x86: remove arbitrary ELF section limit in i386 relocatable kernel

Impact: build failure in maximal configurations

The 32-bit x86 relocatable kernel requires an auxilliary host program
to process the relocations.  This program had a hard-coded arbitrary
limit of a 100 ELF sections.  Instead of a hard-coded limit, allocate
the structures dynamically.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

1 files changed, 110 insertions, 88 deletions

diff --git a/arch/x86/boot/compressed/relocs.c b/arch/x86/boot/compressed/relocs.c
index edaadea90aaf..a1310c52fc0c 100644
--- a/arch/x86/boot/compressed/relocs.c
+++ b/arch/x86/boot/compressed/relocs.c
@@ -10,16 +10,20 @@
 #define USE_BSD
 #include <endian.h>
 
-#define MAX_SHDRS 100
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 static Elf32_Ehdr ehdr;
-static Elf32_Shdr shdr[MAX_SHDRS];
-static Elf32_Sym  *symtab[MAX_SHDRS];
-static Elf32_Rel  *reltab[MAX_SHDRS];
-static char *strtab[MAX_SHDRS];
 static unsigned long reloc_count, reloc_idx;
 static unsigned long *relocs;
 
+struct section {
+        Elf32_Shdr     shdr;
+        struct section *link;
+        Elf32_Sym      *symtab;
+        Elf32_Rel      *reltab;
+        char           *strtab;
+};
+static struct section *secs;
+
 /*
  * Following symbols have been audited. There values are constant and do
  * not change if bzImage is loaded at a different physical address than
@@ -35,7 +39,7 @@ static int is_safe_abs_reloc(const char* sym_name)
 {
         int i;
 
-        for(i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
+        for (i = 0; i < ARRAY_SIZE(safe_abs_relocs); i++) {
                 if (!strcmp(sym_name, safe_abs_relocs[i]))
                         /* Match found */
                         return 1;
@@ -137,10 +141,10 @@ static const char *sec_name(unsigned shndx)
 {
         const char *sec_strtab;
         const char *name;
-        sec_strtab = strtab[ehdr.e_shstrndx];
+        sec_strtab = secs[ehdr.e_shstrndx].strtab;
         name = "<noname>";
         if (shndx < ehdr.e_shnum) {
-                name = sec_strtab + shdr[shndx].sh_name;
+                name = sec_strtab + secs[shndx].shdr.sh_name;
         }
         else if (shndx == SHN_ABS) {
                 name = "ABSOLUTE";
@@ -159,7 +163,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
                 name = sym_strtab + sym->st_name;
         }
         else {
-                name = sec_name(shdr[sym->st_shndx].sh_name);
+                name = sec_name(secs[sym->st_shndx].shdr.sh_name);
         }
         return name;
 }
@@ -244,29 +248,34 @@ static void read_ehdr(FILE *fp)
 static void read_shdrs(FILE *fp)
 {
         int i;
-        if (ehdr.e_shnum > MAX_SHDRS) {
-                die("%d section headers supported: %d\n",
-                        ehdr.e_shnum, MAX_SHDRS);
+        Elf32_Shdr shdr;
+
+        secs = calloc(ehdr.e_shnum, sizeof(struct section));
+        if (!secs) {
+                die("Unable to allocate %d section headers\n",
+                    ehdr.e_shnum);
         }
         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
                 die("Seek to %d failed: %s\n",
                         ehdr.e_shoff, strerror(errno));
         }
-        if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
-                die("Cannot read ELF section headers: %s\n",
-                        strerror(errno));
-        }
-        for(i = 0; i < ehdr.e_shnum; i++) {
-                shdr[i].sh_name      = elf32_to_cpu(shdr[i].sh_name);
-                shdr[i].sh_type      = elf32_to_cpu(shdr[i].sh_type);
-                shdr[i].sh_flags     = elf32_to_cpu(shdr[i].sh_flags);
-                shdr[i].sh_addr      = elf32_to_cpu(shdr[i].sh_addr);
-                shdr[i].sh_offset    = elf32_to_cpu(shdr[i].sh_offset);
-                shdr[i].sh_size      = elf32_to_cpu(shdr[i].sh_size);
-                shdr[i].sh_link      = elf32_to_cpu(shdr[i].sh_link);
-                shdr[i].sh_info      = elf32_to_cpu(shdr[i].sh_info);
-                shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
-                shdr[i].sh_entsize   = elf32_to_cpu(shdr[i].sh_entsize);
+        for (i = 0; i < ehdr.e_shnum; i++) {
+                struct section *sec = &secs[i];
+                if (fread(&shdr, sizeof shdr, 1, fp) != 1)
+                        die("Cannot read ELF section headers %d/%d: %s\n",
+                            i, ehdr.e_shnum, strerror(errno));
+                sec->shdr.sh_name      = elf32_to_cpu(shdr.sh_name);
+                sec->shdr.sh_type      = elf32_to_cpu(shdr.sh_type);
+                sec->shdr.sh_flags     = elf32_to_cpu(shdr.sh_flags);
+                sec->shdr.sh_addr      = elf32_to_cpu(shdr.sh_addr);
+                sec->shdr.sh_offset    = elf32_to_cpu(shdr.sh_offset);
+                sec->shdr.sh_size      = elf32_to_cpu(shdr.sh_size);
+                sec->shdr.sh_link      = elf32_to_cpu(shdr.sh_link);
+                sec->shdr.sh_info      = elf32_to_cpu(shdr.sh_info);
+                sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
+                sec->shdr.sh_entsize   = elf32_to_cpu(shdr.sh_entsize);
+                if (sec->shdr.sh_link < ehdr.e_shnum)
+                        sec->link = &secs[sec->shdr.sh_link];
         }
 
