| Message ID | 1471058305-30198-5-git-send-email-bauerman@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, 13 Aug 2016 00:18:23 -0300 Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> wrote: > kexec_update_segment allows a given segment in kexec_image to have > its contents updated. This is useful if the current kernel wants to > send information to the next kernel that is up-to-date at the time of > reboot. > > ... > > @@ -721,6 +721,105 @@ static struct page *kimage_alloc_page(struct kimage *image, > return page; > } > > +/** > + * kexec_update_segment - update the contents of a kimage segment > + * @buffer: New contents of the segment. > + * @bufsz: @buffer size. > + * @load_addr: Segment's physical address in the next kernel. > + * @memsz: Segment size. > + * > + * This function assumes kexec_mutex is held. > + * > + * Return: 0 on success, negative errno on error. > + */ > +int kexec_update_segment(const char *buffer, unsigned long bufsz, > + unsigned long load_addr, unsigned long memsz) > +{ > + int i; > + unsigned long entry; > + unsigned long *ptr = NULL; > + void *dest = NULL; > + > + if (kexec_image == NULL) { > + pr_err("Can't update segment: no kexec image loaded.\n"); > + return -EINVAL; > + } > + > + /* > + * kexec_add_buffer rounds up segment sizes to PAGE_SIZE, so > + * we have to do it here as well. > + */ > + memsz = ALIGN(memsz, PAGE_SIZE); > + > + for (i = 0; i < kexec_image->nr_segments; i++) > + /* We only support updating whole segments. */ > + if (load_addr == kexec_image->segment[i].mem && > + memsz == kexec_image->segment[i].memsz) { > + if (kexec_image->segment[i].do_checksum) { > + pr_err("Trying to update non-modifiable segment.\n"); > + return -EINVAL; > + } > + > + break; > + } > + if (i == kexec_image->nr_segments) { > + pr_err("Couldn't find segment to update: 0x%lx, size 0x%lx\n", > + load_addr, memsz); > + return -EINVAL; > + } > + > + for (entry = kexec_image->head; !(entry & IND_DONE) && memsz; > + entry = *ptr++) { > + void *addr = (void *) (entry & PAGE_MASK); > + > + switch (entry & IND_FLAGS) { > + case IND_DESTINATION: > + dest = addr; > + break; > + case IND_INDIRECTION: > + ptr = __va(addr); > + break; > + case IND_SOURCE: > + /* Shouldn't happen, but verify just to be safe. */ > + if (dest == NULL) { > + pr_err("Invalid kexec entries list."); > + return -EINVAL; > + } > + > + if (dest == (void *) load_addr) { > + struct page *page; > + char *ptr; > + size_t uchunk, mchunk; > + > + page = kmap_to_page(addr); > + > + ptr = kmap(page); kmap_atomic() could be used here, and it is appreciably faster. > + ptr += load_addr & ~PAGE_MASK; > + mchunk = min_t(size_t, memsz, > + PAGE_SIZE - (load_addr & ~PAGE_MASK)); > + uchunk = min(bufsz, mchunk); > + memcpy(ptr, buffer, uchunk); > + > + kunmap(page); > + > + bufsz -= uchunk; > + load_addr += mchunk; > + buffer += mchunk; > + memsz -= mchunk; > + } > + dest += PAGE_SIZE; > + } > + > + /* Shouldn't happen, but verify just to be safe. */ > + if (ptr == NULL) { > + pr_err("Invalid kexec entries list."); > + return -EINVAL; > + } > + } > + > + return 0; > +} > + -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 37eea32fdff1..14dda81e3e01 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -259,6 +259,8 @@ extern int kexec_purgatory_get_set_symbol(struct kimage *image, unsigned int size, bool get_value); extern void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name); +int kexec_update_segment(const char *buffer, unsigned long bufsz, + unsigned long load_addr, unsigned long memsz); extern void __crash_kexec(struct pt_regs *); extern void crash_kexec(struct pt_regs *); int kexec_should_crash(struct task_struct *); diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 561675589511..806735201de6 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -721,6 +721,105 @@ static struct page *kimage_alloc_page(struct kimage *image, return page; } +/** + * kexec_update_segment - update the contents of a kimage segment + * @buffer: New contents of the segment. + * @bufsz: @buffer size. + * @load_addr: Segment's physical address in the next kernel. + * @memsz: Segment size. + * + * This function assumes kexec_mutex is held. + * + * Return: 0 on success, negative errno on error. + */ +int kexec_update_segment(const char *buffer, unsigned long bufsz, + unsigned long load_addr, unsigned long memsz) +{ + int i; + unsigned long entry; + unsigned long *ptr = NULL; + void *dest = NULL; + + if (kexec_image == NULL) { + pr_err("Can't update segment: no kexec image loaded.\n"); + return -EINVAL; + } + + /* + * kexec_add_buffer rounds up segment sizes to PAGE_SIZE, so + * we have to do it here as well. + */ + memsz = ALIGN(memsz, PAGE_SIZE); + + for (i = 0; i < kexec_image->nr_segments; i++) + /* We only support updating whole segments. */ + if (load_addr == kexec_image->segment[i].mem && + memsz == kexec_image->segment[i].memsz) { + if (kexec_image->segment[i].do_checksum) { + pr_err("Trying to update non-modifiable segment.\n"); + return -EINVAL; + } + + break; + } + if (i == kexec_image->nr_segments) { + pr_err("Couldn't find segment to update: 0x%lx, size 0x%lx\n", + load_addr, memsz); + return -EINVAL; + } + + for (entry = kexec_image->head; !(entry & IND_DONE) && memsz; + entry = *ptr++) { + void *addr = (void *) (entry & PAGE_MASK); + + switch (entry & IND_FLAGS) { + case IND_DESTINATION: + dest = addr; + break; + case IND_INDIRECTION: + ptr = __va(addr); + break; + case IND_SOURCE: + /* Shouldn't happen, but verify just to be safe. */ + if (dest == NULL) { + pr_err("Invalid kexec entries list."); + return -EINVAL; + } + + if (dest == (void *) load_addr) { + struct page *page; + char *ptr; + size_t uchunk, mchunk; + + page = kmap_to_page(addr); + + ptr = kmap(page); + ptr += load_addr & ~PAGE_MASK; + mchunk = min_t(size_t, memsz, + PAGE_SIZE - (load_addr & ~PAGE_MASK)); + uchunk = min(bufsz, mchunk); + memcpy(ptr, buffer, uchunk); + + kunmap(page); + + bufsz -= uchunk; + load_addr += mchunk; + buffer += mchunk; + memsz -= mchunk; + } + dest += PAGE_SIZE; + } + + /* Shouldn't happen, but verify just to be safe. */ + if (ptr == NULL) { + pr_err("Invalid kexec entries list."); + return -EINVAL; + } + } + + return 0; +} + static int kimage_load_normal_segment(struct kimage *image, struct kexec_segment *segment) {
kexec_update_segment allows a given segment in kexec_image to have its contents updated. This is useful if the current kernel wants to send information to the next kernel that is up-to-date at the time of reboot. Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> --- include/linux/kexec.h | 2 ++ kernel/kexec_core.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 101 insertions(+)