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Subject[PATCH v2 17/20] vmcore: check if vmcore objects satify mmap()'s page-size boundary requirement
Date
If there's some vmcore object that doesn't satisfy page-size boundary
requirement, remap_pfn_range() fails to remap it to user-space.

Objects that posisbly don't satisfy the requirement are ELF note
segments only. The memory chunks corresponding to PT_LOAD entries are
guaranteed to satisfy page-size boundary requirement by the copy from
old memory to buffer in 2nd kernel done in later patch.

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
---

fs/proc/vmcore.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index e432946..5582aaa 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -38,6 +38,8 @@ static u64 vmcore_size;

static struct proc_dir_entry *proc_vmcore = NULL;

+static bool support_mmap_vmcore;
+
/*
* Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
* The called function has to take care of module refcounting.
@@ -897,6 +899,7 @@ static int __init parse_crash_elf_headers(void)
static int __init vmcore_init(void)
{
int rc = 0;
+ struct vmcore *m;

/* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
if (!(is_vmcore_usable()))
@@ -907,6 +910,25 @@ static int __init vmcore_init(void)
return rc;
}

+ /* If some object doesn't satisfy PAGE_SIZE boundary
+ * requirement, mmap_vmcore() is not exported to
+ * user-space. */
+ support_mmap_vmcore = true;
+ list_for_each_entry(m, &vmcore_list, list) {
+ u64 paddr;
+
+ if (m->flag & MEM_TYPE_CURRENT_KERNEL)
+ paddr = (u64)__pa(m->buf);
+ else
+ paddr = m->paddr;
+
+ if ((m->offset & ~PAGE_MASK) || (paddr & ~PAGE_MASK)
+ || (m->size & ~PAGE_MASK)) {
+ support_mmap_vmcore = false;
+ break;
+ }
+ }
+
proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
if (proc_vmcore)
proc_vmcore->size = vmcore_size;


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