 }
@@ -274,20 +283,22 @@ static void read_shdrs(FILE *fp)
 static void read_strtabs(FILE *fp)
 {
         int i;
-        for(i = 0; i < ehdr.e_shnum; i++) {
-                if (shdr[i].sh_type != SHT_STRTAB) {
+        for (i = 0; i < ehdr.e_shnum; i++) {
+                struct section *sec = &secs[i];
+                if (sec->shdr.sh_type != SHT_STRTAB) {
                         continue;
                 }
-                strtab[i] = malloc(shdr[i].sh_size);
-                if (!strtab[i]) {
+                sec->strtab = malloc(sec->shdr.sh_size);
+                if (!sec->strtab) {
                         die("malloc of %d bytes for strtab failed\n",
-                                shdr[i].sh_size);
+                                sec->shdr.sh_size);
                 }
-                if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
+                if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
                         die("Seek to %d failed: %s\n",
-                                shdr[i].sh_offset, strerror(errno));
+                                sec->shdr.sh_offset, strerror(errno));
                 }
-                if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
+                if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
+                    != sec->shdr.sh_size) {
                         die("Cannot read symbol table: %s\n",
                                 strerror(errno));
                 }
@@ -297,28 +308,31 @@ static void read_strtabs(FILE *fp)
 static void read_symtabs(FILE *fp)
 {
         int i,j;
-        for(i = 0; i < ehdr.e_shnum; i++) {
-                if (shdr[i].sh_type != SHT_SYMTAB) {
+        for (i = 0; i < ehdr.e_shnum; i++) {
+                struct section *sec = &secs[i];
+                if (sec->shdr.sh_type != SHT_SYMTAB) {
                         continue;
                 }
-                symtab[i] = malloc(shdr[i].sh_size);
-                if (!symtab[i]) {
+                sec->symtab = malloc(sec->shdr.sh_size);
+                if (!sec->symtab) {
                         die("malloc of %d bytes for symtab failed\n",
-                                shdr[i].sh_size);
+                                sec->shdr.sh_size);
                 }
-                if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
+                if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
                         die("Seek to %d failed: %s\n",
-                                shdr[i].sh_offset, strerror(errno));
+                                sec->shdr.sh_offset, strerror(errno));
                 }
-                if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
+                if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
+                    != sec->shdr.sh_size) {
                         die("Cannot read symbol table: %s\n",
                                 strerror(errno));
                 }
-                for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
-                        symtab[i][j].st_name  = elf32_to_cpu(symtab[i][j].st_name);
-                        symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
-                        symtab[i][j].st_size  = elf32_to_cpu(symtab[i][j].st_size);
-                        symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
+                for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
+                        Elf32_Sym *sym = &sec->symtab[j];
+                        sym->st_name  = elf32_to_cpu(sym->st_name);
