1 files changed, 135 insertions, 81 deletions

diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 44138c3e6ea7..9013243cecca 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -6,6 +6,7 @@
  *
  *    Linux/PA-RISC Project (http://www.parisc-linux.org/)
  *    Copyright (C) 2003 Randolph Chung <tausq at debian . org>
+ *    Copyright (C) 2008 Helge Deller <deller@gmx.de>
  *
  *
  *    This program is free software; you can redistribute it and/or modify
@@ -24,6 +25,19 @@
  *
  *
  *    Notes:
+ *    - PLT stub handling
+ *      On 32bit (and sometimes 64bit) and with big kernel modules like xfs or
+ *      ipv6 the relocation types R_PARISC_PCREL17F and R_PARISC_PCREL22F may
+ *      fail to reach their PLT stub if we only create one big stub array for
+ *      all sections at the beginning of the core or init section.
+ *      Instead we now insert individual PLT stub entries directly in front of
+ *      of the code sections where the stubs are actually called.
+ *      This reduces the distance between the PCREL location and the stub entry
+ *      so that the relocations can be fulfilled.
+ *      While calculating the final layout of the kernel module in memory, the
+ *      kernel module loader calls arch_mod_section_prepend() to request the
+ *      to be reserved amount of memory in front of each individual section.
+ *
  *    - SEGREL32 handling
  *      We are not doing SEGREL32 handling correctly. According to the ABI, we
  *      should do a value offset, like this:
@@ -58,9 +72,13 @@
 #define DEBUGP(fmt...)
 #endif
 
+#define RELOC_REACHABLE(val, bits) \
+        (( ( !((val) & (1<<((bits)-1))) && ((val)>>(bits)) != 0 )  ||   \
+             ( ((val) & (1<<((bits)-1))) && ((val)>>(bits)) != (((__typeof__(val))(~0))>>((bits)+2)))) ? \
+        0 : 1)
+
 #define CHECK_RELOC(val, bits) \
-        if ( ( !((val) & (1<<((bits)-1))) && ((val)>>(bits)) != 0 )  || \
-             ( ((val) & (1<<((bits)-1))) && ((val)>>(bits)) != (((__typeof__(val))(~0))>>((bits)+2)))) { \
+        if (!RELOC_REACHABLE(val, bits)) { \
                 printk(KERN_ERR "module %s relocation of symbol %s is out of range (0x%lx in %d bits)\n", \
                 me->name, strtab + sym->st_name, (unsigned long)val, bits); \
                 return -ENOEXEC;                        \
@@ -92,13 +110,6 @@ static inline int in_local(struct module *me, void *loc)
         return in_init(me, loc) || in_core(me, loc);
 }
 
-static inline int in_local_section(struct module *me, void *loc, void *dot)
-{
-        return (in_init(me, loc) && in_init(me, dot)) ||
-                (in_core(me, loc) && in_core(me, dot));
-}
-
-
 #ifndef CONFIG_64BIT
 struct got_entry {
         Elf32_Addr addr;
@@ -258,23 +269,42 @@ static inline unsigned long count_stubs(const Elf_Rela *rela, unsigned long n)
 /* Free memory returned from module_alloc */
 void module_free(struct module *mod, void *module_region)
 {
+        kfree(mod->arch.section);
+        mod->arch.section = NULL;
+
         vfree(module_region);
         /* FIXME: If module_region == mod->init_region, trim exception
            table entries. */
 }
 
+/* Additional bytes needed in front of individual sections */
+unsigned int arch_mod_section_prepend(struct module *mod,
+                                      unsigned int section)
+{
+        /* size needed for all stubs of this section (including
+         * one additional for correct alignment of the stubs) */
+        return (mod->arch.section[section].stub_entries + 1)
+                * sizeof(struct stub_entry);
+}
+
 #define CONST 
 int module_frob_arch_sections(CONST Elf_Ehdr *hdr,
                               CONST Elf_Shdr *sechdrs,
                               CONST char *secstrings,
                               struct module *me)
 {
-        unsigned long gots = 0, fdescs = 0, stubs = 0, init_stubs = 0;
+        unsigned long gots = 0, fdescs = 0, len;
         unsigned int i;
 
