[RFC Patch 1/2] kexec: show memory info in /proc/iomem

Amerigo Wang
2009-08-11T10:39:22Z

This patch implements showing kexec memory area via /proc/iomem.
For example, with this patch we can see:

# cat /proc/iomem
...
00100000-7ffeffff : System RAM
01000000-012e1424 : Kernel code
012e1425-015f1aff : Kernel data
0166b000-01b4b88f : Kernel bss
02000000-083fffff : Crash kernel
02000000-028fffff : Used
02900000-083fffff : Unused
...

So that user can know how much memory the kernel uses for crash kernel.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <andi@firstfloor.org>

---
diff --git a/kernel/kexec.c b/kernel/kexec.c
index f336e21..01673ad 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -931,6 +931,8 @@ static int kimage_load_segment(struct kimage *image,
*/
struct kimage *kexec_image;
struct kimage *kexec_crash_image;
+struct resource *kexec_res = NULL;
+struct resource *kexec_free_res = NULL;

static DEFINE_MUTEX(kexec_mutex);

@@ -939,6 +941,8 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
{
struct kimage **dest_image, *image;
int result;
+ unsigned long kexec_start = crashk_res.start;
+ unsigned long kexec_end = kexec_start;

/* We only trust the superuser with rebooting the system. */
if (!capable(CAP_SYS_BOOT))
@@ -994,6 +998,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
kimage_free(xchg(&kexec_crash_image, NULL));
result = kimage_crash_alloc(&image, entry,
nr_segments, segments);
+ kexec_end += KEXEC_CONTROL_PAGE_SIZE;
}
if (result)
goto out;
@@ -1008,6 +1013,42 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
result = kimage_load_segment(image, &image->segment[i]);
if (result)
goto out;
+ if (flags & KEXEC_ON_CRASH)
+ kexec_end += image->segment[i].memsz;
+ }
+ if (flags & KEXEC_ON_CRASH) {
+ if (kexec_res) {
+ release_resource(kexec_res);
+ release_resource(kexec_free_res);
+ kfree(kexec_res);
+ kfree(kexec_free_res);
+ }
+ kexec_res = kzalloc(sizeof(*kexec_res), GFP_KERNEL);
+ if (!kexec_res) {
+ result = -ENOMEM;
+ goto out;
+ }
+ kexec_free_res = kzalloc(sizeof(*kexec_free_res), GFP_KERNEL);
+ if (!kexec_free_res) {
+ result = -ENOMEM;
+ goto out_free;
+ }
+ kexec_res->name = "Used";
+ kexec_res->start = kexec_start;
+ kexec_res->end = roundup(kexec_end, 1<<20) - 1;
+ kexec_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
+ if (insert_resource(&crashk_res, kexec_res)) {
+ result = -EBUSY;
+ goto out_free;
+ }
+ kexec_free_res->name = "Unused";
+ kexec_free_res->start = kexec_res->end + 1;
+ kexec_free_res->end = crashk_res.end;
+ kexec_free_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
+ if (insert_resource(&crashk_res, kexec_free_res)) {
+ result = -EBUSY;
+ goto out_release;
+ }
}
kimage_terminate(image);
}
@@ -1019,6 +1060,13 @@ out:
kimage_free(image);

return result;
+
+out_free:
+ kfree(kexec_free_res);
+ kfree(kexec_res);
+out_release:
+ release_resource(kexec_res);
+ goto out;
}

#ifdef CONFIG_COMPAT