Hi Arnd,
Here is the draft patch. Some questions below.
On 5/24/2017 5:18 AM, Arnd Bergmann wrote:
On Wed, May 24, 2017 at 11:59 AM, Geert Uytterhoeven
<geert@xxxxxxxxxxxxxx> wrote:
On Tue, May 23, 2017 at 11:45 PM, Babu Moger <babu.moger@xxxxxxxxxx> wrote:
Found this problem while enabling queued rwlock on SPARC.
The parameter CONFIG_CPU_BIG_ENDIAN is used to clear the
specific byte in qrwlock structure. Without this parameter,
we clear the wrong byte. Here is the code.
static inline u8 *__qrwlock_write_byte(struct qrwlock *lock)
{
return (u8 *)lock + 3 * IS_BUILTIN(CONFIG_CPU_BIG_ENDIAN);
}
Define CPU_BIG_ENDIAN for SPARC to fix it.
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -92,6 +92,10 @@ config ARCH_DEFCONFIG
config ARCH_PROC_KCORE_TEXT
def_bool y
+config CPU_BIG_ENDIAN
+ bool
+ default y if SPARC
Nice catch!
Traditionally, CPU_BIG_ENDIAN and CPU_LITTLE_ENDIAN were defined only on
architectures that may support both. And it was checked in platform code
and drivers only.
Hence the symbol is lacking from most architectures. Heck, even
architectures that support both may default to one endiannes, and declare
only the symbol for the other endianness:
--- arch/alpha ---
--- arch/arc ---
arch/arc/Kconfig:config CPU_BIG_ENDIAN
--- arch/arm ---
arch/arm/mm/Kconfig:config CPU_BIG_ENDIAN
--- arch/arm64 ---
arch/arm64/Kconfig:config CPU_BIG_ENDIAN
--- arch/blackfin ---
--- arch/c6x ---
arch/c6x/Kconfig:config CPU_BIG_ENDIAN
--- arch/cris ---
--- arch/frv ---
--- arch/h8300 ---
--- arch/hexagon ---
--- arch/ia64 ---
--- arch/Kconfig ---
--- arch/m32r ---
arch/m32r/Kconfig:config CPU_LITTLE_ENDIAN
--- arch/m68k ---
--- arch/metag ---
--- arch/microblaze ---
--- arch/mips ---
arch/mips/Kconfig:config CPU_BIG_ENDIAN
arch/mips/Kconfig:config CPU_LITTLE_ENDIAN
--- arch/mn10300 ---
--- arch/nios2 ---
--- arch/openrisc ---
--- arch/parisc ---
--- arch/powerpc ---
arch/powerpc/platforms/Kconfig.cputype:config CPU_BIG_ENDIAN
arch/powerpc/platforms/Kconfig.cputype:config CPU_LITTLE_ENDIAN
--- arch/s390 ---
arch/s390/Kconfig:config CPU_BIG_ENDIAN
--- arch/score ---
--- arch/sh ---
arch/sh/Kconfig.cpu:config CPU_LITTLE_ENDIAN
arch/sh/Kconfig.cpu:config CPU_BIG_ENDIAN
--- arch/sparc ---
--- arch/tile ---
--- arch/um ---
--- arch/unicore32 ---
--- arch/x86 ---
--- arch/xtensa ---
However, there are already a few users in generic code, which are thus
broken on many platforms:
drivers/of/base.c
drivers/of/fdt.c
drivers/tty/serial/earlycon.c
drivers/tty/serial/serial_core.c
include/asm-generic/qrwlock.h is also generic, but depends on the
architecture to select ARCH_USE_QUEUED_RWLOCKS, which only very few do
(x86, and now sparc).
I guess the time is ripe for adding (both) symbols to all architectures?
Good idea. I think we can do most of this by adding a few lines to
arch/Kconfig:
config CPU_BIG_ENDIAN
bool
config CPU_LITTLE_ENDIAN
def_bool !CPU_BIG_ENDIAN
This way, we only need to add 'select CPU_BIG_ENDIAN' to the
architectures that are always big-endian, and we don't need to
change anything for the ones that have a single 'CPU_BIG_ENDIAN'
option.