+        len = hdr->e_shnum * sizeof(me->arch.section[0]);
+        me->arch.section = kzalloc(len, GFP_KERNEL);
+        if (!me->arch.section)
+                return -ENOMEM;
+
         for (i = 1; i < hdr->e_shnum; i++) {
-                const Elf_Rela *rels = (void *)hdr + sechdrs[i].sh_offset;
+                const Elf_Rela *rels = (void *)sechdrs[i].sh_addr;
                 unsigned long nrels = sechdrs[i].sh_size / sizeof(*rels);
+                unsigned int count, s;
 
                 if (strncmp(secstrings + sechdrs[i].sh_name,
                             ".PARISC.unwind", 14) == 0)
@@ -290,11 +320,23 @@ int module_frob_arch_sections(CONST Elf_Ehdr *hdr,
                  */
                 gots += count_gots(rels, nrels);
                 fdescs += count_fdescs(rels, nrels);
-                if(strncmp(secstrings + sechdrs[i].sh_name,
-                           ".rela.init", 10) == 0)
-                        init_stubs += count_stubs(rels, nrels);
-                else
-                        stubs += count_stubs(rels, nrels);
+
+                /* XXX: By sorting the relocs and finding duplicate entries
+                 *  we could reduce the number of necessary stubs and save
+                 *  some memory. */
+                count = count_stubs(rels, nrels);
+                if (!count)
+                        continue;
+
+                /* so we need relocation stubs. reserve necessary memory. */
+                /* sh_info gives the section for which we need to add stubs. */
+                s = sechdrs[i].sh_info;
+
+                /* each code section should only have one relocation section */
+                WARN_ON(me->arch.section[s].stub_entries);
+
+                /* store number of stubs we need for this section */
+                me->arch.section[s].stub_entries += count;
         }
 
         /* align things a bit */
@@ -306,18 +348,8 @@ int module_frob_arch_sections(CONST Elf_Ehdr *hdr,
         me->arch.fdesc_offset = me->core_size;
         me->core_size += fdescs * sizeof(Elf_Fdesc);
 
-        me->core_size = ALIGN(me->core_size, 16);
-        me->arch.stub_offset = me->core_size;
-        me->core_size += stubs * sizeof(struct stub_entry);
-
-        me->init_size = ALIGN(me->init_size, 16);
-        me->arch.init_stub_offset = me->init_size;
-        me->init_size += init_stubs * sizeof(struct stub_entry);
-
         me->arch.got_max = gots;
         me->arch.fdesc_max = fdescs;
-        me->arch.stub_max = stubs;
-        me->arch.init_stub_max = init_stubs;
 
         return 0;
 }
@@ -380,23 +412,27 @@ enum elf_stub_type {
 };
 
 static Elf_Addr get_stub(struct module *me, unsigned long value, long addend,
-        enum elf_stub_type stub_type, int init_section)
+        enum elf_stub_type stub_type, Elf_Addr loc0, unsigned int targetsec)
 {
-        unsigned long i;
         struct stub_entry *stub;
 
-        if(init_section) {
-                i = me->arch.init_stub_count++;
-                BUG_ON(me->arch.init_stub_count > me->arch.init_stub_max);
-                stub = me->module_init + me->arch.init_stub_offset + 
-                        i * sizeof(struct stub_entry);
-        } else {
-                i = me->arch.stub_count++;
-                BUG_ON(me->arch.stub_count > me->arch.stub_max);
-                stub = me->module_core + me->arch.stub_offset + 
-                        i * sizeof(struct stub_entry);
+        /* initialize stub_offset to point in front of the section */
+        if (!me->arch.section[targetsec].stub_offset) {
+                loc0 -= (me->arch.section[targetsec].stub_entries + 1) *
+                                sizeof(struct stub_entry);
+                /* get correct alignment for the stubs */
+                loc0 = ALIGN(loc0, sizeof(struct stub_entry));
+                me->arch.section[targetsec].stub_offset = loc0;
         }
 
