Re: [PATCH v14 3/9] fw_cfg: fix sparse warnings in fw_cfg_sel_endianness()
On Thu, Feb 15, 2018 at 10:34:28AM +0100, Marc-Andre Lureau wrote: > On Wed, Feb 14, 2018 at 9:46 PM, Michael S. Tsirkin wrote: > > On Wed, Feb 14, 2018 at 03:18:44PM +0100, Marc-André Lureau wrote: > >> The function is used for both LE & BE target type, use __force casting. > >> > >> Fixes: > >> $ make C=1 CF=-D__CHECK_ENDIAN__ drivers/firmware/qemu_fw_cfg.o > >> > >> drivers/firmware/qemu_fw_cfg.c:55:33: warning: restricted __be16 degrades > >> to integer > >> drivers/firmware/qemu_fw_cfg.c:55:52: warning: restricted __le16 degrades > >> to integer > >> > >> Signed-off-by: Marc-André Lureau > >> --- > >> drivers/firmware/qemu_fw_cfg.c | 4 +++- > >> 1 file changed, 3 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/firmware/qemu_fw_cfg.c > >> b/drivers/firmware/qemu_fw_cfg.c > >> index 90f467232777..85e693287d87 100644 > >> --- a/drivers/firmware/qemu_fw_cfg.c > >> +++ b/drivers/firmware/qemu_fw_cfg.c > >> @@ -52,7 +52,9 @@ static DEFINE_MUTEX(fw_cfg_dev_lock); > >> /* pick appropriate endianness for selector key */ > >> static inline u16 fw_cfg_sel_endianness(u16 key) > >> { > >> - return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); > >> + return fw_cfg_is_mmio ? > >> + (u16 __force)cpu_to_be16(key) : > >> + (u16 __force)cpu_to_le16(key); > >> } > >> > >> /* read chunk of given fw_cfg blob (caller responsible for sanity-check) > >> */ > > > > Well the caller does cpu_to_le16 on the result ... > > All this makes my head spin. > > > > IMHO what you want is a wrapper that does iowrite and iowritebe > > rather than __force. > > iowrite16(key) is the same as iowrite16(cpu_to_le16(key)) ? There is > no iowrite16le()... Yes. > Is this equivalent, and not introducing regressions? > > static inline u16 fw_cfg_sel_endianness(u16 key) > +static void fw_cfg_sel_endianness(u16 key) > { > - return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); For mmio on LE it does 1 swap. On BE 1 swap. For non mmio on LE it does no swaps. On BE 1 swap. Fair summary? And is this actually the intended behaviour. > + if (fw_cfg_is_mmio) > + iowrite16be(key, fw_cfg_reg_ctrl); > + else > + iowrite16(key, fw_cfg_reg_ctrl); this behaves differently. donnu if that's a bug or a feature. You will have to find out. > } > > /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ > @@ -74,7 +77,7 @@ static inline void fw_cfg_read_blob(u16 key, > } > > mutex_lock(&fw_cfg_dev_lock); > - iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl); > + fw_cfg_sel_endianness(key); > > > > > > >> -- > >> 2.16.1.73.g5832b7e9f2
Re: [PATCH v14 3/9] fw_cfg: fix sparse warnings in fw_cfg_sel_endianness()
On Wed, Feb 14, 2018 at 9:46 PM, Michael S. Tsirkin wrote: > On Wed, Feb 14, 2018 at 03:18:44PM +0100, Marc-André Lureau wrote: >> The function is used for both LE & BE target type, use __force casting. >> >> Fixes: >> $ make C=1 CF=-D__CHECK_ENDIAN__ drivers/firmware/qemu_fw_cfg.o >> >> drivers/firmware/qemu_fw_cfg.c:55:33: warning: restricted __be16 degrades to >> integer >> drivers/firmware/qemu_fw_cfg.c:55:52: warning: restricted __le16 degrades to >> integer >> >> Signed-off-by: Marc-André Lureau >> --- >> drivers/firmware/qemu_fw_cfg.