objtool: Add elf_create_reloc() helper

We have 4 instances of adding a relocation. Create a common helper
to avoid growing even more.

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/20210326151259.817438847@infradead.org

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 1d0415b..61fe29a 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -433,8 +433,7 @@ reachable:
 
 static int create_static_call_sections(struct objtool_file *file)
 {
-       struct section *sec, *reloc_sec;
-       struct reloc *reloc;
+       struct section *sec;
        struct static_call_site *site;
        struct instruction *insn;
        struct symbol *key_sym;
@@ -460,8 +459,7 @@ static int create_static_call_sections(struct objtool_file *file)
        if (!sec)
                return -1;
 
-       reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
-       if (!reloc_sec)
+       if (!elf_create_reloc_section(file->elf, sec, SHT_RELA))
                return -1;
 
        idx = 0;
@@ -471,25 +469,11 @@ static int create_static_call_sections(struct objtool_file *file)
                memset(site, 0, sizeof(struct static_call_site));
 
                /* populate reloc for 'addr' */
-               reloc = malloc(sizeof(*reloc));
-
-               if (!reloc) {
-                       perror("malloc");
-                       return -1;
-               }
-               memset(reloc, 0, sizeof(*reloc));
-
-               insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc);
-               if (!reloc->sym) {
-                       WARN_FUNC("static call tramp: missing containing symbol",
-                                 insn->sec, insn->offset);
+               if (elf_add_reloc_to_insn(file->elf, sec,
+                                         idx * sizeof(struct static_call_site),
+                                         R_X86_64_PC32,
+                                         insn->sec, insn->offset))
                        return -1;
-               }
-
-               reloc->type = R_X86_64_PC32;
-               reloc->offset = idx * sizeof(struct static_call_site);
-               reloc->sec = reloc_sec;
-               elf_add_reloc(file->elf, reloc);
 
                /* find key symbol */
                key_name = strdup(insn->call_dest->name);
@@ -526,18 +510,11 @@ static int create_static_call_sections(struct objtool_file *file)
                free(key_name);
 
                /* populate reloc for 'key' */
-               reloc = malloc(sizeof(*reloc));
-               if (!reloc) {
-                       perror("malloc");
+               if (elf_add_reloc(file->elf, sec,
+                                 idx * sizeof(struct static_call_site) + 4,
+                                 R_X86_64_PC32, key_sym,
+                                 is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
                        return -1;
-               }
-               memset(reloc, 0, sizeof(*reloc));
-               reloc->sym = key_sym;
-               reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0;
-               reloc->type = R_X86_64_PC32;
-               reloc->offset = idx * sizeof(struct static_call_site) + 4;
-               reloc->sec = reloc_sec;
-               elf_add_reloc(file->elf, reloc);
 
                idx++;
        }
@@ -547,8 +524,7 @@ static int create_static_call_sections(struct objtool_file *file)
 
 static int create_mcount_loc_sections(struct objtool_file *file)
 {
-       struct section *sec, *reloc_sec;
-       struct reloc *reloc;
+       struct section *sec;
        unsigned long *loc;
        struct instruction *insn;
        int idx;
@@ -571,8 +547,7 @@ static int create_mcount_loc_sections(struct objtool_file *file)
        if (!sec)
                return -1;
 
-       reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
-       if (!reloc_sec)
+       if (!elf_create_reloc_section(file->elf, sec, SHT_RELA))
                return -1;
 
        idx = 0;
@@ -581,32 +556,11 @@ static int create_mcount_loc_sections(struct objtool_file *file)
                loc = (unsigned long *)sec->data->d_buf + idx;
                memset(loc, 0, sizeof(unsigned long));
 
-               reloc = malloc(sizeof(*reloc));
-               if (!reloc) {
-                       perror("malloc");
+               if (elf_add_reloc_to_insn(file->elf, sec,
+                                         idx * sizeof(unsigned long),
+                                         R_X86_64_64,
+                                         insn->sec, insn->offset))
                        return -1;
-               }
-               memset(reloc, 0, sizeof(*reloc));
-
-               if (insn->sec->sym) {
-                       reloc->sym = insn->sec->sym;
-                       reloc->addend = insn->offset;
-               } else {
-                       reloc->sym = find_symbol_containing(insn->sec, insn->offset);
-
-                       if (!reloc->sym) {
-                               WARN("missing symbol for insn at offset 0x%lx\n",
-                                    insn->offset);
-                               return -1;
-                       }
-
-                       reloc->addend = insn->offset - reloc->sym->offset;
-               }
-
-               reloc->type = R_X86_64_64;
-               reloc->offset = idx * sizeof(unsigned long);
-               reloc->sec = reloc_sec;
-               elf_add_reloc(file->elf, reloc);
 
                idx++;
        }

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 374813e..0ab52ac 100644 (file)
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -211,32 +211,6 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
        return find_reloc_by_dest_range(elf, sec, offset, 1);
 }
 
-void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
-                             struct reloc *reloc)
-{
-       if (sec->sym) {
-               reloc->sym = sec->sym;
-               reloc->addend = offset;
-               return;
-       }
-
-       /*
-        * The Clang assembler strips section symbols, so we have to reference
-        * the function symbol instead:
-        */
-       reloc->sym = find_symbol_containing(sec, offset);
-       if (!reloc->sym) {
-               /*
-                * Hack alert.  This happens when we need to reference the NOP
-                * pad insn immediately after the function.
-                */
-               reloc->sym = find_symbol_containing(sec, offset - 1);
-       }
-
-       if (reloc->sym)
-               reloc->addend = offset - reloc->sym->offset;
-}
-
 static int read_sections(struct elf *elf)
 {
        Elf_Scn *s = NULL;
@@ -473,14 +447,66 @@ err:
        return -1;
 }
 
