arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to `__bad_cmpxchg' follow
The arm builds failed on Linux next with gcc-13 and clang-18.
Config: arm imx_v6_v7_defconfig - failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
Build log: ----- arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_trc_cmpxchg_need_qs': update.c:(.text+0x348): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_read_unlock_trace_special': update.c:(.text+0x41c): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_read_check_handler': update.c:(.text+0x4b0): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_inspect_reader': update.c:(.text+0x1518): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: update.c:(.text+0x1548): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to `__bad_cmpxchg' follow make[3]: *** [/builds/linux/scripts/Makefile.vmlinux:34: vmlinux] Error 1
metadata: git_describe: next-20240529 git_repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next git_short_log: 9d99040b1bc8 ("Add linux-next specific files for 20240529") job_url: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/builds/2h944W0LTb...
Links: - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240529/tes... - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20240529/tes...
-- Linaro LKFT https://lkft.linaro.org
On Thu, May 30, 2024 at 05:50:52PM +0530, Naresh Kamboju wrote:
The arm builds failed on Linux next with gcc-13 and clang-18.
Config: arm imx_v6_v7_defconfig - failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
Build log:
arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_trc_cmpxchg_need_qs': update.c:(.text+0x348): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_read_unlock_trace_special': update.c:(.text+0x41c): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_read_check_handler': update.c:(.text+0x4b0): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_inspect_reader': update.c:(.text+0x1518): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: update.c:(.text+0x1548): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to `__bad_cmpxchg' follow make[3]: *** [/builds/linux/scripts/Makefile.vmlinux:34: vmlinux] Error 1
You get a reference to __bad_cmpxchg() when someone uses cmpxchg() on a datatype that there are no CPU instructions to perform the atomic compare-and-exchange.
As we support 8-bit, 16-bit and 32-bit, I would expect that we're now seeing cmpxchg() being used on 64-bit values, which are unsupportable on 32-bit Arm.
On Thu, May 30, 2024, at 14:26, Russell King (Oracle) wrote:
On Thu, May 30, 2024 at 05:50:52PM +0530, Naresh Kamboju wrote:
The arm builds failed on Linux next with gcc-13 and clang-18.
Config: arm imx_v6_v7_defconfig - failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
Build log:
arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_trc_cmpxchg_need_qs': update.c:(.text+0x348): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_read_unlock_trace_special': update.c:(.text+0x41c): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_read_check_handler': update.c:(.text+0x4b0): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_inspect_reader': update.c:(.text+0x1518): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: update.c:(.text+0x1548): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to `__bad_cmpxchg' follow make[3]: *** [/builds/linux/scripts/Makefile.vmlinux:34: vmlinux] Error 1
You get a reference to __bad_cmpxchg() when someone uses cmpxchg() on a datatype that there are no CPU instructions to perform the atomic compare-and-exchange.
As we support 8-bit, 16-bit and 32-bit, I would expect that we're now seeing cmpxchg() being used on 64-bit values, which are unsupportable on 32-bit Arm.
A 64-bit cmpxchg() would fail on most 32-bit architectures, other than armv6k+ and i686+. Since this one fails on an armv6 (non-6k) build, it's probably the added 8-bit cmpxchg() that Paul talked about using for RCU, though I don't see that in linux-next here.
I htink we need to use the emulated cmpxchg8() in __cmpxchg() for this case, just like we do on other architectures that only have word size atomics.
Arnd
On Thu, May 30, 2024 at 03:27:58PM +0200, Arnd Bergmann wrote:
On Thu, May 30, 2024, at 14:26, Russell King (Oracle) wrote:
On Thu, May 30, 2024 at 05:50:52PM +0530, Naresh Kamboju wrote:
The arm builds failed on Linux next with gcc-13 and clang-18.
Config: arm imx_v6_v7_defconfig - failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
Build log:
arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_trc_cmpxchg_need_qs': update.c:(.text+0x348): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_read_unlock_trace_special': update.c:(.text+0x41c): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_read_check_handler': update.c:(.text+0x4b0): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_inspect_reader': update.c:(.text+0x1518): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: update.c:(.text+0x1548): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to `__bad_cmpxchg' follow make[3]: *** [/builds/linux/scripts/Makefile.vmlinux:34: vmlinux] Error 1
You get a reference to __bad_cmpxchg() when someone uses cmpxchg() on a datatype that there are no CPU instructions to perform the atomic compare-and-exchange.
