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Reduce stack usage in link_elf_load_file(), allocating struct nameidata.

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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.
This commit is contained in:
Gleb Smirnoff 2017-03-09 00:45:15 +00:00
parent 2bcbcb593d
commit a344babf78
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=314929
1 changed files with 25 additions and 20 deletions
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45
sys/kern/link_elf_obj.c
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@ -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, const char *filename,
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, const char *filename,
/* 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, const char *filename,
}
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, const char *filename,
/* 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, const char *filename,
/* 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, const char *filename,
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, const char *filename,
|| 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, const char *filename,
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, const char *filename,
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, const char *filename,
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, const char *filename,
*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);