+                        sym->st_value = elf32_to_cpu(sym->st_value);
+                        sym->st_size  = elf32_to_cpu(sym->st_size);
+                        sym->st_shndx = elf16_to_cpu(sym->st_shndx);
                 }
         }
 }
@@ -327,26 +341,29 @@ static void read_symtabs(FILE *fp)
 static void read_relocs(FILE *fp)
 {
         int i,j;
-        for(i = 0; i < ehdr.e_shnum; i++) {
-                if (shdr[i].sh_type != SHT_REL) {
+        for (i = 0; i < ehdr.e_shnum; i++) {
+                struct section *sec = &secs[i];
+                if (sec->shdr.sh_type != SHT_REL) {
                         continue;
                 }
-                reltab[i] = malloc(shdr[i].sh_size);
-                if (!reltab[i]) {
+                sec->reltab = malloc(sec->shdr.sh_size);
+                if (!sec->reltab) {
                         die("malloc of %d bytes for relocs failed\n",
-                                shdr[i].sh_size);
+                                sec->shdr.sh_size);
                 }
-                if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
+                if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
                         die("Seek to %d failed: %s\n",
-                                shdr[i].sh_offset, strerror(errno));
+                                sec->shdr.sh_offset, strerror(errno));
                 }
-                if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
+                if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
+                    != sec->shdr.sh_size) {
                         die("Cannot read symbol table: %s\n",
                                 strerror(errno));
                 }
-                for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
-                        reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
-                        reltab[i][j].r_info   = elf32_to_cpu(reltab[i][j].r_info);
+                for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
+                        Elf32_Rel *rel = &sec->reltab[j];
+                        rel->r_offset = elf32_to_cpu(rel->r_offset);
+                        rel->r_info   = elf32_to_cpu(rel->r_info);
                 }
         }
 }
@@ -357,19 +374,21 @@ static void print_absolute_symbols(void)
         int i;
         printf("Absolute symbols\n");
         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
-        for(i = 0; i < ehdr.e_shnum; i++) {
+        for (i = 0; i < ehdr.e_shnum; i++) {
+                struct section *sec = &secs[i];
                 char *sym_strtab;
                 Elf32_Sym *sh_symtab;
                 int j;
-                if (shdr[i].sh_type != SHT_SYMTAB) {
+
+                if (sec->shdr.sh_type != SHT_SYMTAB) {
                         continue;
                 }
-                sh_symtab = symtab[i];
-                sym_strtab = strtab[shdr[i].sh_link];
-                for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
+                sh_symtab = sec->symtab;
+                sym_strtab = sec->link->strtab;
+                for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
                         Elf32_Sym *sym;
                         const char *name;
-                        sym = &symtab[i][j];
+                        sym = &sec->symtab[j];
                         name = sym_name(sym_strtab, sym);
                         if (sym->st_shndx != SHN_ABS) {
                                 continue;
@@ -389,26 +408,27 @@ static void print_absolute_relocs(void)
 {
         int i, printed = 0;
 
