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authorAlexander Gordeev <agordeev@linux.ibm.com>2023-04-03 08:44:40 +0200
committerVasily Gorbik <gor@linux.ibm.com>2023-04-19 17:24:16 +0200
commit2d1b21eceaf0765d60b543b2b8e26c2f55517259 (patch)
tree1de582fe2a05fc11880b4365c886b1d3be288058 /arch/s390/kernel/machine_kexec.c
parent82caf7aba107dbc0e70c330786bed9961a098ab0 (diff)
s390/kdump: remove nodat stack restriction for calling nodat functions
To allow calling of DAT-off code from kernel the stack needs to be switched to nodat_stack (or other stack mapped as 1:1). Before call_nodat() macro was introduced that was necessary to provide the very same memory address for STNSM and STOSM instructions. If the kernel would stay on a random stack (e.g. a virtually mapped one) then a virtual address provided for STNSM instruction could differ from the physical address needed for the corresponding STOSM instruction. After call_nodat() macro is introduced the kernel stack does not need to be mapped 1:1 anymore, since the macro stores the physical memory address of return PSW in a register before entering DAT-off mode. This way the return LPSWE instruction is able to pick the correct memory location and restore the DAT-on mode. That however might fail in case the 16-byte return PSW happened to cross page boundary: PSW mask and PSW address could end up in two separate non-contiguous physical pages. Align the return PSW on 16-byte boundary so it always fits into a single physical page. As result any stack (including the virtually mapped one) could be used for calling DAT-off code and prior switching to nodat_stack becomes unnecessary. Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/machine_kexec.c')
-rw-r--r--arch/s390/kernel/machine_kexec.c13
1 files changed, 2 insertions, 11 deletions
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index f5d8abf3b4fb..6d9276c096a6 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -112,13 +112,6 @@ static noinline void __machine_kdump(void *image)
store_status(__do_machine_kdump, image);
}
-static int do_start_kdump(struct kimage *image)
-{
- purgatory_t purgatory = (purgatory_t)image->start;
-
- return call_nodat(1, int, purgatory, int, 0);
-}
-
#endif /* CONFIG_CRASH_DUMP */
/*
@@ -127,12 +120,10 @@ static int do_start_kdump(struct kimage *image)
static bool kdump_csum_valid(struct kimage *image)
{
#ifdef CONFIG_CRASH_DUMP
+ purgatory_t purgatory = (purgatory_t)image->start;
int rc;
- preempt_disable();
- rc = call_on_stack(1, S390_lowcore.nodat_stack, int, do_start_kdump,
- struct kimage *, image);
- preempt_enable();
+ rc = call_nodat(1, int, purgatory, int, 0);
return rc == 0;
#else
return false;