32-bit userspace ABI: introduce ARCH_32BIT_OFF_T config option

All new 32-bit architectures should have 64-bit userspace off_t type, but
existing architectures has 32-bit ones.

To enforce the rule, new config option is added to arch/Kconfig that defaults
ARCH_32BIT_OFF_T to be disabled for new 32-bit architectures. All existing
32-bit architectures enable it explicitly.

New option affects force_o_largefile() behaviour. Namely, if userspace
off_t is 64-bits long, we have no reason to reject user to open big files.

Note that even if architectures has only 64-bit off_t in the kernel
(arc, c6x, h8300, hexagon, nios2, openrisc, and unicore32),
a libc may use 32-bit off_t, and therefore want to limit the file size
to 4GB unless specified differently in the open flags.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Yury Norov <ynorov@marvell.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 46db715a7f42..cd5f443865ec 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -276,6 +276,16 @@ config ARCH_THREAD_STACK_ALLOCATOR
 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
         bool
 
+config ARCH_32BIT_OFF_T
+        bool
+        depends on !64BIT
+        help
+          All new 32-bit architectures should have 64-bit off_t type on
+          userspace side which corresponds to the loff_t kernel type. This
+          is the requirement for modern ABIs. Some existing architectures
+          still support 32-bit off_t. This option is enabled for all such
+          architectures explicitly.
+
 config HAVE_REGS_AND_STACK_ACCESS_API
         bool
         help