-        for(i = 0; i < ehdr.e_shnum; i++) {
+        for (i = 0; i < ehdr.e_shnum; i++) {
+                struct section *sec = &secs[i];
+                struct section *sec_applies, *sec_symtab;
                 char *sym_strtab;
                 Elf32_Sym *sh_symtab;
-                unsigned sec_applies, sec_symtab;
                 int j;
-                if (shdr[i].sh_type != SHT_REL) {
+                if (sec->shdr.sh_type != SHT_REL) {
                         continue;
                 }
-                sec_symtab  = shdr[i].sh_link;
-                sec_applies = shdr[i].sh_info;
-                if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
+                sec_symtab  = sec->link;
+                sec_applies = &secs[sec->shdr.sh_info];
+                if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
                         continue;
                 }
-                sh_symtab = symtab[sec_symtab];
-                sym_strtab = strtab[shdr[sec_symtab].sh_link];
-                for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
+                sh_symtab  = sec_symtab->symtab;
+                sym_strtab = sec_symtab->link->strtab;
+                for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
                         Elf32_Rel *rel;
                         Elf32_Sym *sym;
                         const char *name;
-                        rel = &reltab[i][j];
+                        rel = &sec->reltab[j];
                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
                         name = sym_name(sym_strtab, sym);
                         if (sym->st_shndx != SHN_ABS) {
@@ -456,26 +476,28 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
 {
         int i;
         /* Walk through the relocations */
-        for(i = 0; i < ehdr.e_shnum; i++) {
+        for (i = 0; i < ehdr.e_shnum; i++) {
                 char *sym_strtab;
                 Elf32_Sym *sh_symtab;
-                unsigned sec_applies, sec_symtab;
+                struct section *sec_applies, *sec_symtab;
                 int j;
-                if (shdr[i].sh_type != SHT_REL) {
+                struct section *sec = &secs[i];
+
+                if (sec->shdr.sh_type != SHT_REL) {
                         continue;
                 }
-                sec_symtab  = shdr[i].sh_link;
-                sec_applies = shdr[i].sh_info;
-                if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
+                sec_symtab  = sec->link;
+                sec_applies = &secs[sec->shdr.sh_info];
+                if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
                         continue;
                 }
-                sh_symtab = symtab[sec_symtab];
-                sym_strtab = strtab[shdr[sec_symtab].sh_link];
-                for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
+                sh_symtab = sec_symtab->symtab;
+                sym_strtab = sec->link->strtab;
+                for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
                         Elf32_Rel *rel;
                         Elf32_Sym *sym;
                         unsigned r_type;
-                        rel = &reltab[i][j];
+                        rel = &sec->reltab[j];
                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
                         r_type = ELF32_R_TYPE(rel->r_info);
                         /* Don't visit relocations to absolute symbols */
@@ -539,7 +561,7 @@ static void emit_relocs(int as_text)
                  */
                 printf(".section \".data.reloc\",\"a\"\n");
                 printf(".balign 4\n");
-                for(i = 0; i < reloc_count; i++) {
+                for (i = 0; i < reloc_count; i++) {
                         printf("\t .long 0x%08lx\n", relocs[i]);
                 }
                 printf("\n");
@@ -550,7 +572,7 @@ static void emit_relocs(int as_text)
                 /* Print a stop */
                 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
                 /* Now print each relocation */
-                for(i = 0; i < reloc_count; i++) {
+                for (i = 0; i < reloc_count; i++) {
                         buf[0] = (relocs[i] >>  0) & 0xff;
                         buf[1] = (relocs[i] >>  8) & 0xff;
                         buf[2] = (relocs[i] >> 16) & 0xff;
@@ -577,7 +599,7 @@ int main(int argc, char **argv)
         show_absolute_relocs = 0;
         as_text = 0;
         fname = NULL;
-        for(i = 1; i < argc; i++) {
+        for (i = 1; i < argc; i++) {
                 char *arg = argv[i];
                 if (*arg == '-') {
                         if (strcmp(argv[1], "--abs-syms") == 0) {