| Message ID | 20160816142201.12672-1-sw0312.kim@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Aug 16, 2016 at 11:22:01PM +0900, Seung-Woo Kim wrote: > From pwm_samsung_calc_tin(), there is routine to find the lowest > divider possible to generate lower frequency than requested one. > But it is always possible to generate requested frequency with > large enough modulation bits except s3c24xx, so this patch fixes > to use lowest div for the case. This patch removes following UBSAN > warning: > > UBSAN: Undefined behaviour in drivers/pwm/pwm-samsung.c:197:13 > shift exponent 32 is too large for 32-bit type 'long unsigned int' > [...] > [<c0670248>] (ubsan_epilogue) from [<c06707b4>] (__ubsan_handle_shift_out_of_bounds+0xd8/0x120) > [<c06707b4>] (__ubsan_handle_shift_out_of_bounds) from [<c0694b28>] (pwm_samsung_config+0x508/0x6a4) > [<c0694b28>] (pwm_samsung_config) from [<c069286c>] (pwm_apply_state+0x174/0x40c) > [<c069286c>] (pwm_apply_state) from [<c0b2e070>] (pwm_fan_probe+0xc8/0x488) > [<c0b2e070>] (pwm_fan_probe) from [<c07ba8b0>] (platform_drv_probe+0x70/0x150) > [...] > > Cc: Tomasz Figa <tomasz.figa@gmail.com> > Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com> > --- > Changes from v1 > * Remove too complex condition, instead, just checking simple variant->bits as Krzysztof's suggestion > * Add comment from Tomasz > > The UBSAN warning from ARM is reported with the patch in following link: > https://patchwork.kernel.org/patch/9189575/ > --- > drivers/pwm/pwm-samsung.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Best regards, Krzysztof
On Tue, Aug 16, 2016 at 11:22:01PM +0900, Seung-Woo Kim wrote: > From pwm_samsung_calc_tin(), there is routine to find the lowest > divider possible to generate lower frequency than requested one. > But it is always possible to generate requested frequency with > large enough modulation bits except s3c24xx, so this patch fixes > to use lowest div for the case. This patch removes following UBSAN > warning: > > UBSAN: Undefined behaviour in drivers/pwm/pwm-samsung.c:197:13 > shift exponent 32 is too large for 32-bit type 'long unsigned int' > [...] > [<c0670248>] (ubsan_epilogue) from [<c06707b4>] (__ubsan_handle_shift_out_of_bounds+0xd8/0x120) > [<c06707b4>] (__ubsan_handle_shift_out_of_bounds) from [<c0694b28>] (pwm_samsung_config+0x508/0x6a4) > [<c0694b28>] (pwm_samsung_config) from [<c069286c>] (pwm_apply_state+0x174/0x40c) > [<c069286c>] (pwm_apply_state) from [<c0b2e070>] (pwm_fan_probe+0xc8/0x488) > [<c0b2e070>] (pwm_fan_probe) from [<c07ba8b0>] (platform_drv_probe+0x70/0x150) > [...] > > Cc: Tomasz Figa <tomasz.figa@gmail.com> > Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com> > --- > Changes from v1 > * Remove too complex condition, instead, just checking simple variant->bits as Krzysztof's suggestion > * Add comment from Tomasz > > The UBSAN warning from ARM is reported with the patch in following link: > https://patchwork.kernel.org/patch/9189575/ > --- > drivers/pwm/pwm-samsung.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) Applied, thanks. Thierry
diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c index ada2d32..f113cda 100644 --- a/drivers/pwm/pwm-samsung.c +++ b/drivers/pwm/pwm-samsung.c @@ -193,9 +193,18 @@ static unsigned long pwm_samsung_calc_tin(struct samsung_pwm_chip *chip, * divider settings and choose the lowest divisor that can generate * frequencies lower than requested. */ - for (div = variant->div_base; div < 4; ++div) - if ((rate >> (variant->bits + div)) < freq) - break; + if (variant->bits < 32) { + /* Only for s3c24xx */ + for (div = variant->div_base; div < 4; ++div) + if ((rate >> (variant->bits + div)) < freq) + break; + } else { + /* + * Other variants have enough counter bits to generate any + * requested rate, so no need to check higher divisors. + */ + div = variant->div_base; + } pwm_samsung_set_divisor(chip, chan, BIT(div));
From pwm_samsung_calc_tin(), there is routine to find the lowest divider possible to generate lower frequency than requested one. But it is always possible to generate requested frequency with large enough modulation bits except s3c24xx, so this patch fixes to use lowest div for the case. This patch removes following UBSAN warning: UBSAN: Undefined behaviour in drivers/pwm/pwm-samsung.c:197:13 shift exponent 32 is too large for 32-bit type 'long unsigned int' [...] [<c0670248>] (ubsan_epilogue) from [<c06707b4>] (__ubsan_handle_shift_out_of_bounds+0xd8/0x120) [<c06707b4>] (__ubsan_handle_shift_out_of_bounds) from [<c0694b28>] (pwm_samsung_config+0x508/0x6a4) [<c0694b28>] (pwm_samsung_config) from [<c069286c>] (pwm_apply_state+0x174/0x40c) [<c069286c>] (pwm_apply_state) from [<c0b2e070>] (pwm_fan_probe+0xc8/0x488) [<c0b2e070>] (pwm_fan_probe) from [<c07ba8b0>] (platform_drv_probe+0x70/0x150) [...] Cc: Tomasz Figa <tomasz.figa@gmail.com> Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com> --- Changes from v1 * Remove too complex condition, instead, just checking simple variant->bits as Krzysztof's suggestion * Add comment from Tomasz The UBSAN warning from ARM is reported with the patch in following link: https://patchwork.kernel.org/patch/9189575/ --- drivers/pwm/pwm-samsung.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)