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x86, vdso: Use <tools/le_byteshift.h> for littleendian access
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There are no standard functions for littleendian data (unlike
bigendian data.)  Thus, use <tools/le_byteshift.h> to access
littleendian data members.  Those are fairly inefficient, but it
doesn't matter for this purpose (and can be optimized later.)  This
avoids portability problems.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/20140606140017.afb7f91142f66cb3dd13c186@linux-foundation.org
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H. Peter Anvin committed Jun 6, 2014
1 parent a0abcf2 commit bdfb9bc
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Showing 3 changed files with 38 additions and 35 deletions.
1 change: 1 addition & 0 deletions arch/x86/vdso/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ VDSO_LDFLAGS_vdso.lds = -m64 -Wl,-soname=linux-vdso.so.1 \
$(obj)/vdso64.so.dbg: $(src)/vdso.lds $(vobjs) FORCE
$(call if_changed,vdso)

HOST_EXTRACFLAGS += -I$(srctree)/tools/include
hostprogs-y += vdso2c

quiet_cmd_vdso2c = VDSO2C $@
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10 changes: 6 additions & 4 deletions arch/x86/vdso/vdso2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@
#include <sys/mman.h>
#include <sys/types.h>

#include <tools/le_byteshift.h>

#include <linux/elf.h>
#include <linux/types.h>

Expand Down Expand Up @@ -56,12 +58,12 @@ static void fail(const char *format, ...)
*/
#define GLE(x, bits, ifnot) \
__builtin_choose_expr( \
(sizeof(x) == bits/8), \
(__typeof__(x))le##bits##toh(x), ifnot)
(sizeof(*(x)) == bits/8), \
(__typeof__(*(x)))get_unaligned_le##bits(x), ifnot)

extern void bad_get_le(uint64_t);
extern void bad_get_le(void);
#define LAST_LE(x) \
__builtin_choose_expr(sizeof(x) == 1, (x), bad_get_le(x))
__builtin_choose_expr(sizeof(*(x)) == 1, *(x), bad_get_le())

#define GET_LE(x) \
GLE(x, 64, GLE(x, 32, GLE(x, 16, LAST_LE(x))))
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62 changes: 31 additions & 31 deletions arch/x86/vdso/vdso2c.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,27 +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 + GET_LE(hdr->e_phoff));
Elf_Phdr *pt = (Elf_Phdr *)(addr + GET_LE(&hdr->e_phoff));

/* Walk the segment table. */
for (i = 0; i < GET_LE(hdr->e_phnum); i++) {
if (GET_LE(pt[i].p_type) == PT_LOAD) {
for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
if (GET_LE(&pt[i].p_type) == PT_LOAD) {
if (found_load)
fail("multiple PT_LOAD segs\n");

if (GET_LE(pt[i].p_offset) != 0 ||
GET_LE(pt[i].p_vaddr) != 0)
if (GET_LE(&pt[i].p_offset) != 0 ||
GET_LE(&pt[i].p_vaddr) != 0)
fail("PT_LOAD in wrong place\n");

if (GET_LE(pt[i].p_memsz) != GET_LE(pt[i].p_filesz))
if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz))
fail("cannot handle memsz != filesz\n");

load_size = GET_LE(pt[i].p_memsz);
load_size = GET_LE(&pt[i].p_memsz);
found_load = 1;
} else if (GET_LE(pt[i].p_type) == PT_DYNAMIC) {
dyn = addr + GET_LE(pt[i].p_offset);
dyn_end = addr + GET_LE(pt[i].p_offset) +
GET_LE(pt[i].p_memsz);
} else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) {
dyn = addr + GET_LE(&pt[i].p_offset);
dyn_end = addr + GET_LE(&pt[i].p_offset) +
GET_LE(&pt[i].p_memsz);
}
}
if (!found_load)
Expand All @@ -47,50 +47,50 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)

/* Walk the dynamic table */
for (i = 0; dyn + i < dyn_end &&
GET_LE(dyn[i].d_tag) != DT_NULL; i++) {
typeof(dyn[i].d_tag) tag = GET_LE(dyn[i].d_tag);
GET_LE(&dyn[i].d_tag) != DT_NULL; i++) {
typeof(dyn[i].d_tag) tag = GET_LE(&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 + GET_LE(hdr->e_shoff) +
GET_LE(hdr->e_shentsize)*GET_LE(hdr->e_shstrndx);
secstrings = addr + GET_LE(secstrings_hdr->sh_offset);
for (i = 0; i < GET_LE(hdr->e_shnum); i++) {
Elf_Shdr *sh = addr + GET_LE(hdr->e_shoff) +
GET_LE(hdr->e_shentsize) * i;
if (GET_LE(sh->sh_type) == SHT_SYMTAB)
secstrings_hdr = addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
secstrings = addr + GET_LE(&secstrings_hdr->sh_offset);
for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
Elf_Shdr *sh = addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * i;
if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
symtab_hdr = sh;

if (!strcmp(secstrings + GET_LE(sh->sh_name),
if (!strcmp(secstrings + GET_LE(&sh->sh_name),
".altinstructions"))
alt_sec = sh;
}

if (!symtab_hdr)
fail("no symbol table\n");

strtab_hdr = addr + GET_LE(hdr->e_shoff) +
GET_LE(hdr->e_shentsize) * GET_LE(symtab_hdr->sh_link);
strtab_hdr = addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);

/* Walk the symbol table */
for (i = 0;
i < GET_LE(symtab_hdr->sh_size) / GET_LE(symtab_hdr->sh_entsize);
i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
i++) {
int k;
Elf_Sym *sym = addr + GET_LE(symtab_hdr->sh_offset) +
GET_LE(symtab_hdr->sh_entsize) * i;
const char *name = addr + GET_LE(strtab_hdr->sh_offset) +
GET_LE(sym->st_name);
Elf_Sym *sym = addr + GET_LE(&symtab_hdr->sh_offset) +
GET_LE(&symtab_hdr->sh_entsize) * i;
const char *name = addr + GET_LE(&strtab_hdr->sh_offset) +
GET_LE(&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] = GET_LE(sym->st_value);
syms[k] = GET_LE(&sym->st_value);
}
}
}
Expand Down Expand Up @@ -150,9 +150,9 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
fprintf(outfile, "\t},\n");
if (alt_sec) {
fprintf(outfile, "\t.alt = %lu,\n",
(unsigned long)GET_LE(alt_sec->sh_offset));
(unsigned long)GET_LE(&alt_sec->sh_offset));
fprintf(outfile, "\t.alt_len = %lu,\n",
(unsigned long)GET_LE(alt_sec->sh_size));
(unsigned long)GET_LE(&alt_sec->sh_size));
}
for (i = 0; i < NSYMS; i++) {
if (syms[i])
Expand Down

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