| Message ID | 20230815-watchdog-xilinx-div_u64-v1-1-20b0b5a65c2e@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | watchdog: xilinx_wwdt: Use div_u64() in xilinx_wwdt_start() | expand |
On Tue, Aug 15, 2023 at 12:06:50PM -0700, Nathan Chancellor wrote: > After commit f1a43aadb5a6 ("watchdog: Enable COMPILE_TEST for more > drivers"), it is possible to enable this driver on 32-bit architectures. > When building for those architectures with clang, there is an error due > to a 64-bit division in xilinx_wwdt_start(): > > ERROR: modpost: "__aeabi_uldivmod" [drivers/watchdog/xilinx_wwdt.ko] undefined! > > Use div_u64() to fix this, which takes a 64-bit dividend and 32-bit > divisor. GCC likely avoids the same error due to optimizations it > employs to transform division by a constant into other equivalent > operations, which may be different than what is implemented in clang. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1915 > Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > drivers/watchdog/xilinx_wwdt.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/watchdog/xilinx_wwdt.c b/drivers/watchdog/xilinx_wwdt.c > index 1d998db41533..d271e2e8d6e2 100644 > --- a/drivers/watchdog/xilinx_wwdt.c > +++ b/drivers/watchdog/xilinx_wwdt.c > @@ -9,6 +9,7 @@ > #include <linux/interrupt.h> > #include <linux/io.h> > #include <linux/ioport.h> > +#include <linux/math64.h> > #include <linux/mod_devicetable.h> > #include <linux/module.h> > #include <linux/platform_device.h> > @@ -71,7 +72,7 @@ static int xilinx_wwdt_start(struct watchdog_device *wdd) > > /* Calculate timeout count */ > time_out = xdev->freq * wdd->timeout; > - closed_timeout = (time_out * xdev->close_percent) / 100; > + closed_timeout = div_u64(time_out * xdev->close_percent, 100); > open_timeout = time_out - closed_timeout; > wdd->min_hw_heartbeat_ms = xdev->close_percent * 10 * wdd->timeout; > > > --- > base-commit: 8a504bd61ec7b3ddd72680e15775f2c7c0f9e894 > change-id: 20230815-watchdog-xilinx-div_u64-85c27c650493 > > Best regards, > -- > Nathan Chancellor <nathan@kernel.org> >
On Tue, Aug 15, 2023 at 12:06:50PM -0700, Nathan Chancellor wrote: > After commit f1a43aadb5a6 ("watchdog: Enable COMPILE_TEST for more > drivers"), it is possible to enable this driver on 32-bit architectures. > When building for those architectures with clang, there is an error due > to a 64-bit division in xilinx_wwdt_start(): > > ERROR: modpost: "__aeabi_uldivmod" [drivers/watchdog/xilinx_wwdt.ko] undefined! > > Use div_u64() to fix this, which takes a 64-bit dividend and 32-bit > divisor. GCC likely avoids the same error due to optimizations it > employs to transform division by a constant into other equivalent > operations, which may be different than what is implemented in clang. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1915 > Signed-off-by: Nathan Chancellor <nathan@kernel.org> > --- > drivers/watchdog/xilinx_wwdt.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) Thanks for the fix. Also reported by 0-day with a similar failure: All errors (new ones prefixed by >>): microblaze-linux-ld: drivers/watchdog/xilinx_wwdt.o: in function `xilinx_wwdt_start': >> drivers/watchdog/xilinx_wwdt.c:74: undefined reference to `__udivdi3' Acked-by: Rob Herring <robh@kernel.org>
diff --git a/drivers/watchdog/xilinx_wwdt.c b/drivers/watchdog/xilinx_wwdt.c index 1d998db41533..d271e2e8d6e2 100644 --- a/drivers/watchdog/xilinx_wwdt.c +++ b/drivers/watchdog/xilinx_wwdt.c @@ -9,6 +9,7 @@ #include <linux/interrupt.h> #include <linux/io.h> #include <linux/ioport.h> +#include <linux/math64.h> #include <linux/mod_devicetable.h> #include <linux/module.h> #include <linux/platform_device.h> @@ -71,7 +72,7 @@ static int xilinx_wwdt_start(struct watchdog_device *wdd) /* Calculate timeout count */ time_out = xdev->freq * wdd->timeout; - closed_timeout = (time_out * xdev->close_percent) / 100; + closed_timeout = div_u64(time_out * xdev->close_percent, 100); open_timeout = time_out - closed_timeout; wdd->min_hw_heartbeat_ms = xdev->close_percent * 10 * wdd->timeout;
After commit f1a43aadb5a6 ("watchdog: Enable COMPILE_TEST for more drivers"), it is possible to enable this driver on 32-bit architectures. When building for those architectures with clang, there is an error due to a 64-bit division in xilinx_wwdt_start(): ERROR: modpost: "__aeabi_uldivmod" [drivers/watchdog/xilinx_wwdt.ko] undefined! Use div_u64() to fix this, which takes a 64-bit dividend and 32-bit divisor. GCC likely avoids the same error due to optimizations it employs to transform division by a constant into other equivalent operations, which may be different than what is implemented in clang. Link: https://github.com/ClangBuiltLinux/linux/issues/1915 Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- drivers/watchdog/xilinx_wwdt.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- base-commit: 8a504bd61ec7b3ddd72680e15775f2c7c0f9e894 change-id: 20230815-watchdog-xilinx-div_u64-85c27c650493 Best regards,