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-rw-r--r--arch/x86/vdso/Makefile16
-rw-r--r--arch/x86/vdso/vdso-fakesections.c21
-rw-r--r--arch/x86/vdso/vdso2c.c116
-rw-r--r--arch/x86/vdso/vdso2c.h202
4 files changed, 126 insertions, 229 deletions
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 61b04fe36e66..5a4affe025e8 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -10,7 +10,7 @@ VDSO32-$(CONFIG_X86_32) := y
VDSO32-$(CONFIG_COMPAT) := y
# files to link into the vdso
-vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vdso-fakesections.o
+vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
# files to link into kernel
obj-y += vma.o
@@ -37,7 +37,8 @@ vdso_img_sodbg := $(vdso_img-y:%=vdso%.so.dbg)
obj-y += $(vdso_img_objs)
targets += $(vdso_img_cfiles)
targets += $(vdso_img_sodbg)
-.SECONDARY: $(vdso_img-y:%=$(obj)/vdso-image-%.c)
+.SECONDARY: $(vdso_img-y:%=$(obj)/vdso-image-%.c) \
+ $(vdso_img-y:%=$(obj)/vdso%.so)
export CPPFLAGS_vdso.lds += -P -C
@@ -54,10 +55,10 @@ hostprogs-y += vdso2c
quiet_cmd_vdso2c = VDSO2C $@
define cmd_vdso2c
- $(obj)/vdso2c $< $@
+ $(obj)/vdso2c $< $(<:%.dbg=%) $@
endef
-$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso2c FORCE
+$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
$(call if_changed,vdso2c)
#
@@ -113,6 +114,10 @@ $(obj)/%-x32.o: $(obj)/%.o FORCE
targets += vdsox32.lds $(vobjx32s-y)
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg
+ $(call if_changed,objcopy)
+
$(obj)/vdsox32.so.dbg: $(src)/vdsox32.lds $(vobjx32s) FORCE
$(call if_changed,vdso)
@@ -134,7 +139,7 @@ override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
targets += vdso32/vdso32.lds
targets += vdso32/note.o vdso32/vclock_gettime.o $(vdso32.so-y:%=vdso32/%.o)
-targets += vdso32/vclock_gettime.o vdso32/vdso-fakesections.o
+targets += vdso32/vclock_gettime.o
$(obj)/vdso32.o: $(vdso32-images:%=$(obj)/%)
@@ -156,7 +161,6 @@ $(vdso32-images:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
$(vdso32-images:%=$(obj)/%.dbg): $(obj)/vdso32-%.so.dbg: FORCE \
$(obj)/vdso32/vdso32.lds \
$(obj)/vdso32/vclock_gettime.o \
- $(obj)/vdso32/vdso-fakesections.o \
$(obj)/vdso32/note.o \
$(obj)/vdso32/%.o
$(call if_changed,vdso)
diff --git a/arch/x86/vdso/vdso-fakesections.c b/arch/x86/vdso/vdso-fakesections.c
deleted file mode 100644
index aa5fbfab20a5..000000000000
--- a/arch/x86/vdso/vdso-fakesections.c
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
- * Copyright 2014 Andy Lutomirski
- * Subject to the GNU Public License, v.2
- *
- * String table for loadable section headers. See vdso2c.h for why
- * this exists.
- */
-
-const char fake_shstrtab[] __attribute__((section(".fake_shstrtab"))) =
- ".hash\0"
- ".dynsym\0"
- ".dynstr\0"
- ".gnu.version\0"
- ".gnu.version_d\0"
- ".dynamic\0"
- ".rodata\0"
- ".fake_shstrtab\0" /* Yay, self-referential code. */
- ".note\0"
- ".eh_frame_hdr\0"
- ".eh_frame\0"
- ".text";
diff --git a/arch/x86/vdso/vdso2c.c b/arch/x86/vdso/vdso2c.c
index 22c54d04bced..8627db24a7f6 100644
--- a/arch/x86/vdso/vdso2c.c
+++ b/arch/x86/vdso/vdso2c.c
@@ -1,3 +1,53 @@
+/*
+ * vdso2c - A vdso image preparation tool
+ * Copyright (c) 2014 Andy Lutomirski and others
+ * Licensed under the GPL v2
+ *
+ * vdso2c requires stripped and unstripped input. It would be trivial
+ * to fully strip the input in here, but, for reasons described below,
+ * we need to write a section table. Doing this is more or less
+ * equivalent to dropping all non-allocatable sections, but it's
+ * easier to let objcopy handle that instead of doing it ourselves.
