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elf: fix zeroing of first loaded page, header base and stack alignment

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Matheus
2023-05-07 22:36:14 -03:00
parent 41f3283715
commit fa97996fcc
1 changed files with 37 additions and 14 deletions
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kernel-src/sys/elf.c
+37 -14
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@@ -29,9 +29,9 @@ static bool headerok(elfheader64_t *header) {
return true;
}
static int readexact(vnode_t *vnode, void *pos, size_t count, uintmax_t offset) {
static int readexact(vnode_t *vnode, void *buff, size_t count, uintmax_t offset) {
size_t readc;
int e = vfs_read(vnode, pos, count, offset, &readc, 0);
int e = vfs_read(vnode, buff, count, offset, &readc, 0);
if (e)
return e;
if (readc != count)
@@ -53,7 +53,6 @@ static mmuflags_t flagstommuflags(int flags) {
static int load(vnode_t *vnode, elfph64_t *ph) {
// TODO verify that the load address doesn't intersect the kernel
printf("loading ph at %p with mem size %lu, disk size %lu and flags %x\n", ph->memaddr, ph->msize, ph->fsize, ph->flags);
int error = 0;
uintmax_t foffset = ph->offset;
uintptr_t mempos = ph->memaddr;
@@ -81,6 +80,14 @@ static int load(vnode_t *vnode, elfph64_t *ph) {
msize -= firstpagecount;
fsize -= firstpagecount;
foffset += firstpagecount;
uintmax_t remaining = mempos % PAGE_SIZE;
// zero remaining parts of the first page if needed
if (remaining && msize) {
size_t remainingmsize = remaining > msize ? msize : remaining;
memset((void *)mempos, 0, remainingmsize);
msize -= remainingmsize;
mempos += remainingmsize;
}
}
// map middle of file
@@ -149,7 +156,7 @@ int elf_load(vnode_t *vnode, void *base, void **entry, char **interpreter, auxv6
auxv64->phnum.val = header.phcount;
auxv64->phent.val = header.phsize;
auxv64->entry.val = header.entry;
*entry = (void *)header.entry;
*entry = (void *)(header.entry + (uintptr_t)base);
__assert(header.phsize == sizeof(elfph64_t));
@@ -165,6 +172,7 @@ int elf_load(vnode_t *vnode, void *base, void **entry, char **interpreter, auxv6
elfph64_t *interpreterph = NULL;
for (int i = 0; i < header.phcount; ++i) {
headers[i].memaddr += (uintptr_t)base;
switch (headers[i].type) {
case PH_TYPE_INTERPRETER:
interpreterph = &headers[i];
@@ -173,7 +181,6 @@ int elf_load(vnode_t *vnode, void *base, void **entry, char **interpreter, auxv6
auxv64->phdr.val = headers[i].memaddr;
break;
case PH_TYPE_LOAD:
headers[i].memaddr += (uintptr_t)base;
err = load(vnode, &headers[i]);
if (err)
goto cleanup;
@@ -182,8 +189,15 @@ int elf_load(vnode_t *vnode, void *base, void **entry, char **interpreter, auxv6
}
if (interpreterph) {
printf("dp: %lu dl: %lu mp: %p ml: %lu\n", interpreterph->offset, interpreterph->fsize, interpreterph->memaddr, interpreterph->msize);
__assert(!"UNIMPLEMENTED");
char *buff = alloc(interpreterph->fsize);
if (buff == NULL) {
err = ENOMEM;
goto cleanup;
}
err = readexact(vnode, buff, interpreterph->fsize, interpreterph->offset);
if (err)
goto cleanup;
*interpreter = buff;
}
cleanup:
@@ -192,6 +206,7 @@ int elf_load(vnode_t *vnode, void *base, void **entry, char **interpreter, auxv6
}
#define STACK_MMUFLAGS (ARCH_MMU_FLAGS_READ | ARCH_MMU_FLAGS_WRITE | ARCH_MMU_FLAGS_NOEXEC | ARCH_MMU_FLAGS_USER)
#define STACK_SIZE (1024 * 1024 * 4)
void *elf_preparestack(void *top, auxv64list_t *auxv64, char **argv, char **envp) {
size_t argc;
@@ -205,23 +220,31 @@ void *elf_preparestack(void *top, auxv64list_t *auxv64, char **argv, char **envp
for (envc = 0; envp[envc]; ++envc)
envdatasize += strlen(envp[envc]) + 1;
// make sure stack will be 16 byte aligned on entry
int alignment = ((argc + 1) + (envc + 1) + 1) & 1 ? 8 : 0;
// env data + arg data + pointers to arg and env data + argc
size_t initialsize = argdatasize + envdatasize + (argc + envc) * sizeof(char *) + sizeof(size_t) + sizeof(auxv64list_t);
size_t initialsize = argdatasize + envdatasize + (argc + envc) * sizeof(char *) + sizeof(size_t) + sizeof(auxv64list_t) + alignment;
size_t initialsizeround = ROUND_UP(initialsize, PAGE_SIZE);
void *initialpagebase = (void *)((uintptr_t)top - initialsizeround);
if (vmm_map(initialpagebase, initialsizeround, VMM_FLAGS_ALLOCATE | VMM_FLAGS_EXACT, STACK_MMUFLAGS, NULL) == NULL)
return NULL;
auxv64list_t *auxvstart = (auxv64list_t *)top - 1;
char *argdatastart = (char *)((uintptr_t)auxvstart - argdatasize);
void *stackbase = (void *)((uintptr_t)top - STACK_SIZE);
size_t unallocatedsize = STACK_SIZE - initialsizeround;
if (vmm_map(stackbase, unallocatedsize, VMM_FLAGS_EXACT, STACK_MMUFLAGS, NULL) == NULL)
return NULL;
char *argdatastart = (char *)((uintptr_t)top - argdatasize);
char *envdatastart = (char *)((uintptr_t)argdatastart - envdatasize);
auxv64list_t *auxvstart = (auxv64list_t *)envdatastart - 1;
auxvstart = (auxv64list_t *)(((uintptr_t)auxvstart & ~(uintptr_t)0xf) - alignment);
// also leave space for null entry
char **envstart = (char **)envdatastart - envc - 1;
// round down to 16 bytes
envstart = (char **)((uintptr_t)envstart & ~(uintptr_t)0xf);
char **envstart = (char **)auxvstart - envc - 1;
char **argstart = (char **)envstart - argc - 1;
size_t *argcptr = (size_t *)argstart - 1;