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qemu/linux-user/flatload.c
Peter Maydell a6819c1bd0 linux-user/flatload.c: Remove unused bFLT shared-library and ZFLAT code 
Ever since the bFLT format support was added in 2006, there has been
a chunk of code in the file guarded by CONFIG_BINFMT_SHARED_FLAT
which is supposedly for shared library support.  This is not enabled
and it's not possible to enable it, because if you do you'll run into
the "#error needs checking" in the calc_reloc() function.

Similarly, CONFIG_BINFMT_ZFLAT exists but can't be enabled because of
an "#error code needs checking" in load_flat_file().

This code is obviously unfinished and has never been used; nobody in
the intervening 18 years has complained about this or fixed it, so
just delete the dead code.  If anybody ever wants the feature they
can always pull it out of git, or (perhaps better) write it from
scratch based on the current Linux bFLT loader rather than the one of
18 years ago.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20240411115313.680433-1-peter.maydell@linaro.org
2024-04-25 10:21:06 +01:00

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/****************************************************************************/
/*
* QEMU bFLT binary loader. Based on linux/fs/binfmt_flat.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*
* Copyright (C) 2006 CodeSourcery.
* Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
* Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
* Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
* Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
* based heavily on:
*
* linux/fs/binfmt_aout.c:
* Copyright (C) 1991, 1992, 1996 Linus Torvalds
* linux/fs/binfmt_flat.c for 2.0 kernel
* Copyright (C) 1998 Kenneth Albanowski <kjahds@kjahds.com>
* JAN/99 -- coded full program relocation (gerg@snapgear.com)
*/
/****************************************************************************/
#include "qemu/osdep.h"
#include "qemu.h"
#include "user-internals.h"
#include "loader.h"
#include "user-mmap.h"
#include "flat.h"
#include "target_flat.h"
//#define DEBUG
#ifdef DEBUG
#define DBG_FLT(...) printf(__VA_ARGS__)
#else
#define DBG_FLT(...)
#endif
#define RELOC_FAILED 0xff00ff01 /* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff /* Placeholder for unused library */
struct lib_info {
abi_ulong start_code; /* Start of text segment */
abi_ulong start_data; /* Start of data segment */
abi_ulong end_data; /* Start of bss section */
abi_ulong start_brk; /* End of data segment */
abi_ulong text_len; /* Length of text segment */
abi_ulong entry; /* Start address for this module */
abi_ulong build_date; /* When this one was compiled */
short loaded; /* Has this library been loaded? */
};
struct linux_binprm;
/****************************************************************************/
/*
* create_flat_tables() parses the env- and arg-strings in new user
* memory and creates the pointer tables from them, and puts their
* addresses on the "stack", returning the new stack pointer value.
*/
/* Push a block of strings onto the guest stack. */
static abi_ulong copy_strings(abi_ulong p, int n, char **s)
{
int len;
while (n-- > 0) {
len = strlen(s[n]) + 1;
p -= len;
memcpy_to_target(p, s[n], len);
}
return p;
}
static int target_pread(int fd, abi_ulong ptr, abi_ulong len,
abi_ulong offset)
{
void *buf;
int ret;
buf = lock_user(VERIFY_WRITE, ptr, len, 0);
if (!buf) {
return -EFAULT;
}
ret = pread(fd, buf, len, offset);
if (ret < 0) {
ret = -errno;
}
unlock_user(buf, ptr, len);
return ret;
}
/****************************************************************************/
static abi_ulong
calc_reloc(abi_ulong r, struct lib_info *p, int curid, int internalp)
{
abi_ulong addr;
int id;
abi_ulong start_brk;
abi_ulong start_data;
abi_ulong text_len;
abi_ulong start_code;
id = 0;
