| Message ID | 20210113014047.14371-2-justin.he@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Avoid booting stall caused by | expand |
On Wed, Jan 13, 2021 at 09:40:46AM +0800, Jia He wrote: > Move init_cpu_features() ahead of setup_arch()->early_fixmap_init(), which > is the preparation work for checking the condition to assign > arm64_use_ng_mappings as cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0). > > Besides, jump_label_init() is also moved ahead because > cpus_have_const_cap() depends on static key enable api. > > Percpu helpers should be avoided in cpuinfo_store_boot_cpu() before percpu > init at main.c::setup_per_cpu_areas() > > Signed-off-by: Jia He <justin.he@arm.com> > --- > arch/arm64/include/asm/cpu.h | 1 + > arch/arm64/kernel/cpuinfo.c | 13 ++++++++++--- > arch/arm64/kernel/setup.c | 14 +++++++++----- > arch/arm64/kernel/smp.c | 3 +-- > 4 files changed, 21 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h > index 7faae6ff3ab4..59f36f5e3c04 100644 > --- a/arch/arm64/include/asm/cpu.h > +++ b/arch/arm64/include/asm/cpu.h > @@ -63,6 +63,7 @@ DECLARE_PER_CPU(struct cpuinfo_arm64, cpu_data); > > void cpuinfo_store_cpu(void); > void __init cpuinfo_store_boot_cpu(void); > +void __init save_boot_cpuinfo_data(void); > > void __init init_cpu_features(struct cpuinfo_arm64 *info); > void update_cpu_features(int cpu, struct cpuinfo_arm64 *info, > diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c > index 77605aec25fe..f8de5b8bae20 100644 > --- a/arch/arm64/kernel/cpuinfo.c > +++ b/arch/arm64/kernel/cpuinfo.c > @@ -413,9 +413,16 @@ void cpuinfo_store_cpu(void) > > void __init cpuinfo_store_boot_cpu(void) > { > - struct cpuinfo_arm64 *info = &per_cpu(cpu_data, 0); > - __cpuinfo_store_cpu(info); > + __cpuinfo_store_cpu(&boot_cpu_data); > > - boot_cpu_data = *info; > init_cpu_features(&boot_cpu_data); > } > + > +void __init save_boot_cpuinfo_data(void) > +{ > + struct cpuinfo_arm64 *info; > + > + set_my_cpu_offset(per_cpu_offset(smp_processor_id())); > + info = &per_cpu(cpu_data, 0); > + *info = boot_cpu_data; > +} > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index 1a57a76e1cc2..e078ab068f3b 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -297,16 +297,20 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) > */ > arm64_use_ng_mappings = kaslr_requires_kpti(); > > - early_fixmap_init(); > - early_ioremap_init(); > - > - setup_machine_fdt(__fdt_pointer); > - > /* > * Initialise the static keys early as they may be enabled by the > * cpufeature code and early parameters. > */ > jump_label_init(); I don't think your patch changes this, but afaict jump_label_init() uses per-cpu variables via cpus_read_lock(), yet we don't initialise our offset until later on. Any idea how that works? Will
On Tue, Jan 26, 2021 at 01:57:13PM +0000, Will Deacon wrote: > > @@ -297,16 +297,20 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) > > */ > > arm64_use_ng_mappings = kaslr_requires_kpti(); > > > > - early_fixmap_init(); > > - early_ioremap_init(); > > - > > - setup_machine_fdt(__fdt_pointer); > > - > > /* > > * Initialise the static keys early as they may be enabled by the > > * cpufeature code and early parameters. > > */ > > jump_label_init(); > > I don't think your patch changes this, but afaict jump_label_init() uses > per-cpu variables via cpus_read_lock(), yet we don't initialise our offset > until later on. Any idea how that works? We initialize the boot CPU's offset twice during boot, once before this in smp_setup_processor_id(), and once afterwards in smp_prepare_boot_cpu() since setup_per_cpu_areas() will allocate a new region for CPU0. IIUC per-cpu writes before smp_prepare_boot_cpu() are potentially dodgy since they might be copied to other CPUs, but reads are all fine. Mark.
diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h index 7faae6ff3ab4..59f36f5e3c04 100644 --- a/arch/arm64/include/asm/cpu.h +++ b/arch/arm64/include/asm/cpu.h @@ -63,6 +63,7 @@ DECLARE_PER_CPU(struct cpuinfo_arm64, cpu_data); void cpuinfo_store_cpu(void); void __init cpuinfo_store_boot_cpu(void); +void __init save_boot_cpuinfo_data(void); void __init init_cpu_features(struct cpuinfo_arm64 *info); void update_cpu_features(int cpu, struct cpuinfo_arm64 *info, diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index 77605aec25fe..f8de5b8bae20 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -413,9 +413,16 @@ void cpuinfo_store_cpu(void) void __init cpuinfo_store_boot_cpu(void) { - struct cpuinfo_arm64 *info = &per_cpu(cpu_data, 0); - __cpuinfo_store_cpu(info); + __cpuinfo_store_cpu(&boot_cpu_data); - boot_cpu_data = *info; init_cpu_features(&boot_cpu_data); } + +void __init save_boot_cpuinfo_data(void) +{ + struct cpuinfo_arm64 *info; + + set_my_cpu_offset(per_cpu_offset(smp_processor_id())); + info = &per_cpu(cpu_data, 0); + *info = boot_cpu_data; +} diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 1a57a76e1cc2..e078ab068f3b 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -297,16 +297,20 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) */ arm64_use_ng_mappings = kaslr_requires_kpti(); - early_fixmap_init(); - early_ioremap_init(); - - setup_machine_fdt(__fdt_pointer); - /* * Initialise the static keys early as they may be enabled by the * cpufeature code and early parameters. */ jump_label_init(); + + /* Init the cpu feature codes for boot cpu */ + cpuinfo_store_boot_cpu(); + + early_fixmap_init(); + early_ioremap_init(); + + setup_machine_fdt(__fdt_pointer); + parse_early_param(); /* diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 2499b895efea..3df1f5b1da0b 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -449,8 +449,7 @@ void __init smp_cpus_done(unsigned int max_cpus) void __init smp_prepare_boot_cpu(void) { - set_my_cpu_offset(per_cpu_offset(smp_processor_id())); - cpuinfo_store_boot_cpu(); + save_boot_cpuinfo_data(); /* * We now know enough about the boot CPU to apply the
Move init_cpu_features() ahead of setup_arch()->early_fixmap_init(), which is the preparation work for checking the condition to assign arm64_use_ng_mappings as cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0). Besides, jump_label_init() is also moved ahead because cpus_have_const_cap() depends on static key enable api. Percpu helpers should be avoided in cpuinfo_store_boot_cpu() before percpu init at main.c::setup_per_cpu_areas() Signed-off-by: Jia He <justin.he@arm.com> --- arch/arm64/include/asm/cpu.h | 1 + arch/arm64/kernel/cpuinfo.c | 13 ++++++++++--- arch/arm64/kernel/setup.c | 14 +++++++++----- arch/arm64/kernel/smp.c | 3 +-- 4 files changed, 21 insertions(+), 10 deletions(-)