+        /* get address of stub entry */
+        stub = (void *) me->arch.section[targetsec].stub_offset;
+        me->arch.section[targetsec].stub_offset += sizeof(struct stub_entry);
+
+        /* do not write outside available stub area */
+        BUG_ON(0 == me->arch.section[targetsec].stub_entries--);
+
+
 #ifndef CONFIG_64BIT
 /* for 32-bit the stub looks like this:
  *      ldil L'XXX,%r1
@@ -489,15 +525,19 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
         Elf32_Addr val;
         Elf32_Sword addend;
         Elf32_Addr dot;
+        Elf_Addr loc0;
+        unsigned int targetsec = sechdrs[relsec].sh_info;
         //unsigned long dp = (unsigned long)$global$;
         register unsigned long dp asm ("r27");
 
         DEBUGP("Applying relocate section %u to %u\n", relsec,
-               sechdrs[relsec].sh_info);
+               targetsec);
         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
                 /* This is where to make the change */
-                loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+                loc = (void *)sechdrs[targetsec].sh_addr
                       + rel[i].r_offset;
+                /* This is the start of the target section */
+                loc0 = sechdrs[targetsec].sh_addr;
                 /* This is the symbol it is referring to */
                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
                         + ELF32_R_SYM(rel[i].r_info);
@@ -569,19 +609,32 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
                         break;
                 case R_PARISC_PCREL17F:
                         /* 17-bit PC relative address */
-                        val = get_stub(me, val, addend, ELF_STUB_GOT, in_init(me, loc));
+                        /* calculate direct call offset */
+                        val += addend;
                         val = (val - dot - 8)/4;
-                        CHECK_RELOC(val, 17)
+                        if (!RELOC_REACHABLE(val, 17)) {
+                                /* direct distance too far, create
+                                 * stub entry instead */
+                                val = get_stub(me, sym->st_value, addend,
+                                        ELF_STUB_DIRECT, loc0, targetsec);
+                                val = (val - dot - 8)/4;
+                                CHECK_RELOC(val, 17);
+                        }
                         *loc = (*loc & ~0x1f1ffd) | reassemble_17(val);
                         break;
                 case R_PARISC_PCREL22F:
                         /* 22-bit PC relative address; only defined for pa20 */
-                        val = get_stub(me, val, addend, ELF_STUB_GOT, in_init(me, loc));
-                        DEBUGP("STUB FOR %s loc %lx+%lx at %lx\n", 
-                               strtab + sym->st_name, (unsigned long)loc, addend, 
-                               val)
+                        /* calculate direct call offset */
+                        val += addend;
                         val = (val - dot - 8)/4;
-                        CHECK_RELOC(val, 22);
+                        if (!RELOC_REACHABLE(val, 22)) {
+                                /* direct distance too far, create
+                                 * stub entry instead */
+                                val = get_stub(me, sym->st_value, addend,
+                                        ELF_STUB_DIRECT, loc0, targetsec);
+                                val = (val - dot - 8)/4;
+                                CHECK_RELOC(val, 22);
+                        }
                         *loc = (*loc & ~0x3ff1ffd) | reassemble_22(val);
                         break;
 
@@ -610,13 +663,17 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
         Elf64_Addr val;
         Elf64_Sxword addend;
         Elf64_Addr dot;
+        Elf_Addr loc0;
+        unsigned int targetsec = sechdrs[relsec].sh_info;
 
