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crash_core: fix and simplify the logic of crash_exclude_mem_range()

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The purpose of crash_exclude_mem_range() is to remove all memory ranges
that overlap with [mstart-mend].  However, the current logic only removes
the first overlapping memory range.

Commit a2e9a95d21 ("kexec: Improve & fix crash_exclude_mem_range() to
handle overlapping ranges") attempted to address this issue, but it did
not fix all error cases.

Let's fix and simplify the logic of crash_exclude_mem_range().

Link: https://lkml.kernel.org/r/20240102144905.110047-4-ytcoode@gmail.com
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yuntao Wang 2024-01-02 22:49:05 +08:00 committed by Andrew Morton
parent 61bb219f9d
commit 6dff315972
1 changed files with 29 additions and 51 deletions
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80
kernel/crash_core.c
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@ -566,9 +566,8 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart, unsigned long long mend)
{
int i, j;
int i;
unsigned long long start, end, p_start, p_end;
struct range temp_range = {0, 0};
for (i = 0; i < mem->nr_ranges; i++) {
start = mem->ranges[i].start;
@ -576,72 +575,51 @@ int crash_exclude_mem_range(struct crash_mem *mem,
p_start = mstart;
p_end = mend;
if (mstart > end || mend < start)
if (p_start > end)
continue;
/*
* Because the memory ranges in mem->ranges are stored in
* ascending order, when we detect `p_end < start`, we can
* immediately exit the for loop, as the subsequent memory
* ranges will definitely be outside the range we are looking
* for.
*/
if (p_end < start)
break;
/* Truncate any area outside of range */
if (mstart < start)
if (p_start < start)
p_start = start;
if (mend > end)
if (p_end > end)
p_end = end;
/* Found completely overlapping range */
if (p_start == start && p_end == end) {
mem->ranges[i].start = 0;
mem->ranges[i].end = 0;
if (i < mem->nr_ranges - 1) {
/* Shift rest of the ranges to left */
for (j = i; j < mem->nr_ranges - 1; j++) {
mem->ranges[j].start =
mem->ranges[j+1].start;
mem->ranges[j].end =
mem->ranges[j+1].end;
}
/*
* Continue to check if there are another overlapping ranges
* from the current position because of shifting the above
* mem ranges.
*/
i--;
mem->nr_ranges--;
continue;
}
memmove(&mem->ranges[i], &mem->ranges[i + 1],
(mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i]));
i--;
mem->nr_ranges--;
return 0;
}
if (p_start > start && p_end < end) {
} else if (p_start > start && p_end < end) {
/* Split original range */
if (mem->nr_ranges >= mem->max_nr_ranges)
return -ENOMEM;
memmove(&mem->ranges[i + 2], &mem->ranges[i + 1],
(mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i]));
mem->ranges[i].end = p_start - 1;
temp_range.start = p_end + 1;
temp_range.end = end;
mem->ranges[i + 1].start = p_end + 1;
mem->ranges[i + 1].end = end;
i++;
mem->nr_ranges++;
} else if (p_start != start)
mem->ranges[i].end = p_start - 1;
else
mem->ranges[i].start = p_end + 1;
break;
}
/* If a split happened, add the split to array */
if (!temp_range.end)
return 0;
/* Split happened */
if (i == mem->max_nr_ranges - 1)
return -ENOMEM;
/* Location where new range should go */
j = i + 1;
if (j < mem->nr_ranges) {
/* Move over all ranges one slot towards the end */
for (i = mem->nr_ranges - 1; i >= j; i--)
mem->ranges[i + 1] = mem->ranges[i];
}
mem->ranges[j].start = temp_range.start;
mem->ranges[j].end = temp_range.end;
mem->nr_ranges++;
return 0;
}