[PATCH v2 29/62] 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               | 3 +--
 tools/objtool/elf.c                 | 5 +++++
 tools/objtool/include/objtool/elf.h | 6 ++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a2a025ec57e8..6b2e57d9aaf8 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3601,8 +3601,7 @@ 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))
+                       if (is_prefix_func(func))
                                return 0;
 
                        if (file->ignore_unreachables)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 59568381486c..9a1fc0392b7f 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -442,6 +442,11 @@ 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) && sym->len == 16 &&
+           (strstarts(sym->name, "__pfx") || strstarts(sym->name, "__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 f41496b0ad8f..842faec1b9a9 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -72,6 +72,7 @@ struct symbol {
        u8 frame_pointer     : 1;
        u8 ignore            : 1;
        u8 cold              : 1;
+       u8 prefix            : 1;
        struct list_head pv_target;
        struct reloc *relocs;
        struct section *group_sec;
@@ -229,6 +230,11 @@ static inline bool is_local_sym(struct symbol *sym)
        return sym->bind == STB_LOCAL;
 }
 
+static inline bool is_prefix_func(struct symbol *sym)
+{
+       return is_func_sym(sym) && sym->prefix;
+}
+
 static inline bool is_reloc_sec(struct section *sec)
 {
        return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
-- 
2.49.0