Messages in this thread | | | Subject | Re: [PATCH v8 15/26] arm64: alternative: Apply alternatives early in boot process | From | Suzuki K Poulose <> | Date | Tue, 8 Jan 2019 14:51:48 +0000 |
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Hi Julien,
On 08/01/2019 14:07, Julien Thierry wrote: > From: Daniel Thompson <daniel.thompson@linaro.org> > > Currently alternatives are applied very late in the boot process (and > a long time after we enable scheduling). Some alternative sequences, > such as those that alter the way CPU context is stored, must be applied > much earlier in the boot sequence. > > Introduce apply_boot_alternatives() to allow some alternatives to be > applied immediately after we detect the CPU features of the boot CPU. > > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > [julien.thierry@arm.com: rename to fit new cpufeature framework better, > apply BOOT_SCOPE feature early in boot] > Signed-off-by: Julien Thierry <julien.thierry@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Christoffer Dall <christoffer.dall@arm.com> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > arch/arm64/include/asm/alternative.h | 1 + > arch/arm64/include/asm/cpufeature.h | 4 ++++ > arch/arm64/kernel/alternative.c | 43 +++++++++++++++++++++++++++++++----- > arch/arm64/kernel/cpufeature.c | 6 +++++ > arch/arm64/kernel/smp.c | 7 ++++++ > 5 files changed, 56 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h > index 9806a23..b9f8d78 100644 > --- a/arch/arm64/include/asm/alternative.h > +++ b/arch/arm64/include/asm/alternative.h > @@ -25,6 +25,7 @@ struct alt_instr { > typedef void (*alternative_cb_t)(struct alt_instr *alt, > __le32 *origptr, __le32 *updptr, int nr_inst); > > +void __init apply_boot_alternatives(void); > void __init apply_alternatives_all(void); > bool alternative_is_applied(u16 cpufeature); > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > index 89c3f31..e505e1f 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -391,6 +391,10 @@ static inline int cpucap_default_scope(const struct arm64_cpu_capabilities *cap) > extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS]; > extern struct static_key_false arm64_const_caps_ready; > > +/* ARM64 CAPS + alternative_cb */ > +#define ARM64_NPATCHABLE (ARM64_NCAPS + 1) > +extern DECLARE_BITMAP(boot_capabilities, ARM64_NPATCHABLE); > + > #define for_each_available_cap(cap) \ > for_each_set_bit(cap, cpu_hwcaps, ARM64_NCAPS) > > diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c > index c947d22..a9b4677 100644 > --- a/arch/arm64/kernel/alternative.c > +++ b/arch/arm64/kernel/alternative.c > @@ -155,7 +155,8 @@ static void clean_dcache_range_nopatch(u64 start, u64 end) > } while (cur += d_size, cur < end); > } > > -static void __apply_alternatives(void *alt_region, bool is_module) > +static void __apply_alternatives(void *alt_region, bool is_module, > + unsigned long *feature_mask) > { > struct alt_instr *alt; > struct alt_region *region = alt_region; > @@ -165,6 +166,9 @@ static void __apply_alternatives(void *alt_region, bool is_module) > for (alt = region->begin; alt < region->end; alt++) { > int nr_inst; > > + if (!test_bit(alt->cpufeature, feature_mask)) > + continue; > + > /* Use ARM64_CB_PATCH as an unconditional patch */ > if (alt->cpufeature < ARM64_CB_PATCH && > !cpus_have_cap(alt->cpufeature)) > @@ -203,8 +207,11 @@ static void __apply_alternatives(void *alt_region, bool is_module) > __flush_icache_all(); > isb(); > > - /* We applied all that was available */ > - bitmap_copy(applied_alternatives, cpu_hwcaps, ARM64_NCAPS); > + /* Ignore ARM64_CB bit from feature mask */ > + bitmap_or(applied_alternatives, applied_alternatives, > + feature_mask, ARM64_NCAPS); > + bitmap_and(applied_alternatives, applied_alternatives, > + cpu_hwcaps, ARM64_NCAPS); > } > } > > @@ -225,8 +232,13 @@ static int __apply_alternatives_multi_stop(void *unused) > cpu_relax(); > isb(); > } else { > + DECLARE_BITMAP(remaining_capabilities, ARM64_NPATCHABLE); > + > + bitmap_complement(remaining_capabilities, boot_capabilities, > + ARM64_NPATCHABLE); > + > BUG_ON(all_alternatives_applied); > - __apply_alternatives(®ion, false); > + __apply_alternatives(®ion, false, remaining_capabilities); > /* Barriers provided by the cache flushing */ > WRITE_ONCE(all_alternatives_applied, 1); > } > @@ -240,6 +252,24 @@ void __init apply_alternatives_all(void) > stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask); > } > > +/* > + * This is called very early in the boot process (directly after we run > + * a feature detect on the boot CPU). No need to worry about other CPUs > + * here. > + */ > +void __init apply_boot_alternatives(void) > +{ > + struct alt_region region = { > + .begin = (struct alt_instr *)__alt_instructions, > + .end = (struct alt_instr *)__alt_instructions_end, > + }; > + > + /* If called on non-boot cpu things could go wrong */ > + WARN_ON(smp_processor_id() != 0); > + > + __apply_alternatives(®ion, false, &boot_capabilities[0]); > +} > + > #ifdef CONFIG_MODULES > void apply_alternatives_module(void *start, size_t length) > { > @@ -247,7 +277,10 @@ void apply_alternatives_module(void *start, size_t length) > .begin = start, > .end = start + length, > }; > + DECLARE_BITMAP(all_capabilities, ARM64_NPATCHABLE); > + > + bitmap_fill(all_capabilities, ARM64_NPATCHABLE); > > - __apply_alternatives(®ion, true); > + __apply_alternatives(®ion, true, &all_capabilities[0]); > } > #endif > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 84fa5be..71c8d4f 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -54,6 +54,9 @@ > EXPORT_SYMBOL(cpu_hwcaps); > static struct arm64_cpu_capabilities const __ro_after_init *cpu_hwcaps_ptrs[ARM64_NCAPS]; > > +/* Need also bit for ARM64_CB_PATCH */ > +DECLARE_BITMAP(boot_capabilities, ARM64_NPATCHABLE); > + > /* > * Flag to indicate if we have computed the system wide > * capabilities based on the boot time active CPUs. This > @@ -1672,6 +1675,9 @@ static void update_cpu_capabilities(u16 scope_mask) > if (caps->desc) > pr_info("detected: %s\n", caps->desc); > cpus_set_cap(caps->capability); > + > + if (caps->type & SCOPE_BOOT_CPU)
You may want to do : if (scope_mask & SCOPE_BOOT_CPU)
for a tighter check to ensure this doesn't update the boot_capabilities after we have applied the boot_scope alternatives and miss applying the alternatives for those, should someone add a multi-scope (i.e SCOPE_BOOT_CPU and something else) capability (even by mistake).
With that:
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
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