Merge branch 'objtool/urgent' into objtool/core

 Conflicts:
	tools/objtool/elf.c
	tools/objtool/elf.h
	tools/objtool/orc_gen.c
	tools/objtool/check.c

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>

Author: Peter Zijlstra

arch/x86/Kconfig

@@ -67,7 +67,7 @@ config X86
 	select ARCH_HAS_FILTER_PGPROT
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_KCOV			if X86_64
+	select ARCH_HAS_KCOV			if X86_64 && STACK_VALIDATION
 	select ARCH_HAS_MEM_ENCRYPT
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE

tools/objtool/arch.h

@@ -84,4 +84,6 @@ unsigned long arch_jump_destination(struct instruction *insn);
 
 unsigned long arch_dest_reloc_offset(int addend);
 
+const char *arch_nop_insn(int len);
+
 #endif /* _ARCH_H */

tools/objtool/arch/x86/decode.c

@@ -565,3 +565,21 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state)
 	state->regs[16].base = CFI_CFA;
 	state->regs[16].offset = -8;
 }
+
+const char *arch_nop_insn(int len)
+{
+	static const char nops[5][5] = {
+		/* 1 */ { 0x90 },
+		/* 2 */ { 0x66, 0x90 },
+		/* 3 */ { 0x0f, 0x1f, 0x00 },
+		/* 4 */ { 0x0f, 0x1f, 0x40, 0x00 },
+		/* 5 */ { 0x0f, 0x1f, 0x44, 0x00, 0x00 },
+	};
+
+	if (len < 1 || len > 5) {
+		WARN("invalid NOP size: %d\n", len);
+		return NULL;
+	}
+
+	return nops[len-1];
+}

tools/objtool/arch/x86/include/arch_elf.h

@@ -0,0 +1,6 @@
+#ifndef _OBJTOOL_ARCH_ELF
+#define _OBJTOOL_ARCH_ELF
+
+#define R_NONE R_X86_64_NONE
+
+#endif /* _OBJTOOL_ARCH_ELF */

tools/objtool/check.c

@@ -12,6 +12,7 @@
 #include "check.h"
 #include "special.h"
 #include "warn.h"
+#include "arch_elf.h"
 
 #include <linux/hashtable.h>
 #include <linux/kernel.h>
@@ -765,6 +766,24 @@ static int add_call_destinations(struct objtool_file *file)
 		} else
 			insn->call_dest = reloc->sym;
 
+		/*
+		 * Many compilers cannot disable KCOV with a function attribute
+		 * so they need a little help, NOP out any KCOV calls from noinstr
+		 * text.
+		 */
+		if (insn->sec->noinstr &&
+		    !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
+			if (reloc) {
+				reloc->type = R_NONE;
+				elf_write_reloc(file->elf, reloc);
+			}
+
+			elf_write_insn(file->elf, insn->sec,
+				       insn->offset, insn->len,
+				       arch_nop_insn(insn->len));
+			insn->type = INSN_NOP;
+		}
+
 		/*
 		 * Whatever stack impact regular CALLs have, should be undone
 		 * by the RETURN of the called function.
@@ -2740,7 +2759,7 @@ int check(const char *_objname, bool orc)
 
 	objname = _objname;
 
-	file.elf = elf_open_read(objname, orc ? O_RDWR : O_RDONLY);
+	file.elf = elf_open_read(objname, O_RDWR);
 	if (!file.elf)
 		return 1;
 
@@ -2801,7 +2820,9 @@ int check(const char *_objname, bool orc)
 		ret = create_orc_sections(&file);
 		if (ret < 0)
 			goto out;
+	}
 
+	if (file.elf->changed) {
 		ret = elf_write(file.elf);
 		if (ret < 0)
 			goto out;

tools/objtool/elf.c

@@ -563,8 +563,10 @@ static int read_relocs(struct elf *elf)
 				break;
 			default: return -1;
 			}
-			reloc->sym = find_symbol_by_index(elf, symndx);
+
 			reloc->sec = sec;
+			reloc->idx = i;
+			reloc->sym = find_symbol_by_index(elf, symndx);
 			if (!reloc->sym) {
 				WARN("can't find reloc entry symbol %d for %s",
 				     symndx, sec->name);
@@ -747,6 +749,8 @@ struct section *elf_create_section(struct elf *elf, const char *name,
 	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
 	elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 
+	elf->changed = true;
+
 	return sec;
 }
 