-void elf_add_reloc(struct elf *elf, struct reloc *reloc)
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+                 unsigned int type, struct symbol *sym, int addend)
 {
-       struct section *sec = reloc->sec;
+       struct reloc *reloc;
+
+       reloc = malloc(sizeof(*reloc));
+       if (!reloc) {
+               perror("malloc");
+               return -1;
+       }
+       memset(reloc, 0, sizeof(*reloc));
 
-       list_add_tail(&reloc->list, &sec->reloc_list);
+       reloc->sec = sec->reloc;
+       reloc->offset = offset;
+       reloc->type = type;
+       reloc->sym = sym;
+       reloc->addend = addend;
+
+       list_add_tail(&reloc->list, &sec->reloc->reloc_list);
        elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
 
-       sec->changed = true;
+       sec->reloc->changed = true;
+
+       return 0;
+}
+
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+                         unsigned long offset, unsigned int type,
+                         struct section *insn_sec, unsigned long insn_off)
+{
+       struct symbol *sym;
+       int addend;
+
+       if (insn_sec->sym) {
+               sym = insn_sec->sym;
+               addend = insn_off;
+
+       } else {
+               /*
+                * The Clang assembler strips section symbols, so we have to
+                * reference the function symbol instead:
+                */
+               sym = find_symbol_containing(insn_sec, insn_off);
+               if (!sym) {
+                       /*
+                        * Hack alert.  This happens when we need to reference
+                        * the NOP pad insn immediately after the function.
+                        */
+                       sym = find_symbol_containing(insn_sec, insn_off - 1);
+               }
+
+               if (!sym) {
+                       WARN("can't find symbol containing %s+0x%lx", insn_sec->name, insn_off);
+                       return -1;
+               }
+
+               addend = insn_off - sym->offset;
+       }
+
+       return elf_add_reloc(elf, sec, offset, type, sym, addend);
 }
 
 static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)

diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index fc576ed..825ad32 100644 (file)
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -123,7 +123,13 @@ static inline u32 reloc_hash(struct reloc *reloc)
 struct elf *elf_open_read(const char *name, int flags);
 struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
 struct section *elf_create_reloc_section(struct elf *elf, struct section *base, int reltype);
-void elf_add_reloc(struct elf *elf, struct reloc *reloc);
+
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+                 unsigned int type, struct symbol *sym, int addend);
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+                         unsigned long offset, unsigned int type,
+                         struct section *insn_sec, unsigned long insn_off);
+
 int elf_write_insn(struct elf *elf, struct section *sec,
                   unsigned long offset, unsigned int len,
                   const char *insn);
@@ -140,8 +146,6 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
                                     unsigned long offset, unsigned int len);
 struct symbol *find_func_containing(struct section *sec, unsigned long offset);
-void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
-                             struct reloc *reloc);
 
 #define for_each_sec(file, sec)                                                \
        list_for_each_entry(sec, &file->elf->sections, list)

diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index f534708..1b57be6 100644 (file)
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -82,12 +82,11 @@ static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi)
 }
 
 static int write_orc_entry(struct elf *elf, struct section *orc_sec,
-                          struct section *ip_rsec, unsigned int idx,
+                          struct section *ip_sec, unsigned int idx,
                           struct section *insn_sec, unsigned long insn_off,
                           struct orc_entry *o)
 {
        struct orc_entry *orc;
-       struct reloc *reloc;
 
        /* populate ORC data */
        orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
@@ -96,25 +95,9 @@ static int write_orc_entry(struct elf *elf, struct section *orc_sec,
        orc->bp_offset = bswap_if_needed(orc->bp_offset);
 
        /* populate reloc for ip */
-       reloc = malloc(sizeof(*reloc));
-       if (!reloc) {
-               perror("malloc");
+       if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
+                                 insn_sec, insn_off))
                return -1;
-       }
-       memset(reloc, 0, sizeof(*reloc));
-
-       insn_to_reloc_sym_addend(insn_sec, insn_off, reloc);
-       if (!reloc->sym) {
-               WARN("missing symbol for insn at offset 0x%lx",
-                    insn_off);
-               return -1;
-       }
-
-       reloc->type = R_X86_64_PC32;
-       reloc->offset = idx * sizeof(int);
-       reloc->sec = ip_rsec;
-
-       elf_add_reloc(elf, reloc);
 
        return 0;
 }
@@ -153,7 +136,7 @@ static unsigned long alt_group_len(struct alt_group *alt_group)
 
 int orc_create(struct objtool_file *file)
 {
-       struct section *sec, *ip_rsec, *orc_sec;
+       struct section *sec, *orc_sec;
        unsigned int nr = 0, idx = 0;
        struct orc_list_entry *entry;
        struct list_head orc_list;
@@ -242,13 +225,12 @@ int orc_create(struct objtool_file *file)
        sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
        if (!sec)
                return -1;
-       ip_rsec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
-       if (!ip_rsec)
+       if (!elf_create_reloc_section(file->elf, sec, SHT_RELA))
                return -1;
 
        /* Write ORC entries to sections: */
        list_for_each_entry(entry, &orc_list, list) {
-               if (write_orc_entry(file->elf, orc_sec, ip_rsec, idx++,
+               if (write_orc_entry(file->elf, orc_sec, sec, idx++,
                                    entry->insn_sec, entry->insn_off,
                                    &entry->orc))
                        return -1;