Fix some problems with the SPARSE_MAPPING option in the kernel linker.
- Ensure that the end of the mapping passed to vm_page_wire() is page-aligned. vm_page_wire() expects this. - Wire pages before reading data into them. - Apply protections specified in the segment descriptor using vm_map_protect() once relocation processing is done. - On amd64, ensure that we load KLDs above KERNBASE, since they are compiled with the "kernel" memory model by default. Reviewed by: kib MFC after: 2 weeks Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D21756
This commit is contained in:
Mark Johnston
parent
d4586dd328
commit
1aa696babc
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=352829
@ -40,6 +40,9 @@ __FBSDID("$FreeBSD$");
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#ifdef SPARSE_MAPPING
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#include <sys/mman.h>
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#endif
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#include <sys/mutex.h>
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#include <sys/mount.h>
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#include <sys/pcpu.h>
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@ -419,7 +422,7 @@ link_elf_init(void* arg)
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ef->address = 0;
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#endif
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#ifdef SPARSE_MAPPING
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ef->object = 0;
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ef->object = NULL;
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#endif
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ef->dynamic = dp;
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@ -772,7 +775,7 @@ link_elf_link_preload(linker_class_t cls,
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ef->modptr = modptr;
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ef->address = *(caddr_t *)baseptr;
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#ifdef SPARSE_MAPPING
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ef->object = 0;
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ef->object = NULL;
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#endif
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dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr;
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ef->dynamic = (Elf_Dyn *)dp;
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@ -826,7 +829,7 @@ link_elf_load_file(linker_class_t cls, const char* filename,
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struct nameidata nd;
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struct thread* td = curthread; /* XXX */
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Elf_Ehdr *hdr;
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caddr_t firstpage;
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caddr_t firstpage, segbase;
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int nbytes, i;
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Elf_Phdr *phdr;
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Elf_Phdr *phlimit;
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@ -993,25 +996,53 @@ link_elf_load_file(linker_class_t cls, const char* filename,
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error = ENOMEM;
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goto out;
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}
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ef->address = (caddr_t) vm_map_min(kernel_map);
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#ifdef __amd64__
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mapbase = (caddr_t)KERNBASE;
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#else
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mapbase = (caddr_t)vm_map_min(kernel_map);
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#endif
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/*
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* Mapping protections are downgraded after relocation processing.
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*/
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error = vm_map_find(kernel_map, ef->object, 0,
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(vm_offset_t *) &ef->address, mapsize, 0, VMFS_OPTIMAL_SPACE,
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(vm_offset_t *)&mapbase, mapsize, 0, VMFS_OPTIMAL_SPACE,
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VM_PROT_ALL, VM_PROT_ALL, 0);
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if (error != 0) {
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vm_object_deallocate(ef->object);
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ef->object = 0;
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ef->object = NULL;
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goto out;
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}
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#else
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ef->address = malloc(mapsize, M_LINKER, M_EXEC | M_WAITOK);
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mapbase = malloc(mapsize, M_LINKER, M_EXEC | M_WAITOK);
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#endif
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mapbase = ef->address;
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ef->address = mapbase;
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/*
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* Read the text and data sections and zero the bss.
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*/
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for (i = 0; i < nsegs; i++) {
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caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
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segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
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#ifdef SPARSE_MAPPING
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/*
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* Consecutive segments may have different mapping permissions,
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* so be strict and verify that their mappings do not overlap.
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*/
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if (((vm_offset_t)segbase & PAGE_MASK) != 0) {
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error = EINVAL;
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goto out;
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}
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error = vm_map_wire(kernel_map,
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(vm_offset_t)segbase,
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(vm_offset_t)segbase + round_page(segs[i]->p_memsz),
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VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
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if (error != KERN_SUCCESS) {
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error = ENOMEM;
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goto out;
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}
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#endif
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error = vn_rdwr(UIO_READ, nd.ni_vp,
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segbase, segs[i]->p_filesz, segs[i]->p_offset,
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UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
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@ -1020,20 +1051,6 @@ link_elf_load_file(linker_class_t cls, const char* filename,
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goto out;
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bzero(segbase + segs[i]->p_filesz,
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segs[i]->p_memsz - segs[i]->p_filesz);
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#ifdef SPARSE_MAPPING
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/*
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* Wire down the pages
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*/
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error = vm_map_wire(kernel_map,
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(vm_offset_t) segbase,
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(vm_offset_t) segbase + segs[i]->p_memsz,
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VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
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if (error != KERN_SUCCESS) {
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error = ENOMEM;
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goto out;
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}
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#endif
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}
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#ifdef GPROF
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@ -1071,6 +1088,34 @@ link_elf_load_file(linker_class_t cls, const char* filename,
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if (error != 0)
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goto out;
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#ifdef SPARSE_MAPPING
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/*
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* Downgrade permissions on text segment mappings now that relocation
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* processing is complete. Restrict permissions on read-only segments.
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*/
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for (i = 0; i < nsegs; i++) {
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vm_prot_t prot;
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if (segs[i]->p_type != PT_LOAD)
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continue;
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prot = VM_PROT_READ;
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if ((segs[i]->p_flags & PF_W) != 0)
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prot |= VM_PROT_WRITE;
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if ((segs[i]->p_flags & PF_X) != 0)
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prot |= VM_PROT_EXECUTE;
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segbase = mapbase + segs[i]->p_vaddr - base_vaddr;
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error = vm_map_protect(kernel_map,
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(vm_offset_t)segbase,
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(vm_offset_t)segbase + round_page(segs[i]->p_memsz),
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prot, FALSE);
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if (error != KERN_SUCCESS) {
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error = ENOMEM;
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goto out;
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}
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}
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#endif
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/*
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* Try and load the symbol table if it's present. (you can
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* strip it!)
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