x86,vdso: Fix cross-compilation from big-endian architectures

This adds a macro GET(x) to convert x from big-endian to
little-endian.  Hopefully I put it everywhere it needs to go and got
all the cases needed for everyone's linux/elf.h.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>

diff --git a/arch/x86/vdso/vdso2c.c b/arch/x86/vdso/vdso2c.c
index fe8bfbf62612d1a453e26ca12c22ab94ddb7f53b..de19ced6c87d69970ba6962a041c0101d3c108c4 100644 (file)
--- a/arch/x86/vdso/vdso2c.c
+++ b/arch/x86/vdso/vdso2c.c
@@ -51,6 +51,21 @@ static void fail(const char *format, ...)
        va_end(ap);
 }
 
+/*
+ * Evil macros to do a little-endian read.
+ */
+#define __GET_TYPE(x, type, bits, ifnot)                               \
+       __builtin_choose_expr(                                          \
+               __builtin_types_compatible_p(typeof(x), type),          \
+               le##bits##toh((x)), ifnot)
+
+extern void bad_get(uint64_t);
+
+#define GET(x)                                                         \
+       __GET_TYPE((x), __u32, 32, __GET_TYPE((x), __u64, 64,           \
+       __GET_TYPE((x), __s32, 32, __GET_TYPE((x), __s64, 64,           \
+       __GET_TYPE((x), __u16, 16, bad_get(x))))))
+
 #define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))
 
 #define BITS 64

diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index 26a7c1fa745236982c9232d9a824a44841e4d45e..dadecb9d5ce8f50edecc4b683dc6e71a52303927 100644 (file)
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -18,25 +18,27 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
        const char *secstrings;
        uint64_t syms[NSYMS] = {};
 
-       Elf_Phdr *pt = (Elf_Phdr *)(addr + hdr->e_phoff);
+       Elf_Phdr *pt = (Elf_Phdr *)(addr + GET(hdr->e_phoff));
 
        /* Walk the segment table. */
-       for (i = 0; i < hdr->e_phnum; i++) {
-               if (pt[i].p_type == PT_LOAD) {
+       for (i = 0; i < GET(hdr->e_phnum); i++) {
+               if (GET(pt[i].p_type) == PT_LOAD) {
                        if (found_load)
                                fail("multiple PT_LOAD segs\n");
 
-                       if (pt[i].p_offset != 0 || pt[i].p_vaddr != 0)
+                       if (GET(pt[i].p_offset) != 0 ||
+                           GET(pt[i].p_vaddr) != 0)
                                fail("PT_LOAD in wrong place\n");
 
-                       if (pt[i].p_memsz != pt[i].p_filesz)
+                       if (GET(pt[i].p_memsz) != GET(pt[i].p_filesz))
                                fail("cannot handle memsz != filesz\n");
 
-                       load_size = pt[i].p_memsz;
+                       load_size = GET(pt[i].p_memsz);
                        found_load = 1;
-               } else if (pt[i].p_type == PT_DYNAMIC) {
-                       dyn = addr + pt[i].p_offset;
-                       dyn_end = addr + pt[i].p_offset + pt[i].p_memsz;
+               } else if (GET(pt[i].p_type) == PT_DYNAMIC) {
+                       dyn = addr + GET(pt[i].p_offset);
+                       dyn_end = addr + GET(pt[i].p_offset) +
+                               GET(pt[i].p_memsz);
                }
        }
        if (!found_load)
@@ -44,43 +46,48 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
        data_size = (load_size + 4095) / 4096 * 4096;
 
        /* Walk the dynamic table */
-       for (i = 0; dyn + i < dyn_end && dyn[i].d_tag != DT_NULL; i++) {
-               if (dyn[i].d_tag == DT_REL || dyn[i].d_tag == DT_RELSZ ||
-                   dyn[i].d_tag == DT_RELENT || dyn[i].d_tag == DT_TEXTREL)
+       for (i = 0; dyn + i < dyn_end && GET(dyn[i].d_tag) != DT_NULL; i++) {
+               typeof(dyn[i].d_tag) tag = GET(dyn[i].d_tag);
+               if (tag == DT_REL || tag == DT_RELSZ ||
+                   tag == DT_RELENT || tag == DT_TEXTREL)
                        fail("vdso image contains dynamic relocations\n");
        }
 
        /* Walk the section table */
-       secstrings_hdr = addr + hdr->e_shoff + hdr->e_shentsize*hdr->e_shstrndx;
-       secstrings = addr + secstrings_hdr->sh_offset;
-       for (i = 0; i < hdr->e_shnum; i++) {
-               Elf_Shdr *sh = addr + hdr->e_shoff + hdr->e_shentsize * i;
-               if (sh->sh_type == SHT_SYMTAB)
+       secstrings_hdr = addr + GET(hdr->e_shoff) +
+               GET(hdr->e_shentsize)*GET(hdr->e_shstrndx);
+       secstrings = addr + GET(secstrings_hdr->sh_offset);
+       for (i = 0; i < GET(hdr->e_shnum); i++) {
+               Elf_Shdr *sh = addr + GET(hdr->e_shoff) +
+                       GET(hdr->e_shentsize) * i;
+               if (GET(sh->sh_type) == SHT_SYMTAB)
                        symtab_hdr = sh;
 
-               if (!strcmp(secstrings + sh->sh_name, ".altinstructions"))
+               if (!strcmp(secstrings + GET(sh->sh_name), ".altinstructions"))
                        alt_sec = sh;
        }
 
        if (!symtab_hdr)
                fail("no symbol table\n");
 
-       strtab_hdr = addr + hdr->e_shoff +
-               hdr->e_shentsize * symtab_hdr->sh_link;
+       strtab_hdr = addr + GET(hdr->e_shoff) +
+               GET(hdr->e_shentsize) * GET(symtab_hdr->sh_link);
 
        /* Walk the symbol table */
-       for (i = 0; i < symtab_hdr->sh_size / symtab_hdr->sh_entsize; i++) {
+       for (i = 0; i < GET(symtab_hdr->sh_size) / GET(symtab_hdr->sh_entsize);
+            i++) {
                int k;
-               Elf_Sym *sym = addr + symtab_hdr->sh_offset +
-                       symtab_hdr->sh_entsize * i;
-               const char *name = addr + strtab_hdr->sh_offset + sym->st_name;
+               Elf_Sym *sym = addr + GET(symtab_hdr->sh_offset) +
+                       GET(symtab_hdr->sh_entsize) * i;
+               const char *name = addr + GET(strtab_hdr->sh_offset) +
+                       GET(sym->st_name);
                for (k = 0; k < NSYMS; k++) {
                        if (!strcmp(name, required_syms[k])) {
                                if (syms[k]) {
                                        fail("duplicate symbol %s\n",
                                             required_syms[k]);
                                }
-                               syms[k] = sym->st_value;
+                               syms[k] = GET(sym->st_value);
                        }
                }
        }
@@ -106,7 +113,7 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
        hdr->e_shoff = 0;
        hdr->e_shentsize = 0;
        hdr->e_shnum = 0;
-       hdr->e_shstrndx = SHN_UNDEF;
+       hdr->e_shstrndx = htole16(SHN_UNDEF);
 
        if (!name) {
                fwrite(addr, load_size, 1, outfile);