[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20180523195421.180248-18-thgarnie@google.com>
Date: Wed, 23 May 2018 12:54:11 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Herbert Xu <herbert@...dor.apana.org.au>,
"David S . Miller" <davem@...emloft.net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Thomas Garnier <thgarnie@...gle.com>,
Philippe Ombredanne <pombredanne@...b.com>,
Kate Stewart <kstewart@...uxfoundation.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Yonghong Song <yhs@...com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Kees Cook <keescook@...omium.org>,
Tom Lendacky <thomas.lendacky@....com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Dominik Brodowski <linux@...inikbrodowski.net>,
Borislav Petkov <bp@...en8.de>,
Borislav Petkov <bp@...e.de>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>,
Pavel Machek <pavel@....cz>,
Juergen Gross <jgross@...e.com>,
Alok Kataria <akataria@...are.com>,
Steven Rostedt <rostedt@...dmis.org>,
Jan Kiszka <jan.kiszka@...mens.com>,
Tejun Heo <tj@...nel.org>,
Christoph Lameter <cl@...ux.com>,
Dennis Zhou <dennisszhou@...il.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Alexey Dobriyan <adobriyan@...il.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Cao jin <caoj.fnst@...fujitsu.com>,
Francis Deslauriers <francis.deslauriers@...icios.com>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
Nicolas Pitre <nicolas.pitre@...aro.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Luis R . Rodriguez" <mcgrof@...nel.org>,
Arnd Bergmann <arnd@...db.de>,
Christopher Li <sparse@...isli.org>,
Jason Baron <jbaron@...mai.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Lukas Wunner <lukas@...ner.de>,
Dou Liyang <douly.fnst@...fujitsu.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
Petr Mladek <pmladek@...e.com>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Ingo Molnar <mingo@...nel.org>,
Nicholas Piggin <npiggin@...il.com>,
"H . J . Lu" <hjl.tools@...il.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Joerg Roedel <joro@...tes.org>,
David Woodhouse <dwmw@...zon.co.uk>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Rik van Riel <riel@...hat.com>,
Jia Zhang <qianyue.zj@...baba-inc.com>,
Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
Jonathan Corbet <corbet@....net>,
Jan Beulich <JBeulich@...e.com>,
Matthias Kaehlcke <mka@...omium.org>,
Baoquan He <bhe@...hat.com>,
Jan H . Schönherr <jschoenh@...zon.de>,
Daniel Micay <danielmicay@...il.com>
Cc: x86@...nel.org,
linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
xen-devel@...ts.xenproject.org,
linux-arch@...r.kernel.org,
linux-sparse@...r.kernel.org,
kvm@...r.kernel.org,
linux-doc@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH v3 17/27] x86/relocs: Handle PIE relocations
Change the relocation tool to correctly handle relocations generated by
-fPIE option:
- Add relocation for each entry of the .got section given the linker does not
generate R_X86_64_GLOB_DAT on a simple link.
- Ignore R_X86_64_GOTPCREL.
