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 <chout...@adacore.com> --- hw/elf_ops.h | 18 ++++++++------ hw/loader.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++----------- hw/loader.h | 2 + 3 files changed, 72 insertions(+), 22 deletions(-) diff --git a/hw/elf_ops.h b/hw/elf_ops.h index 6af357f..3bfc575 100644 --- a/hw/elf_ops.h +++ b/hw/elf_ops.h @@ -199,7 +199,7 @@ 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]; @@ -254,14 +254,16 @@ 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. */ @@ -272,7 +274,8 @@ 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(label, data, file_size, mem_size, addr); total_size += mem_size; if (addr < low) @@ -280,7 +283,6 @@ 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; } } diff --git a/hw/loader.c b/hw/loader.c index 9bbcddd..224666d 100644 --- a/hw/loader.c +++ b/hw/loader.c @@ -527,7 +527,14 @@ 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; @@ -583,14 +590,15 @@ 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); @@ -631,16 +639,37 @@ 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. That + * 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, target_phys_addr_t 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); @@ -662,7 +691,7 @@ 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); @@ -751,13 +780,30 @@ int rom_copy(uint8_t *dest, target_phys_addr_t 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)) { + l = dest - d; + } + + if (l > 0) { + memset(d, 0x0, l); + } + } } return (d + l) - dest; @@ -786,7 +832,7 @@ void do_info_roms(Monitor *mon) rom->name); } else { monitor_printf(mon, "fw=%s/%s" - " size=0x%06zx name=\"%s\"\n", + " size=0x%06zx name=\"%s\"\n", rom->fw_dir, rom->fw_file, rom->romsize, diff --git a/hw/loader.h b/hw/loader.h index fbcaba9..a941448 100644 --- a/hw/loader.h +++ b/hw/loader.h @@ -25,6 +25,8 @@ int rom_add_file(const char *file, const char *fw_dir, target_phys_addr_t addr, int32_t bootindex); int rom_add_blob(const char *name, const void *blob, size_t len, target_phys_addr_t addr); +int rom_add_elf_program(const char *name, void *data, size_t datasize, + size_t romsize, target_phys_addr_t addr); int rom_load_all(void); void rom_set_fw(void *f); int rom_copy(uint8_t *dest, target_phys_addr_t addr, size_t size); -- 1.7.4.1