[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] [RFC v2 21/23] x86/relocs: Add option to generate 64-bit relocations



The x86 relocation tool generates a list of 32-bit signed integers. There
was no need to use 64-bit integers because all addresses where above the 2G
top of the memory.

This change add a large-reloc option to generate 64-bit unsigned integers.
It can be used when the kernel plan to go below the top 2G and 32-bit
integers are not enough.

Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx>
---
 arch/x86/tools/relocs.c        | 60 +++++++++++++++++++++++++++++++++---------
 arch/x86/tools/relocs.h        |  4 +--
 arch/x86/tools/relocs_common.c | 15 +++++++----
 3 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 70f523dd68ff..19b3e6c594b1 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -12,8 +12,14 @@
 
 static Elf_Ehdr ehdr;
 
+#if ELF_BITS == 64
+typedef uint64_t rel_off_t;
+#else
+typedef uint32_t rel_off_t;
+#endif
+
 struct relocs {
-       uint32_t        *offset;
+       rel_off_t       *offset;
        unsigned long   count;
        unsigned long   size;
 };
@@ -627,7 +633,7 @@ static void print_absolute_relocs(void)
                printf("\n");
 }
 
-static void add_reloc(struct relocs *r, uint32_t offset)
+static void add_reloc(struct relocs *r, rel_off_t offset)
 {
        if (r->count == r->size) {
                unsigned long newsize = r->size + 50000;
@@ -983,26 +989,48 @@ static void sort_relocs(struct relocs *r)
        qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 }
 
-static int write32(uint32_t v, FILE *f)
+static int write32(rel_off_t rel, FILE *f)
 {
-       unsigned char buf[4];
+       unsigned char buf[sizeof(uint32_t)];
+       uint32_t v = (uint32_t)rel;
 
        put_unaligned_le32(v, buf);
-       return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
+       return fwrite(buf, 1, sizeof(buf), f) == sizeof(buf) ? 0 : -1;
 }
 
-static int write32_as_text(uint32_t v, FILE *f)
+static int write32_as_text(rel_off_t rel, FILE *f)
 {
+       uint32_t v = (uint32_t)rel;
        return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 }
 
-static void emit_relocs(int as_text, int use_real_mode)
+static int write64(rel_off_t rel, FILE *f)
+{
+       unsigned char buf[sizeof(uint64_t)];
+       uint64_t v = (uint64_t)rel;
+
+       put_unaligned_le64(v, buf);
+       return fwrite(buf, 1, sizeof(buf), f) == sizeof(buf) ? 0 : -1;
+}
+
+static int write64_as_text(rel_off_t rel, FILE *f)
+{
+       uint64_t v = (uint64_t)rel;
+       return fprintf(f, "\t.quad 0x%016"PRIx64"\n", v) > 0 ? 0 : -1;
+}
+
+static void emit_relocs(int as_text, int use_real_mode, int use_large_reloc)
 {
        int i;
-       int (*write_reloc)(uint32_t, FILE *) = write32;
+       int (*write_reloc)(rel_off_t, FILE *);
        int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
                        const char *symname);
 
+       if (use_large_reloc)
+               write_reloc = write64;
+       else
+               write_reloc = write32;
+
 #if ELF_BITS == 64
        if (!use_real_mode)
                do_reloc = do_reloc64;
@@ -1013,6 +1041,9 @@ static void emit_relocs(int as_text, int use_real_mode)
                do_reloc = do_reloc32;
        else
                do_reloc = do_reloc_real;
+
+       /* Large relocations only for 64-bit */
+       use_large_reloc = 0;
 #endif
 
        /* Collect up the relocations */
@@ -1036,8 +1067,13 @@ static void emit_relocs(int as_text, int use_real_mode)
                 * gas will like.
                 */
                printf(".section \".data.reloc\",\"a\"\n");
-               printf(".balign 4\n");
-               write_reloc = write32_as_text;
+               if (use_large_reloc) {
+                       printf(".balign 8\n");
+                       write_reloc = write64_as_text;
+               } else {
+                       printf(".balign 4\n");
+                       write_reloc = write32_as_text;
+               }
        }
 
        if (use_real_mode) {
@@ -1131,7 +1167,7 @@ static void print_reloc_info(void)
 
 void process(FILE *fp, int use_real_mode, int as_text,
             int show_absolute_syms, int show_absolute_relocs,
-            int show_reloc_info)
+            int show_reloc_info, int use_large_reloc)
 {
        regex_init(use_real_mode);
        read_ehdr(fp);
@@ -1153,5 +1189,5 @@ void process(FILE *fp, int use_real_mode, int as_text,
                print_reloc_info();
                return;
        }
-       emit_relocs(as_text, use_real_mode);
+       emit_relocs(as_text, use_real_mode, use_large_reloc);
 }
diff --git a/arch/x86/tools/relocs.h b/arch/x86/tools/relocs.h
index 1d23bf953a4a..cb771cc4412d 100644
--- a/arch/x86/tools/relocs.h
+++ b/arch/x86/tools/relocs.h
@@ -30,8 +30,8 @@ enum symtype {
 
 void process_32(FILE *fp, int use_real_mode, int as_text,
                int show_absolute_syms, int show_absolute_relocs,
-               int show_reloc_info);
+               int show_reloc_info, int use_large_reloc);
 void process_64(FILE *fp, int use_real_mode, int as_text,
                int show_absolute_syms, int show_absolute_relocs,
-               int show_reloc_info);
+               int show_reloc_info, int use_large_reloc);
 #endif /* RELOCS_H */
diff --git a/arch/x86/tools/relocs_common.c b/arch/x86/tools/relocs_common.c
index acab636bcb34..9cf1391af50a 100644
--- a/arch/x86/tools/relocs_common.c
+++ b/arch/x86/tools/relocs_common.c
@@ -11,14 +11,14 @@ void die(char *fmt, ...)
 
 static void usage(void)
 {
-       die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode]" \
-           " vmlinux\n");
+       die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode|" \
+           "--large-reloc]  vmlinux\n");
 }
 
 int main(int argc, char **argv)
 {
        int show_absolute_syms, show_absolute_relocs, show_reloc_info;
-       int as_text, use_real_mode;
+       int as_text, use_real_mode, use_large_reloc;
        const char *fname;
        FILE *fp;
        int i;
@@ -29,6 +29,7 @@ int main(int argc, char **argv)
        show_reloc_info = 0;
        as_text = 0;
        use_real_mode = 0;
+       use_large_reloc = 0;
        fname = NULL;
        for (i = 1; i < argc; i++) {
                char *arg = argv[i];
@@ -53,6 +54,10 @@ int main(int argc, char **argv)
                                use_real_mode = 1;
                                continue;
                        }
+                       if (strcmp(arg, "--large-reloc") == 0) {
+                               use_large_reloc = 1;
+                               continue;
+                       }
                }
                else if (!fname) {
                        fname = arg;
@@ -74,11 +79,11 @@ int main(int argc, char **argv)
        if (e_ident[EI_CLASS] == ELFCLASS64)
                process_64(fp, use_real_mode, as_text,
                           show_absolute_syms, show_absolute_relocs,
-                          show_reloc_info);
+                          show_reloc_info, use_large_reloc);
        else
                process_32(fp, use_real_mode, as_text,
                           show_absolute_syms, show_absolute_relocs,
-                          show_reloc_info);
+                          show_reloc_info, use_large_reloc);
        fclose(fp);
        return 0;
 }
-- 
2.14.0.434.g98096fd7a8-goog


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.