As we support 8-bit, 16-bit and 32-bit, I would expect that we're now seeing cmpxchg() being used on 64-bit values, which are unsupportable on 32-bit Arm.
A 64-bit cmpxchg() would fail on most 32-bit architectures, other than armv6k+ and i686+. Since this one fails on an armv6 (non-6k) build, it's probably the added 8-bit cmpxchg() that Paul talked about using for RCU, though I don't see that in linux-next here.
I htink we need to use the emulated cmpxchg8() in __cmpxchg() for this case, just like we do on other architectures that only have word size atomics.
Thank you all for your testing and analysis!
I will fix this, and also pull the 8046f3005015 ("rcu-tasks: Remove open-coded one-byte cmpxchg() emulation") commit out of my -next pile in the meantime.
Thanx, Paul
On Thu, May 30, 2024 at 09:37:21AM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 03:27:58PM +0200, Arnd Bergmann wrote:
On Thu, May 30, 2024, at 14:26, Russell King (Oracle) wrote:
On Thu, May 30, 2024 at 05:50:52PM +0530, Naresh Kamboju wrote:
The arm builds failed on Linux next with gcc-13 and clang-18.
Config: arm imx_v6_v7_defconfig - failed
Reported-by: Linux Kernel Functional Testing lkft@linaro.org
Build log:
arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_trc_cmpxchg_need_qs': update.c:(.text+0x348): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `rcu_read_unlock_trace_special': update.c:(.text+0x41c): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_read_check_handler': update.c:(.text+0x4b0): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o: in function `trc_inspect_reader': update.c:(.text+0x1518): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: update.c:(.text+0x1548): undefined reference to `__bad_cmpxchg' arm-linux-gnueabihf-ld: kernel/rcu/update.o:update.c:(.text+0x1cc4): more undefined references to `__bad_cmpxchg' follow make[3]: *** [/builds/linux/scripts/Makefile.vmlinux:34: vmlinux] Error 1
You get a reference to __bad_cmpxchg() when someone uses cmpxchg() on a datatype that there are no CPU instructions to perform the atomic compare-and-exchange.
As we support 8-bit, 16-bit and 32-bit, I would expect that we're now seeing cmpxchg() being used on 64-bit values, which are unsupportable on 32-bit Arm.
A 64-bit cmpxchg() would fail on most 32-bit architectures, other than armv6k+ and i686+. Since this one fails on an armv6 (non-6k) build, it's probably the added 8-bit cmpxchg() that Paul talked about using for RCU, though I don't see that in linux-next here.
I htink we need to use the emulated cmpxchg8() in __cmpxchg() for this case, just like we do on other architectures that only have word size atomics.
Thank you all for your testing and analysis!
I will fix this, and also pull the 8046f3005015 ("rcu-tasks: Remove open-coded one-byte cmpxchg() emulation") commit out of my -next pile in the meantime.
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
Thanx, Paul
------------------------------------------------------------------------
commit 6e43483dd111cf1be58b02a45d0ca729ca2634ba Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchg
Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K.
Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7 + select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..fd9b99f4dca46 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -162,7 +162,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr);
switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ + case 1: + oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); + break; +#else case 1: do { asm volatile("@ __cmpxchg1\n"
On Thu, May 30, 2024, at 19:24, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 09:37:21AM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 03:27:58PM +0200, Arnd Bergmann wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
I think only the comment:
switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else
"min ARCH >= ARMv6K" now applies to the #else side, while the #if side is the early ARMv6 (pre-v6K).
Arnd
On Thu, May 30, 2024 at 08:05:50PM +0200, Arnd Bergmann wrote:
On Thu, May 30, 2024, at 19:24, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 09:37:21AM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 03:27:58PM +0200, Arnd Bergmann wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
I think only the comment:
switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else
"min ARCH >= ARMv6K" now applies to the #else side, while the #if side is the early ARMv6 (pre-v6K).
Good catch!
I plan to fold the following into the original with attribution.
