv_ops(struct objtool_file *file, const char *symname)
 			return -1;
 		}
 
-		if (objtool_pv_add(file, idx, func))
+		if (objtool_pv_add(file, idx + idx_off, func))
 			return -1;
 
 		off = reloc_offset(reloc) + 1;
@@ -590,11 +626,6 @@ static int add_pv_ops(struct objtool_file *file, const char *symname)
  */
 static int init_pv_ops(struct objtool_file *file)
 {
-	static const char *pv_ops_tables[] = {
-		"pv_ops",
-		NULL,
-	};
-	const char *pv_ops;
 	struct symbol *sym;
 	int idx, nr, ret;
 
@@ -603,11 +634,20 @@ static int init_pv_ops(struct objtool_file *file)
 
 	file->pv_ops = NULL;
 
-	sym = find_symbol_by_name(file->elf, "pv_ops");
-	if (!sym)
+	nr = 0;
+	for (idx = 0; pv_ops_tables[idx].name; idx++) {
+		sym = find_symbol_by_name(file->elf, pv_ops_tables[idx].name);
+		if (!sym) {
+			pv_ops_tables[idx].idx_off = -1;
+			continue;
+		}
+		pv_ops_tables[idx].idx_off = nr;
+		nr += sym->len / sizeof(unsigned long);
+	}
+
+	if (nr == 0)
 		return 0;
 
-	nr = sym->len / sizeof(unsigned long);
 	file->pv_ops = calloc(sizeof(struct pv_state), nr);
 	if (!file->pv_ops) {
 		ERROR_GLIBC("calloc");
@@ -617,8 +657,10 @@ static int init_pv_ops(struct objtool_file *file)
 	for (idx = 0; idx < nr; idx++)
 		INIT_LIST_HEAD(&file->pv_ops[idx].targets);
 
-	for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++) {
-		ret = add_pv_ops(file, pv_ops);
+	for (idx = 0; pv_ops_tables[idx].name; idx++) {
+		if (pv_ops_tables[idx].idx_off < 0)
+			continue;
+		ret = add_pv_ops(file, idx);
 		if (ret)
 			return ret;
 	}
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 00fb745e7233..51f2396c5943 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -125,4 +125,6 @@ struct instruction *next_insn_same_sec(struct objtool_file *file, struct instruc
 	     insn && insn->sec == _sec;					\
 	     insn = next_insn_same_sec(file, insn))
 
+int pv_ops_idx_off(const char *symname);
+
 #endif /* _CHECK_H */
-- 
2.51.0