在 2023/12/21 21:14, Baoquan He 写道:
On 12/20/23 at 01:57pm, fuqiang wang wrote:
In memmap_exclude_ranges(), there will exclude elfheader from
crashk_res. In the current x86 architecture code, the elfheader is
always allocated at crashk_res.start. It seems that there won't be a
split a new range. But it depends on the allocation position of
elfheader in crashk_res. To avoid potential out of bounds in future, Set
the array size to 2.
If so, I would suggest to add extra slot for low 1M too in
fill_up_crash_elf_data() lest the low 1M could be changed in the future,
e.g [start, 1M].
Hi Baoquan
This seems to be better for future maintenance. Thank you for your suggestion.
But similar issue will not exist in fill_up_crash_elf_data(). Because
the range to be excluded is [0, 1M], start (0) is special and will not
appear in the middle of existing cmem->ranges[]. I added a comment to
explain it.
Signed-off-by: fuqiang wang <fuqiang.wang@xxxxxxxxxxxx>
---
arch/x86/kernel/crash.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index c92d88680dbf..1c15d0884c90 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -149,6 +149,13 @@ static struct crash_mem *fill_up_crash_elf_data(void)
/*
* Exclusion of crash region and/or crashk_low_res may cause
* another range split. So add extra two slots here.
+ *
+ * Exclusion of low 1M may not cause another range split, because the
+ * range of exclude is [0, 1M] and the condition for splitting a new
+ * region is that the start, end parameters are both in a certain
+ * existing region in cmem and cannot be equal to existing region's
+ * start or end. Obviously, the start of [0, 1M] cannot meet this
+ * condition.
*/
nr_ranges += 2;
cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
@@ -282,9 +289,15 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
struct crash_memmap_data cmd;
struct crash_mem *cmem;
- cmem = vzalloc(struct_size(cmem, ranges, 1));
+ cmem = vzalloc(struct_size(cmem, ranges, 2));
if (!cmem)
return -ENOMEM;
+ cmem->max_nr_ranges = 2;
+
+ /* Exclude some ranges from crashk_res and add rest to memmap */
+ ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
+ if (ret)
+ goto out;
memset(&cmd, 0, sizeof(struct crash_memmap_data));
cmd.params = params;
@@ -320,11 +333,6 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
add_e820_entry(params, &ei);
}
- /* Exclude some ranges from crashk_res and add rest to memmap */
- ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end);
- if (ret)
- goto out;
And you didn't mention moving above code block up in log. I would
suggest keeping it as is because it looks more reasonable to be adjacent
to the following cmem->ranges[] handling.
Yes, baoquan, keeping it as it is may be more coherent.I will post a new patch later.
Thanks
fuqiang
-
for (i = 0; i < cmem->nr_ranges; i++) {
ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
--
2.42.0
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