+ * If we ever need to do something fancier than what objcopy provides,
+ * it would be straightforward to add here.
+ *
+ * We're keep a section table for a few reasons:
+ *
+ * The Go runtime had a couple of bugs: it would read the section
+ * table to try to figure out how many dynamic symbols there were (it
+ * shouldn't have looked at the section table at all) and, if there
+ * were no SHT_SYNDYM section table entry, it would use an
+ * uninitialized value for the number of symbols. An empty DYNSYM
+ * table would work, but I see no reason not to write a valid one (and
+ * keep full performance for old Go programs). This hack is only
+ * needed on x86_64.
+ *
+ * The bug was introduced on 2012-08-31 by:
+ * https://code.google.com/p/go/source/detail?r=56ea40aac72b
+ * and was fixed on 2014-06-13 by:
+ * https://code.google.com/p/go/source/detail?r=fc1cd5e12595
+ *
+ * Binutils has issues debugging the vDSO: it reads the section table to
+ * find SHT_NOTE; it won't look at PT_NOTE for the in-memory vDSO, which
+ * would break build-id if we removed the section table. Binutils
+ * also requires that shstrndx != 0. See:
+ * https://sourceware.org/bugzilla/show_bug.cgi?id=17064
+ *
+ * elfutils might not look for PT_NOTE if there is a section table at
+ * all. I don't know whether this matters for any practical purpose.
+ *
+ * For simplicity, rather than hacking up a partial section table, we
+ * just write a mostly complete one. We omit non-dynamic symbols,
+ * though, since they're rather large.
+ *
+ * Once binutils gets fixed, we might be able to drop this for all but
+ * the 64-bit vdso, since build-id only works in kernel RPMs, and
+ * systems that update to new enough kernel RPMs will likely update
+ * binutils in sync. build-id has never worked for home-built kernel
+ * RPMs without manual symlinking, and I suspect that no one ever does
+ * that.
+ */
+
#include <inttypes.h>
#include <stdint.h>
#include <unistd.h>
@@ -61,7 +111,8 @@ static void fail(const char *format, ...)
va_start(ap, format);
fprintf(stderr, "Error: ");
vfprintf(stderr, format, ap);
- unlink(outfilename);
+ if (outfilename)
+ unlink(outfilename);
exit(1);
va_end(ap);
}
@@ -114,30 +165,53 @@ extern void bad_put_le(void);
#include "vdso2c.h"
#undef ELF_BITS
-static void go(void *addr, size_t len, FILE *outfile, const char *name)
+static void go(void *raw_addr, size_t raw_len,
+ void *stripped_addr, size_t stripped_len,
+ FILE *outfile, const char *name)
{
- Elf64_Ehdr *hdr = (Elf64_Ehdr *)addr;
+ Elf64_Ehdr *hdr = (Elf64_Ehdr *)raw_addr;
if (hdr->e_ident[EI_CLASS] == ELFCLASS64) {
- go64(addr, len, outfile, name);
+ go64(raw_addr, raw_len, stripped_addr, stripped_len,
+ outfile, name);
} else if (hdr->e_ident[EI_CLASS] == ELFCLASS32) {
- go32(addr, len, outfile, name);
+ go32(raw_addr, raw_len, stripped_addr, stripped_len,
+ outfile, name);
} else {
fail("unknown ELF class\n");
}
}
+static void map_input(const char *name, void **addr, size_t *len, int prot)
+{
+ off_t tmp_len;
+
+ int fd = open(name, O_RDONLY);
+ if (fd == -1)
+ err(1, "%s", name);
+
+ tmp_len = lseek(fd, 0, SEEK_END);
+ if (tmp_len == (off_t)-1)
+ err(1, "lseek");
+ *len = (size_t)tmp_len;
+
+ *addr = mmap(NULL, tmp_len, prot, MAP_PRIVATE, fd, 0);
+ if (*addr == MAP_FAILED)
+ err(1, "mmap");
+
+ close(fd);
+}
+
int main(int argc, char **argv)
{
- int fd;
- off_t len;
- void *addr;
+ size_t raw_len, stripped_len;
+ void *raw_addr, *stripped_addr;
FILE *outfile;
char *name, *tmp;
int namelen;
- if (argc != 3) {
- printf("Usage: vdso2c INPUT OUTPUT\n");
+ if (argc != 4) {
+ printf("Usage: vdso2c RAW_INPUT STRIPPED_INPUT OUTPUT\n");
return 1;
}
@@ -145,7 +219,7 @@ int main(int argc, char **argv)
* Figure out the struct name. If we're writing to a .so file,
* generate raw output insted.
