From 91d37211769510ae0b4747045d8f81d3b9dd4278 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 17 Mar 2016 12:47:12 +0100 Subject: [PATCH] s390: add DEBUG_RODATA support git commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings") adds a bogus warning to the console which states that s390 does not support kernel memory protection. This however is not true. We do support that since a couple of years however in a different way than the author of the above named patch expected. To get rid of the misleading message implement the mark_rodata_ro function and emit a message which states the amount of memory which was write protected already earlier. This is the same what parisc currently does. We currently do not support the kernel parameter "rodata=off" which would allow to write to the rodata section again. However since we have this feature since years without any problems there is no reason to add support for this. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/Kconfig | 3 +++ arch/s390/mm/init.c | 10 +++++++--- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 7e3e8a8338d6..f8dea162bd32 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -59,6 +59,9 @@ config PCI_QUIRKS config ARCH_SUPPORTS_UPROBES def_bool y +config DEBUG_RODATA + def_bool y + config S390 def_bool y select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index 73e290337092..c7b0451397d6 100644 --- a/arch/s390/mm/init.c +++ b/arch/s390/mm/init.c @@ -108,6 +108,13 @@ void __init paging_init(void) free_area_init_nodes(max_zone_pfns); } +void mark_rodata_ro(void) +{ + /* Text and rodata are already protected. Nothing to do here. */ + pr_info("Write protecting the kernel read-only data: %luk\n", + ((unsigned long)&_eshared - (unsigned long)&_stext) >> 10); +} + void __init mem_init(void) { if (MACHINE_HAS_TLB_LC) @@ -126,9 +133,6 @@ void __init mem_init(void) setup_zero_pages(); /* Setup zeroed pages. */ mem_init_print_info(NULL); - printk("Write protected kernel read-only data: %#lx - %#lx\n", - (unsigned long)&_stext, - PFN_ALIGN((unsigned long)&_eshared) - 1); } void free_initmem(void) -- 2.20.1