titaniumtown/os161-assignments
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

clang-format

Browse Source
This commit is contained in:
Simon Gardling
2024-09-10 13:03:02 -04:00
parent 53c617d779
commit d66450e427
381 changed files with 28864 additions and 34170 deletions
Download Patch File Download Diff File Expand all files Collapse all files

355
kern/syscall/loadelf.c
View File

@@ -27,7 +27,6 @@
* SUCH DAMAGE.
*/
/*
* Code to load an ELF-format executable into the current address space.
*
@@ -74,60 +73,56 @@
* change this code to not use uiomove, be sure to check for this case
* explicitly.
*/
static
int
load_segment(struct addrspace *as, struct vnode *v,
off_t offset, vaddr_t vaddr,
size_t memsize, size_t filesize,
int is_executable)
{
struct iovec iov;
struct uio u;
int result;
static int load_segment(struct addrspace *as, struct vnode *v, off_t offset,
vaddr_t vaddr, size_t memsize, size_t filesize,
int is_executable) {
struct iovec iov;
struct uio u;
int result;
if (filesize > memsize) {
kprintf("ELF: warning: segment filesize > segment memsize\n");
filesize = memsize;
}
if (filesize > memsize) {
kprintf("ELF: warning: segment filesize > segment memsize\n");
filesize = memsize;
}
DEBUG(DB_EXEC, "ELF: Loading %lu bytes to 0x%lx\n",
(unsigned long) filesize, (unsigned long) vaddr);
DEBUG(DB_EXEC, "ELF: Loading %lu bytes to 0x%lx\n", (unsigned long)filesize,
(unsigned long)vaddr);
iov.iov_ubase = (userptr_t)vaddr;
iov.iov_len = memsize; // length of the memory space
u.uio_iov = &iov;
u.uio_iovcnt = 1;
u.uio_resid = filesize; // amount to read from the file
u.uio_offset = offset;
u.uio_segflg = is_executable ? UIO_USERISPACE : UIO_USERSPACE;
u.uio_rw = UIO_READ;
u.uio_space = as;
iov.iov_ubase = (userptr_t)vaddr;
iov.iov_len = memsize; // length of the memory space
u.uio_iov = &iov;
u.uio_iovcnt = 1;
u.uio_resid = filesize; // amount to read from the file
u.uio_offset = offset;
u.uio_segflg = is_executable ? UIO_USERISPACE : UIO_USERSPACE;
u.uio_rw = UIO_READ;
u.uio_space = as;
result = VOP_READ(v, &u);
if (result) {
return result;
}
result = VOP_READ(v, &u);
if (result) {
return result;
}
if (u.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on segment - file truncated?\n");
return ENOEXEC;
}
if (u.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on segment - file truncated?\n");
return ENOEXEC;
}
/*
* If memsize > filesize, the remaining space should be
* zero-filled. There is no need to do this explicitly,
* because the VM system should provide pages that do not
* contain other processes' data, i.e., are already zeroed.
*
* During development of your VM system, it may have bugs that
* cause it to (maybe only sometimes) not provide zero-filled
* pages, which can cause user programs to fail in strange
* ways. Explicitly zeroing program BSS may help identify such
* bugs, so the following disabled code is provided as a
* diagnostic tool. Note that it must be disabled again before
* you submit your code for grading.
*/
/*
* If memsize > filesize, the remaining space should be
* zero-filled. There is no need to do this explicitly,
* because the VM system should provide pages that do not
* contain other processes' data, i.e., are already zeroed.
*
* During development of your VM system, it may have bugs that
* cause it to (maybe only sometimes) not provide zero-filled
* pages, which can cause user programs to fail in strange
* ways. Explicitly zeroing program BSS may help identify such
* bugs, so the following disabled code is provided as a
* diagnostic tool. Note that it must be disabled again before
* you submit your code for grading.
*/
#if 0
{
size_t fillamt;
@@ -142,7 +137,7 @@ load_segment(struct addrspace *as, struct vnode *v,
}
#endif
return result;
return result;
}
/*
@@ -150,158 +145,154 @@ load_segment(struct addrspace *as, struct vnode *v,
*
* Returns the entry point (initial PC) for the program in ENTRYPOINT.
