objtool: Keep track of retpoline call sites

commit 43d5430ad74ef5156353af7aec352426ec7a8e57 upstream.

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
[bwh: Backported to 5.10: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
index 82896d7615f5585e8b60c74c1417a2d62cf61336..8918de4f81898ef6939cfb5d5c7e7a0ee30fcbed 100644 (file)
--- a/tools/objtool/arch.h
+++ b/tools/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/check.c b/tools/objtool/check.c
index 2cb40985908129beb8216d143bdcf5324ca7387f..f87a8782c8173660075840828234cdffa39ff0ca 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));
@@ -786,13 +786,16 @@ 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;
@@ -854,7 +857,7 @@ 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);
                                }
                        }
@@ -938,6 +941,9 @@ 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;
 
@@ -945,7 +951,7 @@ 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);
                }
 
@@ -1655,6 +1661,11 @@ 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;
@@ -1683,6 +1694,10 @@ 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;
@@ -1719,6 +1734,15 @@ 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/check.h b/tools/objtool/check.h
index d255c43b134aba6793adbfdc36ba957059b64110..e0ae2fc13e67f12440328f7f9f3716616dda08b6 100644 (file)
--- a/tools/objtool/check.h
+++ b/tools/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 section *sec;
        unsigned long offset;
        unsigned int len;

diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index 9df0cd86d310d501035720a24837e3abc7581bfd..c0b1f5a99df9410a66df64abbdeafe961d734246 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);
        file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
        file.ignore_unreachables = no_unreachable;

diff --git a/tools/objtool/objtool.h b/tools/objtool/objtool.h
index 5e58d3537e2f2320715371a4f4b13bc388a36a92..0b57150ea0fe9df30dd5672a6d6b1bdf3b99d9bb 100644 (file)
--- a/tools/objtool/objtool.h
+++ b/tools/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;
        bool ignore_unreachables, c_file, hints, rodata;
 };