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
arch/x86/tools/relocs.c | 93 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 92 insertions(+), 1 deletion(-)
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 220e97841e49..a35cc337f883 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -32,6 +32,7 @@ struct section {
Elf_Sym *symtab;
Elf_Rel *reltab;
char *strtab;
+ Elf_Addr *got;
};
static struct section *secs;
@@ -293,6 +294,35 @@ static Elf_Sym *sym_lookup(const char *symname)
return 0;
}
+static Elf_Sym *sym_lookup_addr(Elf_Addr addr, const char **name)
+{
+ int i;
+ for (i = 0; i < ehdr.e_shnum; i++) {
+ struct section *sec = &secs[i];
+ long nsyms;
+ Elf_Sym *symtab;
+ Elf_Sym *sym;
+
+ if (sec->shdr.sh_type != SHT_SYMTAB)
+ continue;
+
+ nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
+ symtab = sec->symtab;
+
+ for (sym = symtab; --nsyms >= 0; sym++) {
+ if (sym->st_value == addr) {
+ if (name) {
+ *name = sym_name(sec->link->strtab,
+ sym);
+ }
+ return sym;
+ }
+ }
+ }
+ return 0;
+}
+
+
#if BYTE_ORDER == LITTLE_ENDIAN
#define le16_to_cpu(val) (val)
#define le32_to_cpu(val) (val)
@@ -513,6 +543,33 @@ static void read_relocs(FILE *fp)
}
}
+static void read_got(FILE *fp)
+{
+ int i;
+ for (i = 0; i < ehdr.e_shnum; i++) {
+ struct section *sec = &secs[i];
+ sec->got = NULL;
+ if (sec->shdr.sh_type != SHT_PROGBITS ||
+ strcmp(sec_name(i), ".got")) {
+ continue;
+ }
+ sec->got = malloc(sec->shdr.sh_size);
+ if (!sec->got) {
+ die("malloc of %d bytes for got failed\n",
+ sec->shdr.sh_size);
+ }
+ if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
+ die("Seek to %d failed: %s\n",
+ sec->shdr.sh_offset, strerror(errno));
+ }
+ if (fread(sec->got, 1, sec->shdr.sh_size, fp)
+ != sec->shdr.sh_size) {
+ die("Cannot read got: %s\n",
+ strerror(errno));
+ }
+ }
+}
+
static void print_absolute_symbols(void)
{
@@ -643,6 +700,32 @@ static void add_reloc(struct relocs *r, uint32_t offset)
r->offset[r->count++] = offset;
}
+/*
+ * The linker does not generate relocations for the GOT for the kernel.
+ * If a GOT is found, simulate the relocations that should have been included.
+ */
+static void walk_got_table(int (*process)(struct section *sec, Elf_Rel *rel,
+ Elf_Sym *sym, const char *symname),
+ struct section *sec)
+{
+ int i;
+ Elf_Addr entry;
+ Elf_Sym *sym;
+ const char *symname;
+ Elf_Rel rel;
+
+ for (i = 0; i < sec->shdr.sh_size/sizeof(Elf_Addr); i++) {
+ entry = sec->got[i];
+ sym = sym_lookup_addr(entry, &symname);
+ if (!sym)
+ die("Could not found got symbol for entry %d\n", i);
+ rel.r_offset = sec->shdr.sh_addr + i * sizeof(Elf_Addr);
+ rel.r_info = ELF_BITS == 64 ? R_X86_64_GLOB_DAT
+ : R_386_GLOB_DAT;
+ process(sec, &rel, sym, symname);
+ }
+}
+
static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
Elf_Sym *sym, const char *symname))
{
@@ -656,6 +739,8 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_REL_TYPE) {
+ if (sec->got)
+ walk_got_table(process, sec);
continue;
}
sec_symtab = sec->link;
@@ -765,6 +850,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
offset += per_cpu_load_addr;
switch (r_type) {
+ case R_X86_64_GOTPCREL:
case R_X86_64_NONE:
/* NONE can be ignored. */
break;
@@ -809,7 +895,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
* the relocations are processed.
* Make sure that the offset will fit.
*/
- if ((int32_t)offset != (int64_t)offset)
+ if (r_type != R_X86_64_64 && (int32_t)offset != (int64_t)offset)
die("Relocation offset doesn't fit in 32 bits\n");
if (r_type == R_X86_64_64)
@@ -818,6 +904,10 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
add_reloc(&relocs32, offset);
break;
+ case R_X86_64_GLOB_DAT:
+ add_reloc(&relocs64, offset);
+ break;
+
default:
die("Unsupported relocation type: %s (%d)\n",
rel_type(r_type), r_type);
@@ -1087,6 +1177,7 @@ void process(FILE *fp, int use_real_mode, int as_text,
read_strtabs(fp);
read_symtabs(fp);
read_relocs(fp);
+ read_got(fp);
if (ELF_BITS == 64)
percpu_init();
if (show_absolute_syms) {
--
2.17.0.441.gb46fe60e1d-goog
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