Thanx, Paul
------------------------------------------------------------------------
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index fd9b99f4dca46..34674a4118755 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -162,11 +162,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr);
switch (size) { -#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */ case 1: oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); break; -#else +#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n"
On Thu, May 30, 2024 at 10:24:05AM -0700, Paul E. McKenney wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
An include for cmpxchg-emu.h ;)
In file included from arch/arm/include/asm/atomic.h:16, from include/linux/atomic.h:7, from include/asm-generic/bitops/lock.h:5, from arch/arm/include/asm/bitops.h:245, from include/linux/bitops.h:63, from include/linux/log2.h:12, from kernel/bounds.c:13: arch/arm/include/asm/cmpxchg.h: In function '__cmpxchg': arch/arm/include/asm/cmpxchg.h:167:26: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration] 167 | oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); | ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors
Thanx, Paul
commit 6e43483dd111cf1be58b02a45d0ca729ca2634ba Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchgUse the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K. Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
- select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..fd9b99f4dca46 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -162,7 +162,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else case 1: do { asm volatile("@ __cmpxchg1\n"
linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Thu, May 30, 2024 at 02:52:48PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 10:24:05AM -0700, Paul E. McKenney wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
An include for cmpxchg-emu.h ;)
In file included from arch/arm/include/asm/atomic.h:16, from include/linux/atomic.h:7, from include/asm-generic/bitops/lock.h:5, from arch/arm/include/asm/bitops.h:245, from include/linux/bitops.h:63, from include/linux/log2.h:12, from kernel/bounds.c:13: arch/arm/include/asm/cmpxchg.h: In function '__cmpxchg': arch/arm/include/asm/cmpxchg.h:167:26: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration] 167 | oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); | ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors
Good catch, and thank you for testing this! Does the updated version shown below do better?
Thanx, Paul
------------------------------------------------------------------------
commit 74e3470afacaa9d2f37db4773a5fef887ac4ef56 Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchg
Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K.
[ paulmck: Apply Arnd Bergmann and Nathan Chancellor feedback. ]
Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7 + select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..a428e06fe94ee 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include <linux/irqflags.h> #include <linux/prefetch.h> #include <asm/barrier.h> +#include <linux/cmpxchg-emu.h>
#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* @@ -162,7 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr);
switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */ + case 1: + oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); + break; +#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n"
On Thu, May 30, 2024 at 03:05:21PM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 02:52:48PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 10:24:05AM -0700, Paul E. McKenney wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
An include for cmpxchg-emu.h ;)
In file included from arch/arm/include/asm/atomic.h:16, from include/linux/atomic.h:7, from include/asm-generic/bitops/lock.h:5, from arch/arm/include/asm/bitops.h:245, from include/linux/bitops.h:63, from include/linux/log2.h:12, from kernel/bounds.c:13: arch/arm/include/asm/cmpxchg.h: In function '__cmpxchg': arch/arm/include/asm/cmpxchg.h:167:26: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration] 167 | oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); | ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors
Good catch, and thank you for testing this! Does the updated version shown below do better?
Yes, that matches what I tested locally before I replied initially.
Thanks for the quick fix!
Cheers, Nathan
Thanx, Paul
commit 74e3470afacaa9d2f37db4773a5fef887ac4ef56 Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchgUse the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K. [ paulmck: Apply Arnd Bergmann and Nathan Chancellor feedback. ] Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
- select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..a428e06fe94ee 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include <linux/irqflags.h> #include <linux/prefetch.h> #include <asm/barrier.h> +#include <linux/cmpxchg-emu.h> #if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* @@ -162,7 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n"
On Thu, May 30, 2024 at 04:30:53PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 03:05:21PM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 02:52:48PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 10:24:05AM -0700, Paul E. McKenney wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
An include for cmpxchg-emu.h ;)
In file included from arch/arm/include/asm/atomic.h:16, from include/linux/atomic.h:7, from include/asm-generic/bitops/lock.h:5, from arch/arm/include/asm/bitops.h:245, from include/linux/bitops.h:63, from include/linux/log2.h:12, from kernel/bounds.c:13: arch/arm/include/asm/cmpxchg.h: In function '__cmpxchg': arch/arm/include/asm/cmpxchg.h:167:26: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration] 167 | oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); | ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors
Good catch, and thank you for testing this! Does the updated version shown below do better?
Yes, that matches what I tested locally before I replied initially.
Very good! May I please add your Tested-by?
Thanx, Paul
Thanks for the quick fix!
