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Save memory allocation in the elf loader 

The current elf loader uses too much memory. For example, I have a
executable with a bss section of 400 MB and I set the ram size to 512
MB. Qemu uses about 780MB of RAM (which is fine), but there's a peak at
1.6 GB during initialization (this is not fine).

This patch fixes two things:
 1) do not allocate each elf program twice.
 2) do not allocate memory for areas that are only zeros.

For this we need a new field in Rom: "datasize" which is the size of the
allocated data. If datasize is less than romsize, it means that the area
from datasize to romsize is filled with zeros.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Fabien Chouteau 2013-02-19 04:41:11 +00:00 committed by Alexander Graf
parent 6bbd5dde9a
commit d60fa42e8b
3 changed files with 75 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
hw/elf_ops.h
View File

@ -197,7 +197,7 @@ static int glue(load_elf, SZ)(const char *name, int fd,
struct elfhdr ehdr;
struct elf_phdr *phdr = NULL, *ph;
int size, i, total_size;
elf_word mem_size;
elf_word mem_size, file_size;
uint64_t addr, low = (uint64_t)-1, high = 0;
uint8_t *data = NULL;
char label[128];
@ -252,14 +252,16 @@ static int glue(load_elf, SZ)(const char *name, int fd,
for(i = 0; i < ehdr.e_phnum; i++) {
ph = &phdr[i];
if (ph->p_type == PT_LOAD) {
mem_size = ph->p_memsz;
/* XXX: avoid allocating */
data = g_malloc0(mem_size);
mem_size = ph->p_memsz; /* Size of the ROM */
file_size = ph->p_filesz; /* Size of the allocated data */
data = g_malloc0(file_size);
if (ph->p_filesz > 0) {
if (lseek(fd, ph->p_offset, SEEK_SET) < 0)
if (lseek(fd, ph->p_offset, SEEK_SET) < 0) {
goto fail;
if (read(fd, data, ph->p_filesz) != ph->p_filesz)
}
if (read(fd, data, file_size) != file_size) {
goto fail;
}
}
/* address_offset is hack for kernel images that are
linked at the wrong physical address. */
@ -281,7 +283,9 @@ static int glue(load_elf, SZ)(const char *name, int fd,
}
snprintf(label, sizeof(label), "phdr #%d: %s", i, name);
rom_add_blob_fixed(label, data, mem_size, addr);
/* rom_add_elf_program() seize the ownership of 'data' */
rom_add_elf_program(label, data, file_size, mem_size, addr);
total_size += mem_size;
if (addr < low)
@ -289,7 +293,6 @@ static int glue(load_elf, SZ)(const char *name, int fd,
if ((addr + mem_size) > high)
high = addr + mem_size;
g_free(data);
data = NULL;
}
}

75
hw/loader.c
View File

@ -533,7 +533,14 @@ typedef struct Rom Rom;
struct Rom {
char *name;
char *path;
/* datasize is the amount of memory allocated in "data". If datasize is less
* than romsize, it means that the area from datasize to romsize is filled
* with zeros.
*/
size_t romsize;
size_t datasize;
uint8_t *data;
int isrom;
char *fw_dir;
@ -589,14 +596,15 @@ int rom_add_file(const char *file, const char *fw_dir,
rom->fw_dir = g_strdup(fw_dir);
rom->fw_file = g_strdup(file);
}
rom->addr = addr;
rom->romsize = lseek(fd, 0, SEEK_END);
rom->data = g_malloc0(rom->romsize);
rom->addr = addr;
rom->romsize = lseek(fd, 0, SEEK_END);
rom->datasize = rom->romsize;
rom->data = g_malloc0(rom->datasize);
lseek(fd, 0, SEEK_SET);
rc = read(fd, rom->data, rom->romsize);
if (rc != rom->romsize) {
rc = read(fd, rom->data, rom->datasize);
if (rc != rom->datasize) {
fprintf(stderr, "rom: file %-20s: read error: rc=%d (expected %zd)\n",
rom->name, rc, rom->romsize);
rom->name, rc, rom->datasize);
goto err;
}
close(fd);
@ -637,16 +645,37 @@ int rom_add_blob(const char *name, const void *blob, size_t len,
{
Rom *rom;
rom = g_malloc0(sizeof(*rom));
rom->name = g_strdup(name);
rom->addr = addr;
rom->romsize = len;
rom->data = g_malloc0(rom->romsize);
rom = g_malloc0(sizeof(*rom));
rom->name = g_strdup(name);
rom->addr = addr;
rom->romsize = len;
rom->datasize = len;
rom->data = g_malloc0(rom->datasize);
memcpy(rom->data, blob, len);
rom_insert(rom);
return 0;
}
/* This function is specific for elf program because we don't need to allocate
* all the rom. We just allocate the first part and the rest is just zeros. This
* is why romsize and datasize are different. Also, this function seize the
* memory ownership of "data", so we don't have to allocate and copy the buffer.
*/
int rom_add_elf_program(const char *name, void *data, size_t datasize,
size_t romsize, hwaddr addr)
{
Rom *rom;
rom = g_malloc0(sizeof(*rom));
rom->name = g_strdup(name);
rom->addr = addr;
rom->datasize = datasize;
rom->romsize = romsize;
rom->data = data;
rom_insert(rom);
return 0;
}
int rom_add_vga(const char *file)
{
return rom_add_file(file, "vgaroms", 0, -1);
@ -668,7 +697,7 @@ static void rom_reset(void *unused)
if (rom->data == NULL) {
continue;
}
cpu_physical_memory_write_rom(rom->addr, rom->data, rom->romsize);
cpu_physical_memory_write_rom(rom->addr, rom->data, rom->datasize);
if (rom->isrom) {
/* rom needs to be written only once */
g_free(rom->data);
@ -756,13 +785,33 @@ int rom_copy(uint8_t *dest, hwaddr addr, size_t size)
d = dest + (rom->addr - addr);
s = rom->data;
l = rom->romsize;
l = rom->datasize;
if ((d + l) > (dest + size)) {
l = dest - d;
}
memcpy(d, s, l);
if (rom->romsize > rom->datasize) {
/* If datasize is less than romsize, it means that we didn't
* allocate all the ROM because the trailing data are only zeros.
*/
d += l;
l = rom->romsize - rom->datasize;
if ((d + l) > (dest + size)) {
/* Rom size doesn't fit in the destination area. Adjust to avoid
* overflow.
*/
l = dest - d;
}
if (l > 0) {
memset(d, 0x0, l);
}
}
}
return (d + l) - dest;

2
hw/loader.h
View File

@ -27,6 +27,8 @@ int rom_add_file(const char *file, const char *fw_dir,
hwaddr addr, int32_t bootindex);
int rom_add_blob(const char *name, const void *blob, size_t len,
hwaddr addr);
int rom_add_elf_program(const char *name, void *data, size_t datasize,
size_t romsize, hwaddr addr);
int rom_load_all(void);
void rom_set_fw(void *f);
int rom_copy(uint8_t *dest, hwaddr addr, size_t size);