[PATCH v4 1/6] libnvdimm/namespace: Make namespace size validation arch dependent

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

The page size used to map the namespace is arch dependent. For example
architectures like ppc64 use 16MB page size for direct-mapping. If the namespace
size is not aligned to the mapping page size, users can observe kernel crash
during namespace init and destroy.

This is due to kernel doing partial map/unmap of the resource range

BUG: Unable to handle kernel data access at 0xc001000406000000
Faulting instruction address: 0xc000000000090790
NIP [c000000000090790] arch_add_memory+0xc0/0x130
LR [c000000000090744] arch_add_memory+0x74/0x130
Call Trace:
 arch_add_memory+0x74/0x130 (unreliable)
 memremap_pages+0x74c/0xa30
 devm_memremap_pages+0x3c/0xa0
 pmem_attach_disk+0x188/0x770
 nvdimm_bus_probe+0xd8/0x470
 really_probe+0x148/0x570
 driver_probe_device+0x19c/0x1d0
 device_driver_attach+0xcc/0x100
 bind_store+0x134/0x1c0
 drv_attr_store+0x44/0x60
 sysfs_kf_write+0x74/0xc0
 kernfs_fop_write+0x1b4/0x290
 __vfs_write+0x3c/0x70
 vfs_write+0xd0/0x260
 ksys_write+0xdc/0x130
 system_call+0x5c/0x68

Kernel should also ensure that namespace size is also mulitple of subsection size.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/arm64/mm/flush.c     | 6 ++++++
 arch/powerpc/lib/pmem.c   | 9 +++++++++
 arch/x86/mm/pageattr.c    | 7 +++++++
 include/linux/libnvdimm.h | 1 +
 4 files changed, 23 insertions(+)

diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
index ac485163a4a7..95cb5538bc6e 100644
--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -91,4 +91,10 @@ void arch_invalidate_pmem(void *addr, size_t size)
 	__inval_dcache_area(addr, size);
 }
 EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
+
+unsigned long arch_namespace_map_size(void)
+{
+	return PAGE_SIZE;
+}
+EXPORT_SYMBOL_GPL(arch_namespace_map_size);
 #endif
diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c
index 0666a8d29596..63dca24e4a18 100644
--- a/arch/powerpc/lib/pmem.c
+++ b/arch/powerpc/lib/pmem.c
@@ -26,6 +26,15 @@ void arch_invalidate_pmem(void *addr, size_t size)
 }
 EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
 
+unsigned long arch_namespace_map_size(void)
+{
+	if (radix_enabled())
+		return PAGE_SIZE;
+	return (1UL << mmu_psize_defs[mmu_linear_psize].shift);
+
+}
+EXPORT_SYMBOL_GPL(arch_namespace_map_size);
+
 /*
  * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols
  */
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 1b99ad05b117..d78b5082f376 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -310,6 +310,13 @@ void arch_invalidate_pmem(void *addr, size_t size)
 }
 EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
 
+unsigned long arch_namespace_map_size(void)
+{
+	return PAGE_SIZE;
+}
+EXPORT_SYMBOL_GPL(arch_namespace_map_size);
+
+
 static void __cpa_flush_all(void *arg)
 {
 	unsigned long cache = (unsigned long)arg;
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index 9df091bd30ba..a3476dbd2656 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size)
 }
 #endif
 
+unsigned long arch_namespace_map_size(void);
 #endif /* __LIBNVDIMM_H__ */
-- 
2.24.1
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