start_brk = p[id].start_brk;
start_data = p[id].start_data;
start_code = p[id].start_code;
text_len = p[id].text_len;
if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
fprintf(stderr, "BINFMT_FLAT: reloc outside program 0x%x "
"(0 - 0x%x/0x%x)\n",
(int) r,(int)(start_brk-start_code),(int)text_len);
goto failed;
}
if (r < text_len) /* In text segment */
addr = r + start_code;
else /* In data segment */
addr = r - text_len + start_data;
/* Range checked already above so doing the range tests is redundant...*/
return(addr);
failed:
abort();
return RELOC_FAILED;
}
/****************************************************************************/
/* ??? This does not handle endianness correctly. */
static void old_reloc(struct lib_info *libinfo, uint32_t rl)
{
#ifdef DEBUG
const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
#endif
uint32_t *ptr;
uint32_t offset;
int reloc_type;
offset = rl & 0x3fffffff;
reloc_type = rl >> 30;
/* ??? How to handle this? */
#if defined(CONFIG_COLDFIRE)
ptr = (uint32_t *) ((unsigned long) libinfo->start_code + offset);
#else
ptr = (uint32_t *) ((unsigned long) libinfo->start_data + offset);
#endif
#ifdef DEBUG
fprintf(stderr, "Relocation of variable at DATASEG+%x "
"(address %p, currently %x) into segment %s\n",
offset, ptr, (int)*ptr, segment[reloc_type]);
#endif
switch (reloc_type) {
case OLD_FLAT_RELOC_TYPE_TEXT:
*ptr += libinfo->start_code;
break;
case OLD_FLAT_RELOC_TYPE_DATA:
*ptr += libinfo->start_data;
break;
case OLD_FLAT_RELOC_TYPE_BSS:
*ptr += libinfo->end_data;
break;
default:
fprintf(stderr, "BINFMT_FLAT: Unknown relocation type=%x\n",
reloc_type);
break;
}
DBG_FLT("Relocation became %x\n", (int)*ptr);
}
/****************************************************************************/
static int load_flat_file(struct linux_binprm * bprm,
struct lib_info *libinfo, int id, abi_ulong *extra_stack)
{
struct flat_hdr * hdr;
abi_ulong textpos = 0, datapos = 0;
abi_long result;
abi_ulong realdatastart = 0;
abi_ulong text_len, data_len, bss_len, stack_len, flags;
abi_ulong extra;
abi_ulong reloc = 0, rp;
int i, rev, relocs = 0;
abi_ulong fpos;
abi_ulong start_code;
abi_ulong indx_len;
hdr = ((struct flat_hdr *) bprm->buf); /* exec-header */
text_len = ntohl(hdr->data_start);
data_len = ntohl(hdr->data_end) - ntohl(hdr->data_start);
bss_len = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
stack_len = ntohl(hdr->stack_size);
if (extra_stack) {
stack_len += *extra_stack;
*extra_stack = stack_len;
}
relocs = ntohl(hdr->reloc_count);
flags = ntohl(hdr->flags);
rev = ntohl(hdr->rev);
DBG_FLT("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
fprintf(stderr, "BINFMT_FLAT: bad magic/rev (0x%x, need 0x%x)\n",
rev, (int) FLAT_VERSION);
return -ENOEXEC;
}
/* Don't allow old format executables to use shared libraries */
if (rev == OLD_FLAT_VERSION && id != 0) {
fprintf(stderr, "BINFMT_FLAT: shared libraries are not available\n");
return -ENOEXEC;
}
/*
* fix up the flags for the older format, there were all kinds
* of endian hacks, this only works for the simple cases
*/
if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
flags = FLAT_FLAG_RAM;
if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
fprintf(stderr, "ZFLAT executables are not supported\n");
return -ENOEXEC;
}
/*
* calculate the extra space we need to map in
*/
extra = relocs * sizeof(abi_ulong);
if (extra < bss_len + stack_len)
extra = bss_len + stack_len;
/* Add space for library base pointers. Make sure this does not
misalign the doesn't misalign the data segment. */
indx_len = MAX_SHARED_LIBS * sizeof(abi_ulong);
indx_len = (indx_len + 15) & ~(abi_ulong)15;
/*
* Allocate the address space.
*/
probe_guest_base(bprm->filename, 0,
text_len + data_len + extra + indx_len - 1);
/*
* there are a couple of cases here, the separate code/data
* case, and then the fully copied to RAM case which lumps
* it all together.