The three architectures that have a 'choice' statement (mips, ppc and
sh) will have to convert, and m32r will have to replace the
what to you mean by "(mips, ppc andsh) will have to convert"? Do you
expect any changes here?
option with the opposite one, which could break 'make oldconfig',
but nobody really cares about m32r any more.
Arnd
Here is the proposed draft patch
======================================
---
arch/Kconfig | 6 ++++++
arch/frv/Kconfig | 1 +
arch/h8300/Kconfig | 1 +
arch/m32r/Kconfig | 6 +++---
arch/m68k/Kconfig | 1 +
arch/openrisc/Kconfig | 1 +
arch/parisc/Kconfig | 1 +
arch/s390/Kconfig | 1 +
arch/sparc/Kconfig | 1 +
9 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 6c00e5b..19fcafd 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -867,4 +867,10 @@ config STRICT_MODULE_RWX
config ARCH_WANT_RELAX_ORDER
bool
+config CPU_BIG_ENDIAN
+ bool
+
+config CPU_LITTLE_ENDIAN
+ def_bool !CPU_BIG_ENDIAN
+
source "kernel/gcov/Kconfig"
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index eefd9a4..db258a4 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -16,6 +16,7 @@ config FRV
select OLD_SIGACTION
select HAVE_DEBUG_STACKOVERFLOW
select ARCH_NO_COHERENT_DMA_MMAP
+ select CPU_BIG_ENDIAN
config ZONE_DMA
bool
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index 3ae8525..22ebf28 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -22,6 +22,7 @@ config H8300
select HAVE_ARCH_KGDB
select HAVE_ARCH_HASH
select CPU_NO_EFFICIENT_FFS
+ select CPU_BIG_ENDIAN
config RWSEM_GENERIC_SPINLOCK
def_bool y
diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index 9547446..d57e37b 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -193,9 +193,9 @@ config TIMER_DIVIDE
int "Timer divider (integer)"
default "128"
-config CPU_LITTLE_ENDIAN
- bool "Generate little endian code"
- default n
+config CPU_BIG_ENDIAN
+ bool "Generate big endian code"
+ default y
config MEMORY_START
hex "Physical memory start address (hex)"
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index d140206..b44579b 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -22,6 +22,7 @@ config M68K
select MODULES_USE_ELF_RELA
select OLD_SIGSUSPEND3
select OLD_SIGACTION
+ select CPU_BIG_ENDIAN
config RWSEM_GENERIC_SPINLOCK
bool
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 1e95920..d772983 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -28,6 +28,7 @@ config OPENRISC
select OR1K_PIC
select CPU_NO_EFFICIENT_FFS if !OPENRISC_HAVE_INST_FF1
select NO_BOOTMEM
+ select CPU_BIG_ENDIAN
config MMU
def_bool y
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 531da9e..7a8ec28 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -40,6 +40,7 @@ config PARISC
select GENERIC_CLOCKEVENTS
select ARCH_NO_COHERENT_DMA_MMAP
select CPU_NO_EFFICIENT_FFS
+ select CPU_BIG_ENDIAN
help
The PA-RISC microprocessor is designed by Hewlett-Packard and
used
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index e161faf..169e50b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -177,6 +177,7 @@ config S390
select ARCH_HAS_SCALED_CPUTIME
select VIRT_TO_BUS
select HAVE_NMI
+ select CPU_BIG_ENDIAN
config SCHED_OMIT_FRAME_POINTER
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index c5b5a7b..7a28e8a 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -45,6 +45,7 @@ config SPARC
select CPU_NO_EFFICIENT_FFS
select LOCKDEP_SMALL if LOCKDEP
select ARCH_WANT_RELAX_ORDER
+ select CPU_BIG_ENDIAN
config SPARC32
def_bool !64BIT
--
1.7.1
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