On 08/07/2018 02:12 AM, Hari Bathini wrote:
> With dynamic memory allocation support for crash memory ranges array,
> there is no hard limit on the no. of crash memory ranges kernel could
> export, but program headers count could overflow in the /proc/vmcore
> ELF file while exporting each memory range as PT_LOAD segment. Reduce
> the likelihood of a such scenario, by folding adjacent crash memory
> ranges which minimizes the total number of PT_LOAD segments.
>
> Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
> ---
> arch/powerpc/kernel/fadump.c | 45
> ++++++++++++++++++++++++++++++++++--------
> 1 file changed, 36 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index 2ec5704..cd0c555 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -908,22 +908,41 @@ static int allocate_crash_memory_ranges(void)
> static inline int fadump_add_crash_memory(unsigned long long base,
> unsigned long long end)
> {
> + u64 start, size;
> + bool is_adjacent = false;
> +
> if (base == end)
> return 0;
>
> - if (crash_mem_ranges == max_crash_mem_ranges) {
> - int ret;
> + /*
> + * Fold adjacent memory ranges to bring down the memory ranges/
> + * PT_LOAD segments count.
> + */
> + if (crash_mem_ranges) {
> + start = crash_memory_ranges[crash_mem_ranges-1].base;
> + size = crash_memory_ranges[crash_mem_ranges-1].size;
>
> - ret = allocate_crash_memory_ranges();
> - if (ret)
> - return ret;
> + if ((start + size) == base)
> + is_adjacent = true;
> + }
> + if (!is_adjacent) {
> + /* resize the array on reaching the limit */
> + if (crash_mem_ranges == max_crash_mem_ranges) {
> + int ret;
> +
> + ret = allocate_crash_memory_ranges();
> + if (ret)
> + return ret;
> + }
> +
> + start = base;
> + crash_memory_ranges[crash_mem_ranges].base = start;
> + crash_mem_ranges++;
> }
>
> + crash_memory_ranges[crash_mem_ranges-1].size = (end - start);
> pr_debug("crash_memory_range[%d] [%#016llx-%#016llx], %#llx bytes\n",
> - crash_mem_ranges, base, end - 1, (end - base));
> - crash_memory_ranges[crash_mem_ranges].base = base;
> - crash_memory_ranges[crash_mem_ranges].size = end - base;
> - crash_mem_ranges++;
> + (crash_mem_ranges - 1), start, end - 1, (end - start));
> return 0;
> }
>
> @@ -999,6 +1018,14 @@ static int fadump_setup_crash_memory_ranges(void)
>
> pr_debug("Setup crash memory ranges.\n");
> crash_mem_ranges = 0;
> +
> + /* allocate memory for crash memory ranges for the first time */
> + if (!max_crash_mem_ranges) {
> + ret = allocate_crash_memory_ranges();
> + if (ret)
> + return ret;
> + }
> +
I see that the check for (!is_adjacent) in first hunk already handles
the first time allocation. Do we need this ?
Rest looks fine to me.
Reviewed-by: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com>
Thanks,
-Mahesh.
> /*
> * add the first memory chunk (RMA_START through boot_memory_size) as
> * a separate memory chunk. The reason is, at the time crash firmware
>