*/
- name = strdup(argv[2]);
+ name = strdup(argv[3]);
namelen = strlen(name);
if (namelen >= 3 && !strcmp(name + namelen - 3, ".so")) {
name = NULL;
@@ -161,26 +235,18 @@ int main(int argc, char **argv)
*tmp = '_';
}
- fd = open(argv[1], O_RDONLY);
- if (fd == -1)
- err(1, "%s", argv[1]);
-
- len = lseek(fd, 0, SEEK_END);
- if (len == (off_t)-1)
- err(1, "lseek");
-
- addr = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
- if (addr == MAP_FAILED)
- err(1, "mmap");
+ map_input(argv[1], &raw_addr, &raw_len, PROT_READ);
+ map_input(argv[2], &stripped_addr, &stripped_len, PROT_READ);
- outfilename = argv[2];
+ outfilename = argv[3];
outfile = fopen(outfilename, "w");
if (!outfile)
err(1, "%s", argv[2]);
- go(addr, (size_t)len, outfile, name);
+ go(raw_addr, raw_len, stripped_addr, stripped_len, outfile, name);
- munmap(addr, len);
+ munmap(raw_addr, raw_len);
+ munmap(stripped_addr, stripped_len);
fclose(outfile);
return 0;
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index 2da32fbc46da..fd57829b30d8 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -4,128 +4,14 @@
* are built for 32-bit userspace.
*/
-/*
- * We're writing a section table for a few reasons:
- *
- * The Go runtime had a couple of bugs: it would read the section
- * table to try to figure out how many dynamic symbols there were (it
- * shouldn't have looked at the section table at all) and, if there
- * were no SHT_SYNDYM section table entry, it would use an
- * uninitialized value for the number of symbols. An empty DYNSYM
- * table would work, but I see no reason not to write a valid one (and
- * keep full performance for old Go programs). This hack is only
- * needed on x86_64.
- *
- * The bug was introduced on 2012-08-31 by:
- * https://code.google.com/p/go/source/detail?r=56ea40aac72b
- * and was fixed on 2014-06-13 by:
- * https://code.google.com/p/go/source/detail?r=fc1cd5e12595
- *
- * Binutils has issues debugging the vDSO: it reads the section table to
- * find SHT_NOTE; it won't look at PT_NOTE for the in-memory vDSO, which
- * would break build-id if we removed the section table. Binutils
- * also requires that shstrndx != 0. See:
- * https://sourceware.org/bugzilla/show_bug.cgi?id=17064
- *
- * elfutils might not look for PT_NOTE if there is a section table at
- * all. I don't know whether this matters for any practical purpose.
- *
- * For simplicity, rather than hacking up a partial section table, we
- * just write a mostly complete one. We omit non-dynamic symbols,
- * though, since they're rather large.
- *
- * Once binutils gets fixed, we might be able to drop this for all but
- * the 64-bit vdso, since build-id only works in kernel RPMs, and
- * systems that update to new enough kernel RPMs will likely update
- * binutils in sync. build-id has never worked for home-built kernel
- * RPMs without manual symlinking, and I suspect that no one ever does
- * that.