*/
int
load_elf(struct vnode *v, vaddr_t *entrypoint)
{
Elf_Ehdr eh; /* Executable header */
Elf_Phdr ph; /* "Program header" = segment header */
int result, i;
struct iovec iov;
struct uio ku;
struct addrspace *as;
int load_elf(struct vnode *v, vaddr_t *entrypoint) {
Elf_Ehdr eh; /* Executable header */
Elf_Phdr ph; /* "Program header" = segment header */
int result, i;
struct iovec iov;
struct uio ku;
struct addrspace *as;
as = proc_getas();
as = proc_getas();
/*
* Read the executable header from offset 0 in the file.
*/
/*
* Read the executable header from offset 0 in the file.
*/
uio_kinit(&iov, &ku, &eh, sizeof(eh), 0, UIO_READ);
result = VOP_READ(v, &ku);
if (result) {
return result;
}
uio_kinit(&iov, &ku, &eh, sizeof(eh), 0, UIO_READ);
result = VOP_READ(v, &ku);
if (result) {
return result;
}
if (ku.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on header - file truncated?\n");
return ENOEXEC;
}
if (ku.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on header - file truncated?\n");
return ENOEXEC;
}
/*
* Check to make sure it's a 32-bit ELF-version-1 executable
* for our processor type. If it's not, we can't run it.
*
* Ignore EI_OSABI and EI_ABIVERSION - properly, we should
* define our own, but that would require tinkering with the
* linker to have it emit our magic numbers instead of the
* default ones. (If the linker even supports these fields,
* which were not in the original elf spec.)
*/
/*
* Check to make sure it's a 32-bit ELF-version-1 executable
* for our processor type. If it's not, we can't run it.
*
* Ignore EI_OSABI and EI_ABIVERSION - properly, we should
* define our own, but that would require tinkering with the
* linker to have it emit our magic numbers instead of the
* default ones. (If the linker even supports these fields,
* which were not in the original elf spec.)
*/
if (eh.e_ident[EI_MAG0] != ELFMAG0 ||
eh.e_ident[EI_MAG1] != ELFMAG1 ||
eh.e_ident[EI_MAG2] != ELFMAG2 ||
eh.e_ident[EI_MAG3] != ELFMAG3 ||
eh.e_ident[EI_CLASS] != ELFCLASS32 ||
eh.e_ident[EI_DATA] != ELFDATA2MSB ||
eh.e_ident[EI_VERSION] != EV_CURRENT ||
eh.e_version != EV_CURRENT ||
eh.e_type!=ET_EXEC ||
eh.e_machine!=EM_MACHINE) {
return ENOEXEC;
}
if (eh.e_ident[EI_MAG0] != ELFMAG0 || eh.e_ident[EI_MAG1] != ELFMAG1 ||
eh.e_ident[EI_MAG2] != ELFMAG2 || eh.e_ident[EI_MAG3] != ELFMAG3 ||
eh.e_ident[EI_CLASS] != ELFCLASS32 ||
eh.e_ident[EI_DATA] != ELFDATA2MSB ||
eh.e_ident[EI_VERSION] != EV_CURRENT || eh.e_version != EV_CURRENT ||
eh.e_type != ET_EXEC || eh.e_machine != EM_MACHINE) {
return ENOEXEC;
}
/*
* Go through the list of segments and set up the address space.
*
* Ordinarily there will be one code segment, one read-only
* data segment, and one data/bss segment, but there might
* conceivably be more. You don't need to support such files
* if it's unduly awkward to do so.
*
* Note that the expression eh.e_phoff + i*eh.e_phentsize is
* mandated by the ELF standard - we use sizeof(ph) to load,
* because that's the structure we know, but the file on disk
* might have a larger structure, so we must use e_phentsize
* to find where the phdr starts.
*/
/*
* Go through the list of segments and set up the address space.
*
* Ordinarily there will be one code segment, one read-only
* data segment, and one data/bss segment, but there might
* conceivably be more. You don't need to support such files
* if it's unduly awkward to do so.
*
* Note that the expression eh.e_phoff + i*eh.e_phentsize is
* mandated by the ELF standard - we use sizeof(ph) to load,
* because that's the structure we know, but the file on disk
* might have a larger structure, so we must use e_phentsize
* to find where the phdr starts.