*/
if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
/*
* this should give us a ROM ptr, but if it doesn't we don't
* really care
*/
DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
textpos = target_mmap(0, text_len, PROT_READ|PROT_EXEC,
MAP_PRIVATE, bprm->src.fd, 0);
if (textpos == -1) {
fprintf(stderr, "Unable to mmap process text\n");
return -1;
}
realdatastart = target_mmap(0, data_len + extra + indx_len,
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (realdatastart == -1) {
fprintf(stderr, "Unable to allocate RAM for process data\n");
return realdatastart;
}
datapos = realdatastart + indx_len;
DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
(int)(data_len + bss_len + stack_len), (int)datapos);
fpos = ntohl(hdr->data_start);
result = target_pread(bprm->src.fd, datapos,
data_len + (relocs * sizeof(abi_ulong)),
fpos);
if (result < 0) {
fprintf(stderr, "Unable to read data+bss\n");
return result;
}
reloc = datapos + (ntohl(hdr->reloc_start) - text_len);
} else {
textpos = target_mmap(0, text_len + data_len + extra + indx_len,
PROT_READ | PROT_EXEC | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (textpos == -1 ) {
fprintf(stderr, "Unable to allocate RAM for process text/data\n");
return -1;
}
realdatastart = textpos + ntohl(hdr->data_start);
datapos = realdatastart + indx_len;
reloc = (textpos + ntohl(hdr->reloc_start) + indx_len);
result = target_pread(bprm->src.fd, textpos,
text_len, 0);
if (result >= 0) {
result = target_pread(bprm->src.fd, datapos,
data_len + (relocs * sizeof(abi_ulong)),
ntohl(hdr->data_start));
}
if (result < 0) {
fprintf(stderr, "Unable to read code+data+bss\n");
return result;
}
}
DBG_FLT("Mapping is 0x%x, Entry point is 0x%x, data_start is 0x%x\n",
(int)textpos, 0x00ffffff&ntohl(hdr->entry),
ntohl(hdr->data_start));
/* The main program needs a little extra setup in the task structure */
start_code = textpos + sizeof (struct flat_hdr);
DBG_FLT("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
id ? "Lib" : "Load", bprm->filename,
(int) start_code, (int) (textpos + text_len),
(int) datapos,
(int) (datapos + data_len),
(int) (datapos + data_len),
(int) (((datapos + data_len + bss_len) + 3) & ~3));
text_len -= sizeof(struct flat_hdr); /* the real code len */
/* Store the current module values into the global library structure */
libinfo[id].start_code = start_code;
libinfo[id].start_data = datapos;
libinfo[id].end_data = datapos + data_len;
libinfo[id].start_brk = datapos + data_len + bss_len;
libinfo[id].text_len = text_len;
libinfo[id].loaded = 1;
libinfo[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
libinfo[id].build_date = ntohl(hdr->build_date);
/*
* We just load the allocations into some temporary memory to
* help simplify all this mumbo jumbo
*
* We've got two different sections of relocation entries.
* The first is the GOT which resides at the beginning of the data segment
* and is terminated with a -1. This one can be relocated in place.
* The second is the extra relocation entries tacked after the image's
* data segment. These require a little more processing as the entry is
* really an offset into the image which contains an offset into the
* image.
*/
if (flags & FLAT_FLAG_GOTPIC) {
rp = datapos;
while (1) {
abi_ulong addr;
if (get_user_ual(addr, rp))
return -EFAULT;
if (addr == -1)
break;
if (addr) {
addr = calc_reloc(addr, libinfo, id, 0);
if (addr == RELOC_FAILED)
return -ENOEXEC;
if (put_user_ual(addr, rp))
return -EFAULT;
}
rp += sizeof(abi_ulong);
}
}
/*
* Now run through the relocation entries.
* We've got to be careful here as C++ produces relocatable zero
* entries in the constructor and destructor tables which are then
* tested for being not zero (which will always occur unless we're
* based from address zero). This causes an endless loop as __start
* is at zero. The solution used is to not relocate zero addresses.
* This has the negative side effect of not allowing a global data
* reference to be statically initialised to _stext (I've moved
* __start to address 4 so that is okay).
