objtool: Keep track of retpoline call sites

Provide infrastructure for architectures to rewrite/augment compiler
generated retpoline calls. Similar to what we do for static_call()s,
keep track of the instructions that are retpoline calls.

Use the same list_head, since a retpoline call cannot also be a
static_call.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 600fa67153d318e1d0446be04f471d52a8d4bba5..77074db1fcda834e4aebb96b0827d47165307c30 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -451,7 +451,7 @@ static int create_static_call_sections(struct objtool_file *file)
                return 0;
 
        idx = 0;
-       list_for_each_entry(insn, &file->static_call_list, static_call_node)
+       list_for_each_entry(insn, &file->static_call_list, call_node)
                idx++;
 
        sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
@@ -460,7 +460,7 @@ static int create_static_call_sections(struct objtool_file *file)
                return -1;
 
        idx = 0;
-       list_for_each_entry(insn, &file->static_call_list, static_call_node) {
+       list_for_each_entry(insn, &file->static_call_list, call_node) {
 
                site = (struct static_call_site *)sec->data->d_buf + idx;
                memset(site, 0, sizeof(struct static_call_site));
@@ -829,13 +829,16 @@ static int add_jump_destinations(struct objtool_file *file)
                        else
                                insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
 
+                       list_add_tail(&insn->call_node,
+                                     &file->retpoline_call_list);
+
                        insn->retpoline_safe = true;
                        continue;
                } else if (insn->func) {
                        /* internal or external sibling call (with reloc) */
                        insn->call_dest = reloc->sym;
                        if (insn->call_dest->static_call_tramp) {
-                               list_add_tail(&insn->static_call_node,
+                               list_add_tail(&insn->call_node,
                                              &file->static_call_list);
                        }
                        continue;
@@ -897,7 +900,7 @@ static int add_jump_destinations(struct objtool_file *file)
                                /* internal sibling call (without reloc) */
                                insn->call_dest = insn->jump_dest->func;
                                if (insn->call_dest->static_call_tramp) {
-                                       list_add_tail(&insn->static_call_node,
+                                       list_add_tail(&insn->call_node,
                                                      &file->static_call_list);
                                }
                        }
@@ -981,6 +984,9 @@ static int add_call_destinations(struct objtool_file *file)
                        insn->type = INSN_CALL_DYNAMIC;
                        insn->retpoline_safe = true;
 
+                       list_add_tail(&insn->call_node,
+                                     &file->retpoline_call_list);
+
                        remove_insn_ops(insn);
                        continue;
 
@@ -988,7 +994,7 @@ static int add_call_destinations(struct objtool_file *file)
                        insn->call_dest = reloc->sym;
 
                if (insn->call_dest && insn->call_dest->static_call_tramp) {
-                       list_add_tail(&insn->static_call_node,
+                       list_add_tail(&insn->call_node,
                                      &file->static_call_list);
                }
 
@@ -1714,6 +1720,11 @@ static void mark_rodata(struct objtool_file *file)
        file->rodata = found;
 }
 
+__weak int arch_rewrite_retpolines(struct objtool_file *file)
+{
+       return 0;
+}
+
 static int decode_sections(struct objtool_file *file)
 {
        int ret;
@@ -1742,6 +1753,10 @@ static int decode_sections(struct objtool_file *file)
        if (ret)
                return ret;
 
+       /*
+        * Must be before add_special_section_alts() as that depends on
+        * jump_dest being set.
+        */
        ret = add_jump_destinations(file);
        if (ret)
                return ret;
@@ -1778,6 +1793,15 @@ static int decode_sections(struct objtool_file *file)
        if (ret)
                return ret;
 
+       /*
+        * Must be after add_special_section_alts(), since this will emit
+        * alternatives. Must be after add_{jump,call}_destination(), since
+        * those create the call insn lists.
+        */
+       ret = arch_rewrite_retpolines(file);
+       if (ret)
+               return ret;
+
        return 0;
 }
 

diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index bb30993a1cedbd6d45d61096c26fa725591315e8..48b540a9d9e9678c5155ff7711d3e812c060ad90 100644 (file)
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -88,4 +88,6 @@ int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg);
 
 bool arch_is_retpoline(struct symbol *sym);
 
+int arch_rewrite_retpolines(struct objtool_file *file);
+
 #endif /* _ARCH_H */

diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index f5be798107bc9cae657ad867acf47095b0551099..e5528ce3961a8d67ef01f9b19228b14190a41b34 100644 (file)
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -39,7 +39,7 @@ struct alt_group {
 struct instruction {
        struct list_head list;
        struct hlist_node hash;
-       struct list_head static_call_node;
+       struct list_head call_node;
        struct list_head mcount_loc_node;
        struct section *sec;
        unsigned long offset;

diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index e68e37476c15df9880a202e9e84fdcf1403538da..e4084afb2304b1e60261e9c48e8a73225d5878cb 100644 (file)
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -18,6 +18,7 @@ struct objtool_file {
        struct elf *elf;
        struct list_head insn_list;
        DECLARE_HASHTABLE(insn_hash, 20);
+       struct list_head retpoline_call_list;
        struct list_head static_call_list;
        struct list_head mcount_loc_list;
        bool ignore_unreachables, c_file, hints, rodata;

diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index 7b97ce4994054c8125c5403755d10c5352a13a5f..3a3ea1b4e4da82a971f5754902469c835a69db69 100644 (file)
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -61,6 +61,7 @@ struct objtool_file *objtool_open_read(const char *_objname)
 
        INIT_LIST_HEAD(&file.insn_list);
        hash_init(file.insn_hash);
+       INIT_LIST_HEAD(&file.retpoline_call_list);
        INIT_LIST_HEAD(&file.static_call_list);
        INIT_LIST_HEAD(&file.mcount_loc_list);
        file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");