         DEBUGP("Applying relocate section %u to %u\n", relsec,
-               sechdrs[relsec].sh_info);
+               targetsec);
         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
                 /* This is where to make the change */
-                loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+                loc = (void *)sechdrs[targetsec].sh_addr
                       + rel[i].r_offset;
+                /* This is the start of the target section */
+                loc0 = sechdrs[targetsec].sh_addr;
                 /* This is the symbol it is referring to */
                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
                         + ELF64_R_SYM(rel[i].r_info);
@@ -672,42 +729,40 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
                         DEBUGP("PCREL22F Symbol %s loc %p val %lx\n",
                                strtab + sym->st_name,
                                loc, val);
+                        val += addend;
                         /* can we reach it locally? */
-                        if(!in_local_section(me, (void *)val, (void *)dot)) {
-
-                                if (in_local(me, (void *)val))
-                                        /* this is the case where the
-                                         * symbol is local to the
-                                         * module, but in a different
-                                         * section, so stub the jump
-                                         * in case it's more than 22
-                                         * bits away */
-                                        val = get_stub(me, val, addend, ELF_STUB_DIRECT,
-                                                       in_init(me, loc));
-                                else if (strncmp(strtab + sym->st_name, "$$", 2)
+                        if (in_local(me, (void *)val)) {
+                                /* this is the case where the symbol is local
+                                 * to the module, but in a different section,
+                                 * so stub the jump in case it's more than 22
+                                 * bits away */
+                                val = (val - dot - 8)/4;
+                                if (!RELOC_REACHABLE(val, 22)) {
+                                        /* direct distance too far, create
+                                         * stub entry instead */
+                                        val = get_stub(me, sym->st_value,
+                                                addend, ELF_STUB_DIRECT,
+                                                loc0, targetsec);
+                                } else {
+                                        /* Ok, we can reach it directly. */
+                                        val = sym->st_value;
+                                        val += addend;
+                                }
+                        } else {
+                                val = sym->st_value;
+                                if (strncmp(strtab + sym->st_name, "$$", 2)
                                     == 0)
                                         val = get_stub(me, val, addend, ELF_STUB_MILLI,
-                                                       in_init(me, loc));
+                                                       loc0, targetsec);
                                 else
                                         val = get_stub(me, val, addend, ELF_STUB_GOT,
-                                                       in_init(me, loc));
+                                                       loc0, targetsec);
                         }
                         DEBUGP("STUB FOR %s loc %lx, val %lx+%lx at %lx\n", 
                                strtab + sym->st_name, loc, sym->st_value,
                                addend, val);
-                        /* FIXME: local symbols work as long as the
-                         * core and init pieces aren't separated too
-                         * far.  If this is ever broken, you will trip
-                         * the check below.  The way to fix it would
-                         * be to generate local stubs to go between init
-                         * and core */
-                        if((Elf64_Sxword)(val - dot - 8) > 0x800000 -1 ||
-                           (Elf64_Sxword)(val - dot - 8) < -0x800000) {
-                                printk(KERN_ERR "Module %s, symbol %s is out of range for PCREL22F relocation\n",
-                                       me->name, strtab + sym->st_name);
-                                return -ENOEXEC;
-                        }
                         val = (val - dot - 8)/4;
+                        CHECK_RELOC(val, 22);
                         *loc = (*loc & ~0x3ff1ffd) | reassemble_22(val);
                         break;
                 case R_PARISC_DIR64:
@@ -794,12 +849,8 @@ int module_finalize(const Elf_Ehdr *hdr,
         addr = (u32 *)entry->addr;
         printk("INSNS: %x %x %x %x\n",
                addr[0], addr[1], addr[2], addr[3]);
-        printk("stubs used %ld, stubs max %ld\n"
-               "init_stubs used %ld, init stubs max %ld\n"
-               "got entries used %ld, gots max %ld\n"
+        printk("got entries used %ld, gots max %ld\n"
                "fdescs used %ld, fdescs max %ld\n",
-               me->arch.stub_count, me->arch.stub_max,
-               me->arch.init_stub_count, me->arch.init_stub_max,
                me->arch.got_count, me->arch.got_max,
                me->arch.fdesc_count, me->arch.fdesc_max);
 #endif
@@ -829,7 +880,10 @@ int module_finalize(const Elf_Ehdr *hdr,
                                 me->name, me->arch.got_count, MAX_GOTS);
                 return -EINVAL;
         }
-        
+
+        kfree(me->arch.section);
+        me->arch.section = NULL;
+
         /* no symbol table */
         if(symhdr == NULL)
                 return 0;