diff options
Diffstat (limited to 'usr/src/uts/common/os/exec.c')
| -rw-r--r-- | usr/src/uts/common/os/exec.c | 54 |
1 files changed, 45 insertions, 9 deletions
diff --git a/usr/src/uts/common/os/exec.c b/usr/src/uts/common/os/exec.c index e896bbd1e5..d044b2a08d 100644 --- a/usr/src/uts/common/os/exec.c +++ b/usr/src/uts/common/os/exec.c @@ -26,7 +26,7 @@ /* Copyright (c) 1988 AT&T */ /* All Rights Reserved */ /* - * Copyright (c) 2012, Joyent, Inc. All rights reserved. + * Copyright 2014, Joyent, Inc. All rights reserved. */ #include <sys/types.h> @@ -1270,6 +1270,33 @@ execmap(struct vnode *vp, caddr_t addr, size_t len, size_t zfodlen, /* * Before we go to zero the remaining space on the last * page, make sure we have write permission. + * + * Normal illumos binaries don't even hit the case + * where we have to change permission on the last page + * since their protection is typically either + * PROT_USER | PROT_WRITE | PROT_READ + * or + * PROT_ZFOD (same as PROT_ALL). + * + * We need to be careful how we zero-fill the last page + * if the segment protection does not include + * PROT_WRITE. We don't want to use as_setprot() to + * temporarily change the last page's prot to enable + * PROT_WRITE, since that can cause the VM segment code + * to call seg*_vpage(), which will allocate a page + * struct for each page in the segment. If we have a + * very large segment, this will either use a large + * amount of kernel memory, or possibly never finish + * because page_resv() will never obtain enough free + * pages. + * + * Instead, we temporarily change the protection on the + * entire segment so that we can zero-fill the last + * page, then change the protection back. + * + * Because we are working with the entire segement, the + * VM code does not need to allocate per-page structs + * to keep track of permissions. */ AS_LOCK_ENTER(as, &as->a_lock, RW_READER); @@ -1280,23 +1307,32 @@ execmap(struct vnode *vp, caddr_t addr, size_t len, size_t zfodlen, AS_LOCK_EXIT(as, &as->a_lock); if (seg != NULL && (zprot & PROT_WRITE) == 0) { - (void) as_setprot(as, (caddr_t)end, - zfoddiff - 1, zprot | PROT_WRITE); + AS_LOCK_ENTER(as, &as->a_lock, RW_WRITER); + (void) SEGOP_SETPROT(seg, seg->s_base, + seg->s_size, zprot | PROT_WRITE); + AS_LOCK_EXIT(as, &as->a_lock); } if (on_fault(&ljb)) { no_fault(); - if (seg != NULL && (zprot & PROT_WRITE) == 0) - (void) as_setprot(as, (caddr_t)end, - zfoddiff - 1, zprot); + if (seg != NULL && (zprot & PROT_WRITE) == 0) { + AS_LOCK_ENTER(as, &as->a_lock, + RW_WRITER); + (void) SEGOP_SETPROT(seg, seg->s_base, + seg->s_size, zprot); + AS_LOCK_EXIT(as, &as->a_lock); + } error = EFAULT; goto bad; } uzero((void *)end, zfoddiff); no_fault(); - if (seg != NULL && (zprot & PROT_WRITE) == 0) - (void) as_setprot(as, (caddr_t)end, - zfoddiff - 1, zprot); + if (seg != NULL && (zprot & PROT_WRITE) == 0) { + AS_LOCK_ENTER(as, &as->a_lock, RW_WRITER); + (void) SEGOP_SETPROT(seg, seg->s_base, + seg->s_size, zprot); + AS_LOCK_EXIT(as, &as->a_lock); + } } if (zfodlen > zfoddiff) { struct segvn_crargs crargs = |