Cheers, Nathan
Thanx, Paul
commit 74e3470afacaa9d2f37db4773a5fef887ac4ef56 Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchgUse the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K. [ paulmck: Apply Arnd Bergmann and Nathan Chancellor feedback. ] Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
- select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..a428e06fe94ee 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include <linux/irqflags.h> #include <linux/prefetch.h> #include <asm/barrier.h> +#include <linux/cmpxchg-emu.h> #if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* @@ -162,7 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n"
On Thu, May 30, 2024 at 05:35:44PM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 04:30:53PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 03:05:21PM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 02:52:48PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 10:24:05AM -0700, Paul E. McKenney wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
An include for cmpxchg-emu.h ;)
In file included from arch/arm/include/asm/atomic.h:16, from include/linux/atomic.h:7, from include/asm-generic/bitops/lock.h:5, from arch/arm/include/asm/bitops.h:245, from include/linux/bitops.h:63, from include/linux/log2.h:12, from kernel/bounds.c:13: arch/arm/include/asm/cmpxchg.h: In function '__cmpxchg': arch/arm/include/asm/cmpxchg.h:167:26: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration] 167 | oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); | ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors
Good catch, and thank you for testing this! Does the updated version shown below do better?
Yes, that matches what I tested locally before I replied initially.
Very good! May I please add your Tested-by?
Sure thing.
Tested-by: Nathan Chancellor nathan@kernel.org
commit 74e3470afacaa9d2f37db4773a5fef887ac4ef56 Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchgUse the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K. [ paulmck: Apply Arnd Bergmann and Nathan Chancellor feedback. ] Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
- select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..a428e06fe94ee 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include <linux/irqflags.h> #include <linux/prefetch.h> #include <asm/barrier.h> +#include <linux/cmpxchg-emu.h> #if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* @@ -162,7 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n"
On Fri, May 31, 2024 at 09:27:22AM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 05:35:44PM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 04:30:53PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 03:05:21PM -0700, Paul E. McKenney wrote:
On Thu, May 30, 2024 at 02:52:48PM -0700, Nathan Chancellor wrote:
On Thu, May 30, 2024 at 10:24:05AM -0700, Paul E. McKenney wrote:
And for an untested first attempt at a fix.
What did I mess up this time? ;-)
An include for cmpxchg-emu.h ;)
In file included from arch/arm/include/asm/atomic.h:16, from include/linux/atomic.h:7, from include/asm-generic/bitops/lock.h:5, from arch/arm/include/asm/bitops.h:245, from include/linux/bitops.h:63, from include/linux/log2.h:12, from kernel/bounds.c:13: arch/arm/include/asm/cmpxchg.h: In function '__cmpxchg': arch/arm/include/asm/cmpxchg.h:167:26: error: implicit declaration of function 'cmpxchg_emu_u8' [-Werror=implicit-function-declaration] 167 | oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); | ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors
Good catch, and thank you for testing this! Does the updated version shown below do better?
Yes, that matches what I tested locally before I replied initially.
Very good! May I please add your Tested-by?
Sure thing.
Tested-by: Nathan Chancellor nathan@kernel.org
Thank you! I will apply this on my next rebase.
Thanx, Paul
commit 74e3470afacaa9d2f37db4773a5fef887ac4ef56 Author: Paul E. McKenney paulmck@kernel.org Date: Thu May 30 10:11:31 2024 -0700
ARM: Emulate one-byte cmpxchgUse the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH < ARMv6K. [ paulmck: Apply Arnd Bergmann and Nathan Chancellor feedback. ] Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.... Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeL... Signed-off-by: Paul E. McKenney paulmck@kernel.org Cc: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk Cc: Arnd Bergmann arnd@arndb.de Cc: Andrew Davis afd@ti.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Eric DeVolder eric.devolder@oracle.com Cc: Rob Herring robh@kernel.org Cc: linux-arm-kernel@lists.infradead.org
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
- select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707a..a428e06fe94ee 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include <linux/irqflags.h> #include <linux/prefetch.h> #include <asm/barrier.h> +#include <linux/cmpxchg-emu.h> #if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* @@ -162,7 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* min ARCH < ARMv6K */
- case 1:
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);break;+#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n"
-
Arnd Bergmann -
Naresh Kamboju -
Nathan Chancellor -
Paul E. McKenney -
Russell King (Oracle)