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authorH. Peter Anvin <hpa@zytor.com>2009-05-25 10:33:12 -0700
committerH. Peter Anvin <hpa@zytor.com>2009-05-25 10:33:12 -0700
commit4a211f679cd19207085b2e53c1c6572a47226fc1 (patch)
tree05be60a3fa9f1f86b753834910e5cb16599733f0 /com32/tools
parent14952a63ac017687efacf5d1f02de2b35e7e45f7 (diff)
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com32r: allow absolute and relative symbols based on regex
Allow relocs.c to sort linker-assigned absolute symbols into true absolute and relative symbols based on regular expressions. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'com32/tools')
-rw-r--r--com32/tools/relocs.c110
1 files changed, 73 insertions, 37 deletions
diff --git a/com32/tools/relocs.c b/com32/tools/relocs.c
index 028ff315..19eb6654 100644
--- a/com32/tools/relocs.c
+++ b/com32/tools/relocs.c
@@ -1,3 +1,6 @@
+/*
+ * This file is taken from the Linux kernel and is distributed under GPL v2.
+ */
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
@@ -9,6 +12,8 @@
#include <byteswap.h>
#define USE_BSD
#include <endian.h>
+#include <regex.h>
+#include <sys/types.h>
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
static Elf32_Ehdr ehdr;
@@ -24,40 +29,60 @@ struct section {
};
static struct section *secs;
+static void die(char *fmt, ...)
+{
+ va_list ap;
+ va_start(ap, fmt);
+ vfprintf(stderr, fmt, ap);
+ va_end(ap);
+ exit(1);
+}
+
/*
- * Following symbols have been audited. There values are constant and do
- * not change if bzImage is loaded at a different physical address than
- * the address for which it has been compiled. Don't warn user about
+ * Following symbols have been audited. Don't warn user about
* absolute relocations present w.r.t these symbols.
*/
-static const char* safe_abs_relocs[] = {
- "xen_irq_disable_direct_reloc",
- "xen_save_fl_direct_reloc",
-};
-static int is_safe_abs_reloc(const char* sym_name)
+/* True absolute relocations */
+
+static const char safe_abs_regex[] =
+"^(__.*_len|__.*_dwords)$";
+static regex_t safe_abs_regex_c;
+
+static int is_safe_abs_reloc(const char *sym_name)
{
- int i;
+ return !regexec(&safe_abs_regex_c, sym_name, 0, NULL, 0);
+}
- for (i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
- if (!strcmp(sym_name, safe_abs_relocs[i]))
- /* Match found */
- return 1;
- }
- if (strncmp(sym_name, "VDSO", 4) == 0)
- return 1;
- if (strncmp(sym_name, "__crc_", 6) == 0)
- return 1;
- return 0;
+/* These are relative even though the linker marks them absolute */
+
+static const char safe_rel_regex[] =
+"^(__.*_start|__.*_end|_end|_[se](text|data))$";
+static regex_t safe_rel_regex_c;
+
+static int is_safe_rel_reloc(const char *sym_name)
+{
+ return !regexec(&safe_rel_regex_c, sym_name, 0, NULL, 0);
}
-static void die(char *fmt, ...)
+static void regex_init(void)
{
- va_list ap;
- va_start(ap, fmt);
- vfprintf(stderr, fmt, ap);
- va_end(ap);
- exit(1);
+ char errbuf[128];
+ int err;
+
+ err = regcomp(&safe_abs_regex_c, safe_abs_regex,
+ REG_EXTENDED|REG_NOSUB);
+ if (err) {
+ regerror(err, &safe_abs_regex_c, errbuf, sizeof errbuf);
+ die("%s", errbuf);
+ }
+
+ err = regcomp(&safe_rel_regex_c, safe_rel_regex,
+ REG_EXTENDED|REG_NOSUB);
+ if (err) {
+ regerror(err, &safe_rel_regex_c, errbuf, sizeof errbuf);
+ die("%s", errbuf);
+ }
}
static const char *sym_type(unsigned type)
@@ -404,7 +429,7 @@ static void print_absolute_symbols(void)
printf("\n");
}
-static void print_absolute_relocs(void)
+static int print_absolute_relocs(FILE *f)
{
int i, printed = 0;
@@ -448,18 +473,17 @@ static void print_absolute_relocs(void)
* Before warning check if this absolute symbol
* relocation is harmless.
*/
- if (is_safe_abs_reloc(name))
+ if (is_safe_abs_reloc(name) ||
+ is_safe_rel_reloc(name))
continue;
if (!printed) {
- printf("WARNING: Absolute relocations"
- " present\n");
- printf("Offset Info Type Sym.Value "
- "Sym.Name\n");
+ fprintf(f, "Unknown absolute relocations present\n");
+ fprintf(f, "Offset Info Type Sym.Value Sym.Name\n");
printed = 1;
}
- printf("%08x %08x %10s %08x %s\n",
+ fprintf(f, "%08x %08x %10s %08x %s\n",
rel->r_offset,
rel->r_info,
rel_type(ELF32_R_TYPE(rel->r_info)),
@@ -469,7 +493,9 @@ static void print_absolute_relocs(void)
}
if (printed)
- printf("\n");
+ fputc('\n', f);
+
+ return printed;
}
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
@@ -501,9 +527,10 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
r_type = ELF32_R_TYPE(rel->r_info);
/* Don't visit relocations to absolute symbols */
- if (sym->st_shndx == SHN_ABS) {
+ if (sym->st_shndx == SHN_ABS &&
+ !is_safe_rel_reloc(sym_name(sym_strtab, sym)))
continue;
- }
+
switch (r_type) {
case R_386_PC32:
case R_386_GOTPC:
@@ -527,11 +554,14 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
+ (void)rel; (void)sym;
reloc_count += 1;
}
static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
{
+ (void)sym;
+
/* Remember the address that needs to be adjusted. */
relocs[reloc_idx++] = rel->r_offset;
}
@@ -601,6 +631,7 @@ int main(int argc, char **argv)
const char *fname;
FILE *fp;
int i;
+ int err = 0;
show_absolute_syms = 0;
show_absolute_relocs = 0;
@@ -632,6 +663,10 @@ int main(int argc, char **argv)
if (!fname) {
usage();
}
+
+
+ regex_init();
+
fp = fopen(fname, "r");
if (!fp) {
die("Cannot open %s: %s\n",
@@ -647,9 +682,10 @@ int main(int argc, char **argv)
return 0;
}
if (show_absolute_relocs) {
- print_absolute_relocs();
+ print_absolute_relocs(stdout);
return 0;
}
+ err = print_absolute_relocs(stderr);
emit_relocs(as_text);
- return 0;
+ return err;
}