[PATCH v4 31/63] objtool: Mark prefix functions

[Josh Poimboeuf]

In preparation for the objtool klp diff subcommand, introduce a flag to
identify __pfx_*() and __cfi_*() functions in advance so they don't need
to be manually identified every time a check is needed.

Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org>
---
 tools/objtool/check.c               | 5 +----
 tools/objtool/elf.c                 | 7 +++++++
 tools/objtool/include/objtool/elf.h | 6 ++++++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 57e3b0cde19f2..6f7ed34aea43e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3577,10 +3577,7 @@ static int validate_branch(struct objtool_file *file, 
struct symbol *func,
 
                if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
                        /* Ignore KCFI type preambles, which always fall 
through */
-                       if (!strncmp(func->name, "__cfi_", 6) ||
-                           !strncmp(func->name, "__pfx_", 6) ||
-                           !strncmp(func->name, "__pi___cfi_", 11) ||
-                           !strncmp(func->name, "__pi___pfx_", 11))
+                       if (is_prefix_func(func))
                                return 0;
 
                        if (file->ignore_unreachables)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 59568381486c9..775d017b1b79b 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -442,6 +442,13 @@ static void elf_add_symbol(struct elf *elf, struct symbol 
*sym)
        elf_hash_add(symbol, &sym->hash, sym->idx);
        elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
 
+       if (is_func_sym(sym) &&
+           (strstarts(sym->name, "__pfx_") ||
+            strstarts(sym->name, "__cfi_") ||
+            strstarts(sym->name, "__pi___pfx_") ||
+            strstarts(sym->name, "__pi___cfi_")))
+               sym->prefix = 1;
+
        if (is_func_sym(sym) && strstr(sym->name, ".cold"))
                sym->cold = 1;
        sym->pfunc = sym->cfunc = sym;
diff --git a/tools/objtool/include/objtool/elf.h 
b/tools/objtool/include/objtool/elf.h
index dbadcc88a3b26..79edf82e76ddf 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -73,6 +73,7 @@ struct symbol {
        u8 ignore            : 1;
        u8 nocfi             : 1;
        u8 cold              : 1;
+       u8 prefix            : 1;
        struct list_head pv_target;
        struct reloc *relocs;
        struct section *group_sec;
@@ -230,6 +231,11 @@ static inline bool is_local_sym(struct symbol *sym)
        return sym->bind == STB_LOCAL;
 }
 
+static inline bool is_prefix_func(struct symbol *sym)
+{
+       return sym->prefix;
+}
+
 static inline bool is_reloc_sec(struct section *sec)
 {
        return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
-- 
2.50.0