From: bob picco <bpicco@xxxxxxxxxx>
This patch adds support to enable STRICT_DEVMEM for sparc64. By selecting the
new config option you enable this feature.
CC: Sam Ravnborg <sam@xxxxxxxxxxxx>
Signed-off-by: Bob Picco <bob.picco@xxxxxxxxxx>
---
arch/sparc/Kconfig.debug | 8 ++++++++
arch/sparc/include/asm/page_64.h | 1 +
arch/sparc/mm/init_64.c | 11 +++++++++++
3 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/arch/sparc/Kconfig.debug b/arch/sparc/Kconfig.debug
index 6db35fb..92f2388 100644
--- a/arch/sparc/Kconfig.debug
+++ b/arch/sparc/Kconfig.debug
@@ -6,6 +6,14 @@ config TRACE_IRQFLAGS_SUPPORT
source "lib/Kconfig.debug"
+config STRICT_DEVMEM
+ bool "Filter access to /dev/mem"
+ ---help---
+ If this option is disabled, you allow userspace (root) access to all
+ of memory, including kernel and userspace memory. Accidental
+ access to this is obviously disastrous, but specific access can
+ be used by people debugging the kernel.
+
config DEBUG_DCFLUSH
bool "D-cache flush debugging"
depends on SPARC64 && DEBUG_KERNEL
diff --git a/arch/sparc/include/asm/page_64.h b/arch/sparc/include/asm/page_64.h
index aac53fc..e54ee50 100644
--- a/arch/sparc/include/asm/page_64.h
+++ b/arch/sparc/include/asm/page_64.h
@@ -36,6 +36,7 @@ extern void hugetlb_setup(struct pt_regs *regs);
#define WANT_PAGE_VIRTUAL
+extern int devmem_is_allowed(unsigned long pagenr);
extern void _clear_page(void *page);
#define clear_page(X) _clear_page((void *)(X))
struct page;
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index a4a9b69..0a38a42 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -2759,3 +2759,14 @@ static int __init report_memory(void)
return 0;
}
device_initcall(report_memory);
+
+#ifdef CONFIG_STRICT_DEVMEM
+int devmem_is_allowed(unsigned long pagenr)
+{
+ unsigned long phys_addr = pagenr << PAGE_SHIFT;
+ unsigned long virt_addr = (unsigned long) __va(phys_addr);
+ int rc = kern_addr_valid(virt_addr);
+
+ return rc;
+}
+#endif /* CONFIG_STRICT_DEVMEM */
--
1.7.1
--
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