s390/setup: preserve memory at OLDMEM_BASE and OLDMEM_SIZE

BugLink: https://bugs.launchpad.net/bugs/1987451
[ Upstream commit 6b4b54c7ca347bcb4aa7a3cc01aa16e84ac7fbe4 ]

We need to preserve the values at OLDMEM_BASE and OLDMEM_SIZE which are
used by zgetdump in case when kdump crashes. In that case zgetdump will
attempt to read OLDMEM_BASE and OLDMEM_SIZE in order to find out where
the memory range [0 - OLDMEM_SIZE] belonging to the production kernel is.

Fixes: f1a546947431 ("s390/setup: don't reserve memory that occupied decompressor's head")
Cc: stable@vger.kernel.org # 5.15+
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 8992f64a4ffe91a645376f2fc2838724065dc85b..2fb23881727fe37314f83b18cc7c1b5ef451ef9c 100644 (file)
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -799,6 +799,8 @@ static void __init check_initrd(void)
 static void __init reserve_kernel(void)
 {
        memblock_reserve(0, STARTUP_NORMAL_OFFSET);
+       memblock_reserve(OLDMEM_BASE, sizeof(unsigned long));
+       memblock_reserve(OLDMEM_SIZE, sizeof(unsigned long));
        memblock_reserve(__amode31_base, __eamode31 - __samode31);
        memblock_reserve(__pa(sclp_early_sccb), EXT_SCCB_READ_SCP);
        memblock_reserve(__pa(_stext), _end - _stext);