- */
-struct BITSFUNC(fake_sections)
-{
- ELF(Shdr) *table;
- unsigned long table_offset;
- int count, max_count;
-
- int in_shstrndx;
- unsigned long shstr_offset;
- const char *shstrtab;
- size_t shstrtab_len;
-
- int out_shstrndx;
-};
-
-static unsigned int BITSFUNC(find_shname)(struct BITSFUNC(fake_sections) *out,
- const char *name)
-{
- const char *outname = out->shstrtab;
- while (outname - out->shstrtab < out->shstrtab_len) {
- if (!strcmp(name, outname))
- return (outname - out->shstrtab) + out->shstr_offset;
- outname += strlen(outname) + 1;
- }
-
- if (*name)
- printf("Warning: could not find output name \"%s\"\n", name);
- return out->shstr_offset + out->shstrtab_len - 1; /* Use a null. */
-}
-
-static void BITSFUNC(init_sections)(struct BITSFUNC(fake_sections) *out)
-{
- if (!out->in_shstrndx)
- fail("didn't find the fake shstrndx\n");
-
- memset(out->table, 0, out->max_count * sizeof(ELF(Shdr)));
-
- if (out->max_count < 1)
- fail("we need at least two fake output sections\n");
-
- PUT_LE(&out->table[0].sh_type, SHT_NULL);
- PUT_LE(&out->table[0].sh_name, BITSFUNC(find_shname)(out, ""));
-
- out->count = 1;
-}
-
-static void BITSFUNC(copy_section)(struct BITSFUNC(fake_sections) *out,
- int in_idx, const ELF(Shdr) *in,
- const char *name)
-{
- uint64_t flags = GET_LE(&in->sh_flags);
-
- bool copy = flags & SHF_ALLOC &&
- (GET_LE(&in->sh_size) ||
- (GET_LE(&in->sh_type) != SHT_RELA &&
- GET_LE(&in->sh_type) != SHT_REL)) &&
- strcmp(name, ".altinstructions") &&
- strcmp(name, ".altinstr_replacement");
-
- if (!copy)
- return;
-
- if (out->count >= out->max_count)
- fail("too many copied sections (max = %d)\n", out->max_count);
-
- if (in_idx == out->in_shstrndx)
- out->out_shstrndx = out->count;
-
- out->table[out->count] = *in;
- PUT_LE(&out->table[out->count].sh_name,
- BITSFUNC(find_shname)(out, name));
-
- /* elfutils requires that a strtab have the correct type. */
- if (!strcmp(name, ".fake_shstrtab"))
- PUT_LE(&out->table[out->count].sh_type, SHT_STRTAB);
-
- out->count++;
-}
-
-static void BITSFUNC(go)(void *addr, size_t len,
+static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
+ void *stripped_addr, size_t stripped_len,
FILE *outfile, const char *name)
{
int found_load = 0;
unsigned long load_size = -1; /* Work around bogus warning */
- unsigned long data_size;
- ELF(Ehdr) *hdr = (ELF(Ehdr) *)addr;
+ unsigned long mapping_size;
+ ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
int i;
unsigned long j;
ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
@@ -134,9 +20,7 @@ static void BITSFUNC(go)(void *addr, size_t len,
const char *secstrings;
INT_BITS syms[NSYMS] = {};
- struct BITSFUNC(fake_sections) fake_sections = {};
-
- ELF(Phdr) *pt = (ELF(Phdr) *)(addr + GET_LE(&hdr->e_phoff));
+ ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff));
/* Walk the segment table. */
for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
@@ -154,14 +38,16 @@ static void BITSFUNC(go)(void *addr, size_t len,
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) +
+ dyn = raw_addr + GET_LE(&pt[i].p_offset);
+ dyn_end = raw_addr + GET_LE(&pt[i].p_offset) +
GET_LE(&pt[i].p_memsz);
}
}
if (!found_load)
fail("no PT_LOAD seg\n");
- data_size = (load_size + 4095) / 4096 * 4096;
+
+ if (stripped_len < load_size)
+ fail("stripped input is too short\n");
/* Walk the dynamic table */
for (i = 0; dyn + i < dyn_end &&
@@ -173,11 +59,11 @@ static void BITSFUNC(go)(void *addr, size_t len,
}
/* Walk the section table */
- secstrings_hdr = addr + GET_LE(&hdr->e_shoff) +
+ secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
- secstrings = addr + GET_LE(&secstrings_hdr->sh_offset);
+ secstrings = raw_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) +
+ ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * i;
if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
symtab_hdr = sh;
