From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
To: kexec@lists.infradead.org
Cc: linux-security-module@vger.kernel.org,
linux-ima-devel@lists.sourceforge.net,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
x86@kernel.org, Eric Biederman <ebiederm@xmission.com>,
Dave Young <dyoung@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
Baoquan He <bhe@redhat.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Stewart Smith <stewart@linux.vnet.ibm.com>,
Samuel Mendoza-Jonas <sam@mendozajonas.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Eric Richter <erichte@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
Petko Manolov <petkan@mip-labs.com>,
David Laight <David.Laight@ACULAB.COM>,
Balbir Singh <bsingharora@gmail.com>,
Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Subject: [PATCH v2 4/6] kexec_file: Add mechanism to update kexec segments.
Date: Sat, 13 Aug 2016 00:18:23 -0300 [thread overview]
Message-ID: <1471058305-30198-5-git-send-email-bauerman@linux.vnet.ibm.com> (raw)
In-Reply-To: <1471058305-30198-1-git-send-email-bauerman@linux.vnet.ibm.com>
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(+)
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)
{
--
1.9.1
next prev parent reply other threads:[~2016-08-13 3:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-13 3:18 [PATCH v2 0/6] kexec_file: Add buffer hand-over for the next kernel Thiago Jung Bauermann
2016-08-13 3:18 ` [PATCH v2 1/6] kexec_file: Add buffer hand-over support " Thiago Jung Bauermann
2016-08-13 3:18 ` [PATCH v2 2/6] powerpc: " Thiago Jung Bauermann
2016-08-22 3:21 ` Dave Young
2016-08-22 3:38 ` Thiago Jung Bauermann
2016-08-22 7:22 ` Dave Young
2016-08-22 22:21 ` Thiago Jung Bauermann
2016-08-13 3:18 ` [PATCH v2 3/6] kexec_file: Allow skipping checksum calculation for some segments Thiago Jung Bauermann
2016-08-18 9:03 ` Dave Young
2016-08-18 21:09 ` Thiago Jung Bauermann
2016-08-22 3:17 ` Dave Young
2016-08-22 3:25 ` Thiago Jung Bauermann
2016-08-22 3:36 ` Dave Young
2016-08-22 3:45 ` Thiago Jung Bauermann
2016-08-22 22:12 ` Thiago Jung Bauermann
2016-08-13 3:18 ` Thiago Jung Bauermann [this message]
2016-08-15 22:27 ` [PATCH v2 4/6] kexec_file: Add mechanism to update kexec segments Andrew Morton
2016-08-16 17:00 ` Thiago Jung Bauermann
2016-08-13 3:18 ` [PATCH v2 5/6] kexec: Share logic to copy segment page contents Thiago Jung Bauermann
2016-08-13 3:18 ` [PATCH v2 6/6] IMA: Demonstration code for kexec buffer passing Thiago Jung Bauermann
2016-08-17 2:52 ` [PATCH v2 0/6] kexec_file: Add buffer hand-over for the next kernel Dave Young
2016-08-17 4:58 ` Thiago Jung Bauermann
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