| Message ID | 52137CD5.7010201@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Aug 20, 2013 at 03:27:33PM +0100, Sudeep KarkadaNagesha wrote: > On 20/08/13 14:27, Will Deacon wrote: > > On Tue, Aug 13, 2013 at 06:29:42PM +0100, Sudeep KarkadaNagesha wrote: > >> diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h > >> index 6d4482f..effd8f9 100644 > >> --- a/arch/arm64/include/asm/hwcap.h > >> +++ b/arch/arm64/include/asm/hwcap.h > >> @@ -30,6 +30,7 @@ > >> #define COMPAT_HWCAP_IDIVA (1 << 17) > >> #define COMPAT_HWCAP_IDIVT (1 << 18) > >> #define COMPAT_HWCAP_IDIV (COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT) > >> +#define COMPAT_HWCAP_EVTSTRM (1 << 21) > > > > Looking at the context, we should also add COMPAT_HWCAP_LPAE as a separate > > patch (not part of this series). > > > Ok make sense, I can do that. IIUC even this needs at least under some > config option, assuming can't be dynamic ? I'm not sure I follow you... if you're asking whether the LPAE HWCAP should be dynamic for ARMv8, then no, since the capabilities offered by LPAE are included in ARMv8 as far as userspace is concerned. > >> #ifndef __ASSEMBLY__ > >> /* > >> @@ -41,7 +42,8 @@ > >> COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\ > >> COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\ > >> COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\ > >> - COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV) > >> + COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\ > >> + COMPAT_HWCAP_EVTSTRM) > > > > So here you're hardcoding COMPAT_HWCAP_EVTSTRM in the COMPAT_ELF_HWCAP, yet > > we only enable the native one from the arch-timer driver. The question then is > > "Can we rely on the event-stream working for AArch64?". If so, we don't need > > the native hwcap at all. If not, then we need to make the compat hwcap > > dynamic. > > How about something like this ? I am not sure if > arch/arm64/kernel/setup.c is apt place for compat_elf_hwcap though. Looks like the right sort of idea, yes. I can't think of a better place to put it. You could adjust it slightly so that COMPAT_ELF_HWCAP stays like it is, with an extra '| compat_dyn_elf_hwcap' on the end, but I have no real preference. Will
On 20/08/13 17:16, Will Deacon wrote: > On Tue, Aug 20, 2013 at 03:27:33PM +0100, Sudeep KarkadaNagesha wrote: >> On 20/08/13 14:27, Will Deacon wrote: >>> On Tue, Aug 13, 2013 at 06:29:42PM +0100, Sudeep KarkadaNagesha wrote: >>>> diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h >>>> index 6d4482f..effd8f9 100644 >>>> --- a/arch/arm64/include/asm/hwcap.h >>>> +++ b/arch/arm64/include/asm/hwcap.h >>>> @@ -30,6 +30,7 @@ >>>> #define COMPAT_HWCAP_IDIVA (1 << 17) >>>> #define COMPAT_HWCAP_IDIVT (1 << 18) >>>> #define COMPAT_HWCAP_IDIV (COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT) >>>> +#define COMPAT_HWCAP_EVTSTRM (1 << 21) >>> >>> Looking at the context, we should also add COMPAT_HWCAP_LPAE as a separate >>> patch (not part of this series). >>> >> Ok make sense, I can do that. IIUC even this needs at least under some >> config option, assuming can't be dynamic ? > > I'm not sure I follow you... if you're asking whether the LPAE HWCAP should > be dynamic for ARMv8, then no, since the capabilities offered by LPAE are > included in ARMv8 as far as userspace is concerned. > Ok, then it can be in the default list of compat hwcap. >>>> #ifndef __ASSEMBLY__ >>>> /* >>>> @@ -41,7 +42,8 @@ >>>> COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\ >>>> COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\ >>>> COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\ >>>> - COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV) >>>> + COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\ >>>> + COMPAT_HWCAP_EVTSTRM) >>> >>> So here you're hardcoding COMPAT_HWCAP_EVTSTRM in the COMPAT_ELF_HWCAP, yet >>> we only enable the native one from the arch-timer driver. The question then is >>> "Can we rely on the event-stream working for AArch64?". If so, we don't need >>> the native hwcap at all. If not, then we need to make the compat hwcap >>> dynamic. >> >> How about something like this ? I am not sure if >> arch/arm64/kernel/setup.c is apt place for compat_elf_hwcap though. > > Looks like the right sort of idea, yes. I can't think of a better place to > put it. You could adjust it slightly so that COMPAT_ELF_HWCAP stays like it > is, with an extra '| compat_dyn_elf_hwcap' on the end, but I have no real > preference. > Yes that's better, will do this way. Regards, Sudeep
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index 43f322a..a7d33a8 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -120,6 +120,9 @@ static inline void arch_counter_set_user_access(int divider) static inline void arch_timer_set_hwcap_evtstrm(void) { elf_hwcap |= HWCAP_EVTSTRM; +#ifdef CONFIG_COMPAT + compat_elf_hwcap |= COMPAT_HWCAP_EVTSTRM; +#endif } static inline u64 arch_counter_get_cntvct(void) diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h index effd8f9..9633db0 100644 --- a/arch/arm64/include/asm/hwcap.h +++ b/arch/arm64/include/asm/hwcap.h @@ -32,19 +32,24 @@ #define COMPAT_HWCAP_IDIV (COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT) #define COMPAT_HWCAP_EVTSTRM (1 << 21) +#define COMPAT_ELF_HWCAP_DEFAULT \ + (COMPAT_HWCAP_HALF|COMPAT_HWCAP_THUMB|\ + COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\ + COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\ + COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\ + COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV) #ifndef __ASSEMBLY__ /* * This yields a mask that user programs can use to figure out what * instruction set this cpu supports. */ #define ELF_HWCAP (elf_hwcap) -#define COMPAT_ELF_HWCAP (COMPAT_HWCAP_HALF|COMPAT_HWCAP_THUMB|\ - COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\ - COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\ - COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\ - COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\ - COMPAT_HWCAP_EVTSTRM) - extern unsigned int elf_hwcap; + +#ifdef CONFIG_COMPAT +#define COMPAT_ELF_HWCAP (compat_elf_hwcap) +extern unsigned int compat_elf_hwcap; +#endif + #endif #endif diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 1111833..990fc98 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -60,6 +60,11 @@ EXPORT_SYMBOL(processor_id); unsigned int elf_hwcap __read_mostly; EXPORT_SYMBOL_GPL(elf_hwcap); +#ifdef CONFIG_COMPAT +unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT; +EXPORT_SYMBOL_GPL(compat_elf_hwcap); +#endif + static const char *cpu_name; static const char *machine_name; phys_addr_t __fdt_pointer __initdata;