@@ -880,11 +884,14 @@ static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
 	return 0;
 }
 
-int elf_rebuild_reloc_section(struct section *sec)
+int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
 {
 	struct reloc *reloc;
 	int nr;
 
+	sec->changed = true;
+	elf->changed = true;
+
 	nr = 0;
 	list_for_each_entry(reloc, &sec->reloc_list, list)
 		nr++;
@@ -896,7 +903,54 @@ int elf_rebuild_reloc_section(struct section *sec)
 	}
 }
 
-int elf_write(const struct elf *elf)
+int elf_write_insn(struct elf *elf, struct section *sec,
+		   unsigned long offset, unsigned int len,
+		   const char *insn)
+{
+	Elf_Data *data = sec->data;
+
+	if (data->d_type != ELF_T_BYTE || data->d_off) {
+		WARN("write to unexpected data for section: %s", sec->name);
+		return -1;
+	}
+
+	memcpy(data->d_buf + offset, insn, len);
+	elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
+
+	elf->changed = true;
+
+	return 0;
+}
+
+int elf_write_reloc(struct elf *elf, struct reloc *reloc)
+{
+	struct section *sec = reloc->sec;
+
+	if (sec->sh.sh_type == SHT_REL) {
+		reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		reloc->rel.r_offset = reloc->offset;
+
+		if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
+			WARN_ELF("gelf_update_rel");
+			return -1;
+		}
+	} else {
+		reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		reloc->rela.r_addend = reloc->addend;
+		reloc->rela.r_offset = reloc->offset;
+
+		if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
+			WARN_ELF("gelf_update_rela");
+			return -1;
+		}
+	}
+
+	elf->changed = true;
+
+	return 0;
+}
+
+int elf_write(struct elf *elf)
 {
 	struct section *sec;
 	Elf_Scn *s;
@@ -913,6 +967,8 @@ int elf_write(const struct elf *elf)
 				WARN_ELF("gelf_update_shdr");
 				return -1;
 			}
+
+			sec->changed = false;
 		}
 	}
 
@@ -925,6 +981,8 @@ int elf_write(const struct elf *elf)
 		return -1;
 	}
 
+	elf->changed = false;
+
 	return 0;
 }
 

tools/objtool/elf.h

@@ -67,9 +67,10 @@ struct reloc {
 	};
 	struct section *sec;
 	struct symbol *sym;
-	unsigned int type;
 	unsigned long offset;
+	unsigned int type;
 	int addend;
+	int idx;
 	bool jump_table_start;
 };
 
@@ -79,6 +80,7 @@ struct elf {
 	Elf *elf;
 	GElf_Ehdr ehdr;
 	int fd;
+	bool changed;
 	char *name;
 	struct list_head sections;
 	DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
@@ -121,7 +123,11 @@ struct elf *elf_open_read(const char *name, int flags);
 struct section *elf_create_section(struct elf *elf, const char *name, 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_write(const struct elf *elf);
+int elf_write_insn(struct elf *elf, struct section *sec,
+		   unsigned long offset, unsigned int len,
+		   const char *insn);
+int elf_write_reloc(struct elf *elf, struct reloc *reloc);
+int elf_write(struct elf *elf);
 void elf_close(struct elf *elf);
 
 struct section *find_section_by_name(const struct elf *elf, const char *name);
@@ -133,7 +139,7 @@ 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);
-int elf_rebuild_reloc_section(struct section *sec);
+int elf_rebuild_reloc_section(struct elf *elf, struct section *sec);
 
 #define for_each_sec(file, sec)						\
 	list_for_each_entry(sec, &file->elf->sections, list)

tools/objtool/orc_gen.c

@@ -222,7 +222,7 @@ int create_orc_sections(struct objtool_file *file)
 		}
 	}
 
-	if (elf_rebuild_reloc_section(ip_relocsec))
+	if (elf_rebuild_reloc_section(file->elf, ip_relocsec))
 		return -1;
 
 	return 0;