svn commit: r314929 - head/sys/kern
Gleb Smirnoff
glebius at FreeBSD.org
Thu Mar 9 00:45:17 UTC 2017
Author: glebius
Date: Thu Mar 9 00:45:15 2017
New Revision: 314929
URL: https://svnweb.freebsd.org/changeset/base/314929
Log:
Reduce stack usage in link_elf_load_file(), allocating struct nameidata.
This function may be called recursively, when a module pulls its dependencies.
Under certain circumstances, e.g. quad chain of dependencies and presence
of dtrace we may run out of stack.
Modified:
head/sys/kern/link_elf_obj.c
Modified: head/sys/kern/link_elf_obj.c
==============================================================================
--- head/sys/kern/link_elf_obj.c Thu Mar 9 00:33:38 2017 (r314928)
+++ head/sys/kern/link_elf_obj.c Thu Mar 9 00:45:15 2017 (r314929)
@@ -476,7 +476,7 @@ static int
link_elf_load_file(linker_class_t cls, const char *filename,
linker_file_t *result)
{
- struct nameidata nd;
+ struct nameidata *nd;
struct thread *td = curthread; /* XXX */
Elf_Ehdr *hdr;
Elf_Shdr *shdr;
@@ -501,18 +501,21 @@ link_elf_load_file(linker_class_t cls, c
mapsize = 0;
hdr = NULL;
- NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
+ nd = malloc(sizeof(struct nameidata), M_TEMP, M_WAITOK);
+ NDINIT(nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td);
flags = FREAD;
- error = vn_open(&nd, &flags, 0, NULL);
- if (error)
+ error = vn_open(nd, &flags, 0, NULL);
+ if (error) {
+ free(nd, M_TEMP);
return error;
- NDFREE(&nd, NDF_ONLY_PNBUF);
- if (nd.ni_vp->v_type != VREG) {
+ }
+ NDFREE(nd, NDF_ONLY_PNBUF);
+ if (nd->ni_vp->v_type != VREG) {
error = ENOEXEC;
goto out;
}
#ifdef MAC
- error = mac_kld_check_load(td->td_ucred, nd.ni_vp);
+ error = mac_kld_check_load(td->td_ucred, nd->ni_vp);
if (error) {
goto out;
}
@@ -520,7 +523,7 @@ link_elf_load_file(linker_class_t cls, c
/* Read the elf header from the file. */
hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
- error = vn_rdwr(UIO_READ, nd.ni_vp, (void *)hdr, sizeof(*hdr), 0,
+ error = vn_rdwr(UIO_READ, nd->ni_vp, (void *)hdr, sizeof(*hdr), 0,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
if (error)
@@ -577,8 +580,9 @@ link_elf_load_file(linker_class_t cls, c
}
shdr = malloc(nbytes, M_LINKER, M_WAITOK);
ef->e_shdr = shdr;
- error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes, hdr->e_shoff,
- UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid, td);
+ error = vn_rdwr(UIO_READ, nd->ni_vp, (caddr_t)shdr, nbytes,
+ hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
+ NOCRED, &resid, td);
if (error)
goto out;
if (resid) {
@@ -653,7 +657,7 @@ link_elf_load_file(linker_class_t cls, c
/* Allocate space for and load the symbol table */
ef->ddbsymcnt = shdr[symtabindex].sh_size / sizeof(Elf_Sym);
ef->ddbsymtab = malloc(shdr[symtabindex].sh_size, M_LINKER, M_WAITOK);
- error = vn_rdwr(UIO_READ, nd.ni_vp, (void *)ef->ddbsymtab,
+ error = vn_rdwr(UIO_READ, nd->ni_vp, (void *)ef->ddbsymtab,
shdr[symtabindex].sh_size, shdr[symtabindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
@@ -672,7 +676,7 @@ link_elf_load_file(linker_class_t cls, c
/* Allocate space for and load the symbol strings */
ef->ddbstrcnt = shdr[symstrindex].sh_size;
ef->ddbstrtab = malloc(shdr[symstrindex].sh_size, M_LINKER, M_WAITOK);
- error = vn_rdwr(UIO_READ, nd.ni_vp, ef->ddbstrtab,
+ error = vn_rdwr(UIO_READ, nd->ni_vp, ef->ddbstrtab,
shdr[symstrindex].sh_size, shdr[symstrindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
@@ -691,7 +695,7 @@ link_elf_load_file(linker_class_t cls, c
ef->shstrcnt = shdr[shstrindex].sh_size;
ef->shstrtab = malloc(shdr[shstrindex].sh_size, M_LINKER,
M_WAITOK);
- error = vn_rdwr(UIO_READ, nd.ni_vp, ef->shstrtab,
+ error = vn_rdwr(UIO_READ, nd->ni_vp, ef->shstrtab,
shdr[shstrindex].sh_size, shdr[shstrindex].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
&resid, td);
@@ -826,7 +830,7 @@ link_elf_load_file(linker_class_t cls, c
|| shdr[i].sh_type == SHT_X86_64_UNWIND
#endif
) {
- error = vn_rdwr(UIO_READ, nd.ni_vp,
+ error = vn_rdwr(UIO_READ, nd->ni_vp,
ef->progtab[pb].addr,
shdr[i].sh_size, shdr[i].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
@@ -867,7 +871,7 @@ link_elf_load_file(linker_class_t cls, c
M_WAITOK);
ef->reltab[rl].nrel = shdr[i].sh_size / sizeof(Elf_Rel);
ef->reltab[rl].sec = shdr[i].sh_info;
- error = vn_rdwr(UIO_READ, nd.ni_vp,
+ error = vn_rdwr(UIO_READ, nd->ni_vp,
(void *)ef->reltab[rl].rel,
shdr[i].sh_size, shdr[i].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
@@ -886,7 +890,7 @@ link_elf_load_file(linker_class_t cls, c
ef->relatab[ra].nrela =
shdr[i].sh_size / sizeof(Elf_Rela);
ef->relatab[ra].sec = shdr[i].sh_info;
- error = vn_rdwr(UIO_READ, nd.ni_vp,
+ error = vn_rdwr(UIO_READ, nd->ni_vp,
(void *)ef->relatab[ra].rela,
shdr[i].sh_size, shdr[i].sh_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
@@ -932,9 +936,9 @@ link_elf_load_file(linker_class_t cls, c
goto out;
/* Pull in dependencies */
- VOP_UNLOCK(nd.ni_vp, 0);
+ VOP_UNLOCK(nd->ni_vp, 0);
error = linker_load_dependencies(lf);
- vn_lock(nd.ni_vp, LK_EXCLUSIVE | LK_RETRY);
+ vn_lock(nd->ni_vp, LK_EXCLUSIVE | LK_RETRY);
if (error)
goto out;
@@ -954,8 +958,9 @@ link_elf_load_file(linker_class_t cls, c
*result = lf;
out:
- VOP_UNLOCK(nd.ni_vp, 0);
- vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
+ VOP_UNLOCK(nd->ni_vp, 0);
+ vn_close(nd->ni_vp, FREAD, td->td_ucred, td);
+ free(nd, M_TEMP);
if (error && lf)
linker_file_unload(lf, LINKER_UNLOAD_FORCE);
free(hdr, M_LINKER);
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