*/
for (i=0; i<eh.e_phnum; i++) {
off_t offset = eh.e_phoff + i*eh.e_phentsize;
uio_kinit(&iov, &ku, &ph, sizeof(ph), offset, UIO_READ);
for (i = 0; i < eh.e_phnum; i++) {
off_t offset = eh.e_phoff + i * eh.e_phentsize;
uio_kinit(&iov, &ku, &ph, sizeof(ph), offset, UIO_READ);
result = VOP_READ(v, &ku);
if (result) {
return result;
}
result = VOP_READ(v, &ku);
if (result) {
return result;
}
if (ku.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on phdr - file truncated?\n");
return ENOEXEC;
}
if (ku.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on phdr - file truncated?\n");
return ENOEXEC;
}
switch (ph.p_type) {
case PT_NULL: /* skip */ continue;
case PT_PHDR: /* skip */ continue;
case PT_MIPS_REGINFO: /* skip */ continue;
case PT_LOAD: break;
default:
kprintf("loadelf: unknown segment type %d\n",
ph.p_type);
return ENOEXEC;
}
switch (ph.p_type) {
case PT_NULL: /* skip */
continue;
case PT_PHDR: /* skip */
continue;
case PT_MIPS_REGINFO: /* skip */
continue;
case PT_LOAD:
break;
default:
kprintf("loadelf: unknown segment type %d\n", ph.p_type);
return ENOEXEC;
}
result = as_define_region(as,
ph.p_vaddr, ph.p_memsz,
ph.p_flags & PF_R,
ph.p_flags & PF_W,
ph.p_flags & PF_X);
if (result) {
return result;
}
}
result = as_define_region(as, ph.p_vaddr, ph.p_memsz, ph.p_flags & PF_R,
ph.p_flags & PF_W, ph.p_flags & PF_X);
if (result) {
return result;
}
}
result = as_prepare_load(as);
if (result) {
return result;
}
result = as_prepare_load(as);
if (result) {
return result;
}
/*
* Now actually load each segment.
*/
/*
* Now actually load each segment.
*/
for (i=0; i<eh.e_phnum; i++) {
off_t offset = eh.e_phoff + i*eh.e_phentsize;
uio_kinit(&iov, &ku, &ph, sizeof(ph), offset, UIO_READ);
for (i = 0; i < eh.e_phnum; i++) {
off_t offset = eh.e_phoff + i * eh.e_phentsize;
uio_kinit(&iov, &ku, &ph, sizeof(ph), offset, UIO_READ);
result = VOP_READ(v, &ku);
if (result) {
return result;
}
result = VOP_READ(v, &ku);
if (result) {
return result;
}
if (ku.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on phdr - file truncated?\n");
return ENOEXEC;
}
if (ku.uio_resid != 0) {
/* short read; problem with executable? */
kprintf("ELF: short read on phdr - file truncated?\n");
return ENOEXEC;
}
switch (ph.p_type) {
case PT_NULL: /* skip */ continue;
case PT_PHDR: /* skip */ continue;
case PT_MIPS_REGINFO: /* skip */ continue;
case PT_LOAD: break;
default:
kprintf("loadelf: unknown segment type %d\n",
ph.p_type);
return ENOEXEC;
}
switch (ph.p_type) {
case PT_NULL: /* skip */
continue;
case PT_PHDR: /* skip */
continue;
case PT_MIPS_REGINFO: /* skip */
continue;
case PT_LOAD:
break;
default:
kprintf("loadelf: unknown segment type %d\n", ph.p_type);
return ENOEXEC;
}
result = load_segment(as, v, ph.p_offset, ph.p_vaddr,
ph.p_memsz, ph.p_filesz,
ph.p_flags & PF_X);
if (result) {
return result;
}
}
result = load_segment(as, v, ph.p_offset, ph.p_vaddr, ph.p_memsz,
ph.p_filesz, ph.p_flags & PF_X);
if (result) {
return result;
}
}
result = as_complete_load(as);
if (result) {
return result;
}
result = as_complete_load(as);
if (result) {
return result;
}
*entrypoint = eh.e_entry;
*entrypoint = eh.e_entry;
return 0;
return 0;
}