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c >> index 90f467232777..85e693287d87 100644 >> --- a/drivers/firmware/qemu_fw_cfg.c >> +++ b/drivers/firmware/qemu_fw_cfg.c >> @@ -52,7 +52,9 @@ static DEFINE_MUTEX(fw_cfg_dev_lock); >> /* pick appropriate endianness for selector key */ >> static inline u16 fw_cfg_sel_endianness(u16 key) >> { >> - return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); >> + return fw_cfg_is_mmio ? >> + (u16 __force)cpu_to_be16(key) : >> + (u16 __force)cpu_to_le16(key); >> } >> >> /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ > > Well the caller does cpu_to_le16 on the result ... > All this makes my head spin. > > IMHO what you want is a wrapper that does iowrite and iowritebe > rather than __force. iowrite16(key) is the same as iowrite16(cpu_to_le16(key)) ? There is no iowrite16le()... Is this equivalent, and not introducing regressions? static inline u16 fw_cfg_sel_endianness(u16 key) +static void fw_cfg_sel_endianness(u16 key) { - return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); + if (fw_cfg_is_mmio) + iowrite16be(key, fw_cfg_reg_ctrl); + else + iowrite16(key, fw_cfg_reg_ctrl); } /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ @@ -74,7 +77,7 @@ static inline void fw_cfg_read_blob(u16 key, } mutex_lock(&fw_cfg_dev_lock); - iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl); + fw_cfg_sel_endianness(key); > > >> -- >> 2.16.1.73.g5832b7e9f2
Re: [PATCH v14 3/9] fw_cfg: fix sparse warnings in fw_cfg_sel_endianness()
On Wed, Feb 14, 2018 at 03:18:44PM +0100, Marc-André Lureau wrote: > The function is used for both LE & BE target type, use __force casting. > > Fixes: > $ make C=1 CF=-D__CHECK_ENDIAN__ drivers/firmware/qemu_fw_cfg.o > > drivers/firmware/qemu_fw_cfg.c:55:33: warning: restricted __be16 degrades to > integer > drivers/firmware/qemu_fw_cfg.c:55:52: warning: restricted __le16 degrades to > integer > > Signed-off-by: Marc-André Lureau > --- > drivers/firmware/qemu_fw_cfg.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c > index 90f467232777..85e693287d87 100644 > --- a/drivers/firmware/qemu_fw_cfg.c > +++ b/drivers/firmware/qemu_fw_cfg.c > @@ -52,7 +52,9 @@ static DEFINE_MUTEX(fw_cfg_dev_lock); > /* pick appropriate endianness for selector key */ > static inline u16 fw_cfg_sel_endianness(u16 key) > { > - return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); > + return fw_cfg_is_mmio ? > + (u16 __force)cpu_to_be16(key) : > + (u16 __force)cpu_to_le16(key); > } > > /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ Well the caller does cpu_to_le16 on the result ... All this makes my head spin. IMHO what you want is a wrapper that does iowrite and iowritebe rather than __force. > -- > 2.16.1.73.g5832b7e9f2
[PATCH v14 3/9] fw_cfg: fix sparse warnings in fw_cfg_sel_endianness()
The function is used for both LE & BE target type, use __force casting. Fixes: $ make C=1 CF=-D__CHECK_ENDIAN__ drivers/firmware/qemu_fw_cfg.o drivers/firmware/qemu_fw_cfg.c:55:33: warning: restricted __be16 degrades to integer drivers/firmware/qemu_fw_cfg.c:55:52: warning: restricted __le16 degrades to integer Signed-off-by: Marc-André Lureau --- drivers/firmware/qemu_fw_cfg.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c index 90f467232777..85e693287d87 100644 --- a/drivers/firmware/qemu_fw_cfg.c +++ b/drivers/firmware/qemu_fw_cfg.c @@ -52,7 +52,9 @@ static DEFINE_MUTEX(fw_cfg_dev_lock); /* pick appropriate endianness for selector key */ static inline u16 fw_cfg_sel_endianness(u16 key) { - return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key); + return fw_cfg_is_mmio ? + (u16 __force)cpu_to_be16(key) : + (u16 __force)cpu_to_le16(key); } /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */ -- 2.16.1.73.g5832b7e9f2