From 7c3eaaa3917d8b5491f58ea263bf6e719fd3155f Mon Sep 17 00:00:00 2001 From: Philipp Rudo Date: Tue, 17 Oct 2017 12:28:08 +0200 Subject: s390/kexec: Fix checksum validation return code for kdump Before kexec boots to a crash kernel it checks whether the image in memory changed after load. This is done by the function kdump_csum_valid, which returns true, i.e. an int != 0, on success and 0 otherwise. In other words when kdump_csum_valid returns an error code it means that the validation succeeded. This is not only counterintuitive but also produces the wrong result if the kernel was build without CONFIG_CRASH_DUMP. Fix this by making kdump_csum_valid return a bool. Signed-off-by: Philipp Rudo Acked-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/machine_kexec.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/s390/kernel/machine_kexec.c') diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c index 3d0b14afa232..51e8c63705a9 100644 --- a/arch/s390/kernel/machine_kexec.c +++ b/arch/s390/kernel/machine_kexec.c @@ -144,7 +144,7 @@ static noinline void __machine_kdump(void *image) /* * Check if kdump checksums are valid: We call purgatory with parameter "0" */ -static int kdump_csum_valid(struct kimage *image) +static bool kdump_csum_valid(struct kimage *image) { #ifdef CONFIG_CRASH_DUMP int (*start_kdump)(int) = (void *)image->start; @@ -153,9 +153,9 @@ static int kdump_csum_valid(struct kimage *image) __arch_local_irq_stnsm(0xfb); /* disable DAT */ rc = start_kdump(0); __arch_local_irq_stosm(0x04); /* enable DAT */ - return rc ? 0 : -EINVAL; + return rc == 0; #else - return -EINVAL; + return false; #endif } -- cgit v1.2.3 From ad3bc0ac1d2ed311ef3a9d6f2849948433a9f338 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 12 Oct 2017 13:24:45 +0200 Subject: s390/ctl_reg: use decoding unions in update_cr_regs Add a decoding union for the bits in control registers 2 and use 'union ctlreg0' and 'union ctlreg2' in update_cr_regs to improve readability. Reviewed-by: Heiko Carstens Reviewed-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/machine_kexec.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'arch/s390/kernel/machine_kexec.c') diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c index 51e8c63705a9..e94421678b13 100644 --- a/arch/s390/kernel/machine_kexec.c +++ b/arch/s390/kernel/machine_kexec.c @@ -105,7 +105,7 @@ static void __do_machine_kdump(void *image) static noinline void __machine_kdump(void *image) { struct mcesa *mcesa; - unsigned long cr2_old, cr2_new; + union ctlreg2 cr2_old, cr2_new; int this_cpu, cpu; lgr_info_log(); @@ -122,11 +122,12 @@ static noinline void __machine_kdump(void *image) if (MACHINE_HAS_VX) save_vx_regs((__vector128 *) mcesa->vector_save_area); if (MACHINE_HAS_GS) { - __ctl_store(cr2_old, 2, 2); - cr2_new = cr2_old | (1UL << 4); - __ctl_load(cr2_new, 2, 2); + __ctl_store(cr2_old.val, 2, 2); + cr2_new = cr2_old; + cr2_new.gse = 1; + __ctl_load(cr2_new.val, 2, 2); save_gs_cb((struct gs_cb *) mcesa->guarded_storage_save_area); - __ctl_load(cr2_old, 2, 2); + __ctl_load(cr2_old.val, 2, 2); } /* * To create a good backchain for this CPU in the dump store_status -- cgit v1.2.3 From 978fa72e82e375764e6e31e7a721408c5186918f Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 2 Nov 2017 12:51:45 +0100 Subject: s390: remove named saved segment support Remove the support to create a z/VM named saved segment (NSS). This feature is not supported since quite a while in favour of jump labels, function tracing and (now) CPU alternatives. All of these features require to write to the kernel text section which is not possible if the kernel is contained within an NSS. Given that memory savings are minimal if kernel images are shared and in addition updates of shared images are painful, the NSS feature can be removed. Reviewed-by: Hendrik Brueckner Signed-off-by: Heiko Carstens --- arch/s390/kernel/machine_kexec.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'arch/s390/kernel/machine_kexec.c') diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c index e94421678b13..c72e551e5951 100644 --- a/arch/s390/kernel/machine_kexec.c +++ b/arch/s390/kernel/machine_kexec.c @@ -219,10 +219,6 @@ int machine_kexec_prepare(struct kimage *image) { void *reboot_code_buffer; - /* Can't replace kernel image since it is read-only. */ - if (ipl_flags & IPL_NSS_VALID) - return -EOPNOTSUPP; - if (image->type == KEXEC_TYPE_CRASH) return machine_kexec_prepare_kdump(); -- cgit v1.2.3 From d0e810eeb3d326978f248b8f0233a2f30f58c72d Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 9 Nov 2017 23:00:14 +0100 Subject: s390/noexec: execute kexec datamover without DAT Rebooting into a new kernel with kexec fails (system dies) if tried on a machine that has no-execute support. Reason for this is that the so called datamover code gets executed with DAT on (MMU is active) and the page that contains the datamover is marked as non-executable. Therefore when branching into the datamover an unexpected program check happens and afterwards the machine is dead. This can be simply avoided by disabling DAT, which also disables any no-execute checks, just before the datamover gets executed. In fact the first thing done by the datamover is to disable DAT. The code in the datamover that disables DAT can be removed as well. Thanks to Michael Holzheu and Gerald Schaefer for tracking this down. Reviewed-by: Michael Holzheu Reviewed-by: Philipp Rudo Cc: Gerald Schaefer Cc: Martin Schwidefsky Fixes: 57d7f939e7bd ("s390: add no-execute support") Cc: # v4.11+ Signed-off-by: Heiko Carstens --- arch/s390/kernel/machine_kexec.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/s390/kernel/machine_kexec.c') diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c index c72e551e5951..4d91761f1177 100644 --- a/arch/s390/kernel/machine_kexec.c +++ b/arch/s390/kernel/machine_kexec.c @@ -265,6 +265,7 @@ static void __do_machine_kexec(void *data) s390_reset_system(); data_mover = (relocate_kernel_t) page_to_phys(image->control_code_page); + __arch_local_irq_stnsm(0xfb); /* disable DAT - avoid no-execute */ /* Call the moving routine */ (*data_mover)(&image->head, image->start); -- cgit v1.2.3