@@ -190,7 +76,7 @@ static void BITSFUNC(go)(void *addr, size_t len,
if (!symtab_hdr)
fail("no symbol table\n");
- strtab_hdr = addr + GET_LE(&hdr->e_shoff) +
+ strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) +
GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link);
/* Walk the symbol table */
@@ -198,9 +84,9 @@ static void BITSFUNC(go)(void *addr, size_t len,
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) +
+ ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) +
GET_LE(&symtab_hdr->sh_entsize) * i;
- const char *name = addr + GET_LE(&strtab_hdr->sh_offset) +
+ const char *name = raw_addr + GET_LE(&strtab_hdr->sh_offset) +
GET_LE(&sym->st_name);
for (k = 0; k < NSYMS; k++) {
@@ -219,48 +105,7 @@ static void BITSFUNC(go)(void *addr, size_t len,
syms[k] = GET_LE(&sym->st_value);
}
}
-
- if (!strcmp(name, "fake_shstrtab")) {
- ELF(Shdr) *sh;
-
- fake_sections.in_shstrndx = GET_LE(&sym->st_shndx);
- fake_sections.shstrtab = addr + GET_LE(&sym->st_value);
- fake_sections.shstrtab_len = GET_LE(&sym->st_size);
- sh = addr + GET_LE(&hdr->e_shoff) +
- GET_LE(&hdr->e_shentsize) *
- fake_sections.in_shstrndx;
- fake_sections.shstr_offset = GET_LE(&sym->st_value) -
- GET_LE(&sh->sh_addr);
- }
- }
-
- /* Build the output section table. */
- if (!syms[sym_VDSO_FAKE_SECTION_TABLE_START] ||
- !syms[sym_VDSO_FAKE_SECTION_TABLE_END])
- fail("couldn't find fake section table\n");
- if ((syms[sym_VDSO_FAKE_SECTION_TABLE_END] -
- syms[sym_VDSO_FAKE_SECTION_TABLE_START]) % sizeof(ELF(Shdr)))
- fail("fake section table size isn't a multiple of sizeof(Shdr)\n");
- fake_sections.table = addr + syms[sym_VDSO_FAKE_SECTION_TABLE_START];
- fake_sections.table_offset = syms[sym_VDSO_FAKE_SECTION_TABLE_START];
- fake_sections.max_count = (syms[sym_VDSO_FAKE_SECTION_TABLE_END] -
- syms[sym_VDSO_FAKE_SECTION_TABLE_START]) /
- sizeof(ELF(Shdr));
-
- BITSFUNC(init_sections)(&fake_sections);
- 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;
- BITSFUNC(copy_section)(&fake_sections, i, sh,
- secstrings + GET_LE(&sh->sh_name));
}
- if (!fake_sections.out_shstrndx)
- fail("didn't generate shstrndx?!?\n");
-
- PUT_LE(&hdr->e_shoff, fake_sections.table_offset);
- PUT_LE(&hdr->e_shentsize, sizeof(ELF(Shdr)));
- PUT_LE(&hdr->e_shnum, fake_sections.count);
- PUT_LE(&hdr->e_shstrndx, fake_sections.out_shstrndx);
/* Validate mapping addresses. */
for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
@@ -281,10 +126,12 @@ static void BITSFUNC(go)(void *addr, size_t len,
fail("vvar_begin must be a multiple of 4096\n");
if (!name) {
- fwrite(addr, load_size, 1, outfile);
+ fwrite(stripped_addr, stripped_len, 1, outfile);
return;
}
+ mapping_size = (stripped_len + 4095) / 4096 * 4096;
+
fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
fprintf(outfile, "#include <linux/linkage.h>\n");
fprintf(outfile, "#include <asm/page_types.h>\n");
@@ -292,20 +139,21 @@ static void BITSFUNC(go)(void *addr, size_t len,
fprintf(outfile, "\n");
fprintf(outfile,
"static unsigned char raw_data[%lu] __page_aligned_data = {",
- data_size);
- for (j = 0; j < load_size; j++) {
+ mapping_size);
+ for (j = 0; j < stripped_len; j++) {
if (j % 10 == 0)
fprintf(outfile, "\n\t");
- fprintf(outfile, "0x%02X, ", (int)((unsigned char *)addr)[j]);
+ fprintf(outfile, "0x%02X, ",
+ (int)((unsigned char *)stripped_addr)[j]);
}
fprintf(outfile, "\n};\n\n");
fprintf(outfile, "static struct page *pages[%lu];\n\n",
- data_size / 4096);
+ mapping_size / 4096);
fprintf(outfile, "const struct vdso_image %s = {\n", name);
fprintf(outfile, "\t.data = raw_data,\n");
- fprintf(outfile, "\t.size = %lu,\n", data_size);
+ fprintf(outfile, "\t.size = %lu,\n", mapping_size);
fprintf(outfile, "\t.text_mapping = {\n");
fprintf(outfile, "\t\t.name = \"[vdso]\",\n");
fprintf(outfile, "\t\t.pages = pages,\n");
generated by cgit v1.2.3 (git 2.0.4) at 2024-09-24 18:26:02 +0000