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Make execve() linger when it can't spoof parent

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It's now possible to use execve() when the parent process isn't built by
cosmo. In such cases, the current process will kill all threads and then
linger around, waiting for the newly created process to die, and then we
propagate its exit code to the parent. This should help bazel and others

Allocating private anonymous memory is now 5x faster on Windows. This is
thanks to VirtualAlloc() which is faster than the file mapping APIs. The
fork() function also now goes 30% faster, since we are able to avoid the
VirtualProtect() calls on mappings in most cases now.

Fixes #1253
This commit is contained in:
Justine Tunney 2025-01-04 21:11:53 -08:00
parent c97a858470
commit 42a3bb729a
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GPG key ID: BE714B4575D6E328
40 changed files with 612 additions and 656 deletions
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27
libc/intrin/directmap-metal.c
View file

@ -19,7 +19,6 @@
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/metalfile.internal.h"
#include "libc/intrin/directmap.h"
#include "libc/macros.h"
#include "libc/runtime/pc.internal.h"
#include "libc/str/str.h"
@ -32,19 +31,11 @@
static uint64_t sys_mmap_metal_break;
static struct DirectMap bad_mmap(void) {
struct DirectMap res;
res.addr = (void *)-1;
res.maphandle = -1;
return res;
}
struct DirectMap sys_mmap_metal(void *vaddr, size_t size, int prot, int flags,
int fd, int64_t off) {
void *sys_mmap_metal(void *vaddr, size_t size, int prot, int flags, int fd,
int64_t off) {
/* asan runtime depends on this function */
size_t i;
struct mman *mm;
struct DirectMap res;
uint64_t addr, faddr = 0, page, e, *pte, *fdpte, *pml4t;
mm = __get_mm();
pml4t = __get_pml4t();
@ -54,18 +45,18 @@ struct DirectMap sys_mmap_metal(void *vaddr, size_t size, int prot, int flags,
struct Fd *sfd;
struct MetalFile *file;
if (off < 0 || fd < 0 || fd >= g_fds.n)
return bad_mmap();
return MAP_FAILED;
sfd = &g_fds.p[fd];
if (sfd->kind != kFdFile)
return bad_mmap();
return MAP_FAILED;
file = (struct MetalFile *)sfd->handle;
/* TODO: allow mapping partial page at end of file, if file size not
* multiple of page size */
if (off > file->size || size > file->size - off)
return bad_mmap();
return MAP_FAILED;
faddr = (uint64_t)file->base + off;
if (faddr % 4096 != 0)
return bad_mmap();
return MAP_FAILED;
}
if (!(flags & MAP_FIXED_linux)) {
if (!addr) {
@ -88,7 +79,7 @@ struct DirectMap sys_mmap_metal(void *vaddr, size_t size, int prot, int flags,
if ((flags & MAP_ANONYMOUS_linux)) {
page = __new_page(mm);
if (!page)
return bad_mmap();
return MAP_FAILED;
__clear_page(BANE + page);
e = page | PAGE_RSRV | PAGE_U;
if ((prot & PROT_WRITE))
@ -114,9 +105,7 @@ struct DirectMap sys_mmap_metal(void *vaddr, size_t size, int prot, int flags,
break;
}
}
res.addr = (void *)addr;
res.maphandle = -1;
return res;
return (void *)addr;
}
#endif /* __x86_64__ */