*
* 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
*
*
* 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:
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/bug.h>
-#include <linux/uaccess.h>
-#include <asm/sections.h>
#include <asm/unwind.h>
#if 0
#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; \
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;
};
-#define Elf_Fdesc Elf32_Fdesc
-
struct stub_entry {
Elf32_Word insns[2]; /* each stub entry has two insns */
};
Elf64_Addr addr;
};
-#define Elf_Fdesc Elf64_Fdesc
-
struct stub_entry {
Elf64_Word insns[4]; /* each stub entry has four insns */
};
/* 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)
*/
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 */
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;
}
};
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
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);
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;
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);
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:
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
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;
deregister_unwind_table(mod);
module_bug_cleanup(mod);
}
-
-#ifdef CONFIG_64BIT
-void *dereference_function_descriptor(void *ptr)
-{
- Elf64_Fdesc *desc = ptr;
- void *p;
-
- if (!probe_kernel_address(&desc->addr, p))
- ptr = p;
- return ptr;
-}
-#endif
git.openpandora.org / pandora-kernel.git / blobdiff