From: Hari Bathini hbathini@linux.ibm.com
[ Upstream commit 15eb77f873255cf9f4d703b63cfbd23c46579654 ]
Boot memory area is setup as separate PT_LOAD segment in the vmcore as it is moved by f/w, on crash, to a destination address provided by the kernel. Having separate PT_LOAD segment helps in handling the different physical address and offset for boot memory area in the vmcore.
Commit ced1bf52f477 ("powerpc/fadump: merge adjacent memory ranges to reduce PT_LOAD segements") inadvertly broke this pre-condition for cases where some of the first kernel memory is available adjacent to boot memory area. This scenario is rare but possible when memory for fadump could not be reserved adjacent to boot memory area owing to memory hole or such. Reading memory from a vmcore exported in such scenario provides incorrect data. Fix it by ensuring no other region is folded into boot memory area.
Fixes: ced1bf52f477 ("powerpc/fadump: merge adjacent memory ranges to reduce PT_LOAD segements") Signed-off-by: Hari Bathini hbathini@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220406093839.206608-2-hbathini@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kernel/fadump.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index 0455dc1b2797..69d64f406204 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -835,7 +835,6 @@ static int fadump_alloc_mem_ranges(struct fadump_mrange_info *mrange_info) sizeof(struct fadump_memory_range)); return 0; } - static inline int fadump_add_mem_range(struct fadump_mrange_info *mrange_info, u64 base, u64 end) { @@ -854,7 +853,12 @@ static inline int fadump_add_mem_range(struct fadump_mrange_info *mrange_info, start = mem_ranges[mrange_info->mem_range_cnt - 1].base; size = mem_ranges[mrange_info->mem_range_cnt - 1].size;
- if ((start + size) == base) + /* + * Boot memory area needs separate PT_LOAD segment(s) as it + * is moved to a different location at the time of crash. + * So, fold only if the region is not boot memory area. + */ + if ((start + size) == base && start >= fw_dump.boot_mem_top) is_adjacent = true; } if (!is_adjacent) {