*/
if (rev > OLD_FLAT_VERSION) {
abi_ulong persistent = 0;
for (i = 0; i < relocs; i++) {
abi_ulong addr, relval;
/* Get the address of the pointer to be
relocated (of course, the address has to be
relocated first). */
if (get_user_ual(relval, reloc + i * sizeof(abi_ulong)))
return -EFAULT;
relval = ntohl(relval);
if (flat_set_persistent(relval, &persistent))
continue;
addr = flat_get_relocate_addr(relval);
rp = calc_reloc(addr, libinfo, id, 1);
if (rp == RELOC_FAILED)
return -ENOEXEC;
/* Get the pointer's value. */
if (get_user_ual(addr, rp))
return -EFAULT;
addr = flat_get_addr_from_rp(addr, relval, flags, &persistent);
if (addr != 0) {
/*
* Do the relocation. PIC relocs in the data section are
* already in target order
*/
if ((flags & FLAT_FLAG_GOTPIC) == 0)
addr = ntohl(addr);
addr = calc_reloc(addr, libinfo, id, 0);
if (addr == RELOC_FAILED)
return -ENOEXEC;
/* Write back the relocated pointer. */
if (flat_put_addr_at_rp(rp, addr, relval))
return -EFAULT;
}
}
} else {
for (i = 0; i < relocs; i++) {
abi_ulong relval;
if (get_user_ual(relval, reloc + i * sizeof(abi_ulong)))
return -EFAULT;
old_reloc(&libinfo[0], relval);
}
}
/* zero the BSS. */
memset(g2h_untagged(datapos + data_len), 0, bss_len);
return 0;
}
/****************************************************************************/
int load_flt_binary(struct linux_binprm *bprm, struct image_info *info)
{
struct lib_info libinfo[MAX_SHARED_LIBS];
abi_ulong p;
abi_ulong stack_len;
abi_ulong start_addr;
abi_ulong sp;
int res;
int i, j;
memset(libinfo, 0, sizeof(libinfo));
/*
* We have to add the size of our arguments to our stack size
* otherwise it's too easy for users to create stack overflows
* by passing in a huge argument list. And yes, we have to be
* pedantic and include space for the argv/envp array as it may have
* a lot of entries.
*/
stack_len = 0;
for (i = 0; i < bprm->argc; ++i) {
/* the argv strings */
stack_len += strlen(bprm->argv[i]);
}
for (i = 0; i < bprm->envc; ++i) {
/* the envp strings */
stack_len += strlen(bprm->envp[i]);
}
stack_len += (bprm->argc + 1) * 4; /* the argv array */
stack_len += (bprm->envc + 1) * 4; /* the envp array */
res = load_flat_file(bprm, libinfo, 0, &stack_len);
if (is_error(res)) {
return res;
}
/* Update data segment pointers for all libraries */
for (i=0; i<MAX_SHARED_LIBS; i++) {
if (libinfo[i].loaded) {
abi_ulong seg;
seg = libinfo[i].start_data;
for (j=0; j<MAX_SHARED_LIBS; j++) {
seg -= 4;
/* FIXME - handle put_user() failures */
if (put_user_ual(libinfo[j].loaded
? libinfo[j].start_data
: UNLOADED_LIB,
seg))
return -EFAULT;
}
}
}
p = ((libinfo[0].start_brk + stack_len + 3) & ~3) - 4;
DBG_FLT("p=%x\n", (int)p);
/* Copy argv/envp. */
p = copy_strings(p, bprm->envc, bprm->envp);
p = copy_strings(p, bprm->argc, bprm->argv);
/* Align stack. */
sp = p & ~(abi_ulong)(sizeof(abi_ulong) - 1);
/* Enforce final stack alignment of 16 bytes. This is sufficient
for all current targets, and excess alignment is harmless. */
stack_len = bprm->envc + bprm->argc + 2;
stack_len += flat_argvp_envp_on_stack() ? 2 : 0; /* argv, argp */
stack_len += 1; /* argc */
stack_len *= sizeof(abi_ulong);
sp -= (sp - stack_len) & 15;
sp = loader_build_argptr(bprm->envc, bprm->argc, sp, p,
flat_argvp_envp_on_stack());
/* Fake some return addresses to ensure the call chain will
* initialise library in order for us. We are required to call
* lib 1 first, then 2, ... and finally the main program (id 0).
*/
start_addr = libinfo[0].entry;
/* Stash our initial stack pointer into the mm structure */
info->start_code = libinfo[0].start_code;
info->end_code = libinfo[0].start_code + libinfo[0].text_len;
info->start_data = libinfo[0].start_data;
info->end_data = libinfo[0].end_data;
info->brk = libinfo[0].start_brk;
info->start_stack = sp;
info->stack_limit = libinfo[0].start_brk;
info->entry = start_addr;
info->code_offset = info->start_code;
info->data_offset = info->start_data - libinfo[0].text_len;
DBG_FLT("start_thread(entry=0x%x, start_stack=0x%x)\n",
(int)info->entry, (int)info->start_stack);
return 0;
}
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