[PATCH 4.4 01/53] sparc: Fix -Wstringop-overflow warning

Greg Kroah-Hartman
2017-06-05T17:30:37Z

From: Orlando Arias <oarias@knights.ucf.edu>

[ Upstream commit deba804c90642c8ed0f15ac1083663976d578f54 ]

Greetings,

GCC 7 introduced the -Wstringop-overflow flag to detect buffer overflows
in calls to string handling functions [1][2]. Due to the way
``empty_zero_page'' is declared in arch/sparc/include/setup.h, this
causes a warning to trigger at compile time in the function mem_init(),
which is subsequently converted to an error. The ensuing patch fixes
this issue and aligns the declaration of empty_zero_page to that of
other architectures. Thank you.

Cheers,
Orlando.

[1] https://gcc.gnu.org/ml/gcc-patches/2016-10/msg02308.html
[2] https://gcc.gnu.org/gcc-7/changes.html

Signed-off-by: Orlando Arias <oarias@knights.ucf.edu>

--------------------------------------------------------------------------------
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/sparc/include/asm/pgtable_32.h | 4 ++--
arch/sparc/include/asm/setup.h | 2 +-
arch/sparc/mm/init_32.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/sparc/include/asm/pgtable_32.h
+++ b/arch/sparc/include/asm/pgtable_32.h
@@ -91,9 +91,9 @@ extern unsigned long pfn_base;
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
-extern unsigned long empty_zero_page;
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];

-#define ZERO_PAGE(vaddr) (virt_to_page(&empty_zero_page))
+#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))

/*
* In general all page table modifications should use the V8 atomic
--- a/arch/sparc/include/asm/setup.h
+++ b/arch/sparc/include/asm/setup.h
@@ -16,7 +16,7 @@ extern char reboot_command[];
*/
extern unsigned char boot_cpu_id;

-extern unsigned long empty_zero_page;
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];

extern int serial_console;
static inline int con_is_present(void)
--- a/arch/sparc/mm/init_32.c
+++ b/arch/sparc/mm/init_32.c
@@ -301,7 +301,7 @@ void __init mem_init(void)

/* Saves us work later. */
- memset((void *)&empty_zero_page, 0, PAGE_SIZE);
+ memset((void *)empty_zero_page, 0, PAGE_SIZE);

i = last_valid_pfn >> ((20 - PAGE_SHIFT) + 5);
i += 1;