| Message ID | 1583476525-13505-2-git-send-email-amit.kachhap@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: return address signing | expand |
Hi Amit, On 3/6/20 6:35 AM, Amit Daniel Kachhap wrote: > Some existing/future meta cpucaps match need the presence of individual > cpucaps. Currently the individual cpucaps checks it via an array based > flag and this introduces dependency on the array entry order. > This limitation exists only for system scope cpufeature. > > This patch introduces an internal helper function (__system_matches_cap) > to invoke the matching handler for system scope. This helper has to be > used during a narrow window when, > - The system wide safe registers are set with all the SMP CPUs and, > - The SYSTEM_FEATURE cpu_hwcaps may not have been set. > > Normal users should use the existing cpus_have_{const_}cap() global > function. > > Suggested-by: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> > --- > arch/arm64/kernel/cpufeature.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 0b67156..3818685 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -116,6 +116,8 @@ cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused) > > static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap); > > +static bool __system_matches_cap(unsigned int n); > + > /* > * NOTE: Any changes to the visibility of features should be kept in > * sync with the documentation of the CPU feature register ABI. > @@ -2146,6 +2148,17 @@ bool this_cpu_has_cap(unsigned int n) > return false; > } > Nit: you might want to add a comment on top of __system_matches_cap() that explains why we introduce this function and when should be used. Otherwise looks good to me. Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> > +static bool __system_matches_cap(unsigned int n) > +{ > + if (n < ARM64_NCAPS) { > + const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[n]; > + > + if (cap) > + return cap->matches(cap, SCOPE_SYSTEM); > + } > + return false; > +} > + > void cpu_set_feature(unsigned int num) > { > WARN_ON(num >= MAX_CPU_FEATURES); > @@ -2218,7 +2231,7 @@ void __init setup_cpu_features(void) > static bool __maybe_unused > cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused) > { > - return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO)); > + return (__system_matches_cap(ARM64_HAS_PAN) && !__system_matches_cap(ARM64_HAS_UAO)); > } > > static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap) >
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 0b67156..3818685 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -116,6 +116,8 @@ cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused) static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap); +static bool __system_matches_cap(unsigned int n); + /* * NOTE: Any changes to the visibility of features should be kept in * sync with the documentation of the CPU feature register ABI. @@ -2146,6 +2148,17 @@ bool this_cpu_has_cap(unsigned int n) return false; } +static bool __system_matches_cap(unsigned int n) +{ + if (n < ARM64_NCAPS) { + const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[n]; + + if (cap) + return cap->matches(cap, SCOPE_SYSTEM); + } + return false; +} + void cpu_set_feature(unsigned int num) { WARN_ON(num >= MAX_CPU_FEATURES); @@ -2218,7 +2231,7 @@ void __init setup_cpu_features(void) static bool __maybe_unused cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused) { - return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO)); + return (__system_matches_cap(ARM64_HAS_PAN) && !__system_matches_cap(ARM64_HAS_UAO)); } static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap)
Some existing/future meta cpucaps match need the presence of individual cpucaps. Currently the individual cpucaps checks it via an array based flag and this introduces dependency on the array entry order. This limitation exists only for system scope cpufeature. This patch introduces an internal helper function (__system_matches_cap) to invoke the matching handler for system scope. This helper has to be used during a narrow window when, - The system wide safe registers are set with all the SMP CPUs and, - The SYSTEM_FEATURE cpu_hwcaps may not have been set. Normal users should use the existing cpus_have_{const_}cap() global function. Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> --- arch/arm64/kernel/cpufeature.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)