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Add support for kernel modules with a single PT_LOAD section.

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While here, support up to four sections because it was trivial to do
and cheap. (One pointer per section).

For amd64 with "-fpic -shared" format .ko files, using a single PT_LOAD
section is important to avoid wasting about 1MB of KVM and physical ram
for the 'gap' between the two PT_LOAD sections.  amd64 normally uses
.o format kld files and isn't affected normally.  But -fpic -shared modules
are actually possible to produce and load...  (And with a bugfix to
binutils, we can build and use plain -shared .ko files without -fpic)

i386 only wastes 4K per .ko file, so that isn't such a big deal there.
This commit is contained in:
Peter Wemm 2005-10-17 23:21:55 +00:00
parent 9313eb5537
commit 1a330eb01d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=151430
1 changed files with 9 additions and 6 deletions
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15
sys/kern/link_elf.c
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@ -62,6 +62,8 @@ __FBSDID("$FreeBSD$");
#include "linker_if.h"
#define MAXSEGS 4
typedef struct elf_file {
struct linker_file lf; /* Common fields */
int preloaded; /* Was file pre-loaded */
@ -536,7 +538,7 @@ link_elf_load_file(linker_class_t cls, const char* filename,
int nbytes, i;
Elf_Phdr *phdr;
Elf_Phdr *phlimit;
Elf_Phdr *segs[2];
Elf_Phdr *segs[MAXSEGS];
int nsegs;
Elf_Phdr *phdyn;
Elf_Phdr *phphdr;
@ -643,7 +645,7 @@ link_elf_load_file(linker_class_t cls, const char* filename,
switch (phdr->p_type) {
case PT_LOAD:
if (nsegs == 2) {
if (nsegs == MAXSEGS) {
link_elf_error("Too many sections");
error = ENOEXEC;
goto out;
@ -676,8 +678,8 @@ link_elf_load_file(linker_class_t cls, const char* filename,
error = ENOEXEC;
goto out;
}
if (nsegs != 2) {
link_elf_error("Too few sections");
if (nsegs == 0) {
link_elf_error("No sections");
error = ENOEXEC;
goto out;
}
@ -688,7 +690,8 @@ link_elf_load_file(linker_class_t cls, const char* filename,
*/
base_offset = trunc_page(segs[0]->p_offset);
base_vaddr = trunc_page(segs[0]->p_vaddr);
base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
base_vlimit = round_page(segs[nsegs - 1]->p_vaddr +
segs[nsegs - 1]->p_memsz);
mapsize = base_vlimit - base_vaddr;
lf = linker_make_file(filename, &link_elf_class);
@ -726,7 +729,7 @@ link_elf_load_file(linker_class_t cls, const char* filename,
/*
* Read the text and data sections and zero the bss.
*/
for (i = 0; i < 2; i++) {
for (i = 0; i < nsegs; i++) {
caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
error = vn_rdwr(UIO_READ, nd.ni_vp,
segbase, segs[i]->p_filesz, segs[i]->p_offset,