Mark Rutland 54c8818aa2 arm64: Avoid cpus_have_const_cap() for ARM64_HAS_CNP ... In system_supports_cnp() we use cpus_have_const_cap() to check for ARM64_HAS_CNP, but this is only necessary so that the cpu_enable_cnp() callback can run prior to alternatives being patched, and otherwise this is not necessary and alternative_has_cap_*() would be preferable. For historical reasons, cpus_have_const_cap() is more complicated than it needs to be. Before cpucaps are finalized, it will perform a bitmap test of the system_cpucaps bitmap, and once cpucaps are finalized it will use an alternative branch. This used to be necessary to handle some race conditions in the window between cpucap detection and the subsequent patching of alternatives and static branches, where different branches could be out-of-sync with one another (or w.r.t. alternative sequences). Now that we use alternative branches instead of static branches, these are all patched atomically w.r.t. one another, and there are only a handful of cases that need special care in the window between cpucap detection and alternative patching. Due to the above, it would be nice to remove cpus_have_const_cap(), and migrate callers over to alternative_has_cap_*(), cpus_have_final_cap(), or cpus_have_cap() depending on when their requirements. This will remove redundant instructions and improve code generation, and will make it easier to determine how each callsite will behave before, during, and after alternative patching. The cpu_enable_cnp() callback is run immediately after the ARM64_HAS_CNP cpucap is detected system-wide under setup_system_capabilities(), prior to alternatives being patched. During this window cpu_enable_cnp() uses cpu_replace_ttbr1() to set the CNP bit for the swapper_pg_dir in TTBR1. No other users of the ARM64_HAS_CNP cpucap need the up-to-date value during this window: * As KVM isn't initialized yet, kvm_get_vttbr() isn't reachable. * As cpuidle isn't initialized yet, __cpu_suspend_exit() isn't reachable. * At this point all CPUs are using the swapper_pg_dir with a reserved ASID in TTBR1, and the idmap_pg_dir in TTBR0, so neither check_and_switch_context() nor cpu_do_switch_mm() need to do anything special. This patch replaces the use of cpus_have_const_cap() with alternative_has_cap_unlikely(), which will avoid generating code to test the system_cpucaps bitmap and should be better for all subsequent calls at runtime. To allow cpu_enable_cnp() to function prior to alternatives being patched, cpu_replace_ttbr1() is split into cpu_replace_ttbr1() and cpu_enable_swapper_cnp(), with the former only used for early TTBR1 replacement, and the latter used by both cpu_enable_cnp() and __cpu_suspend_exit(). Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Vladimir Murzin <vladimir.murzin@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>		2023-10-16 14:17:04 +01:00
..
pi
probes
vdso
vdso32
.gitignore
acpi.c
acpi_numa.c
acpi_parking_protocol.c
alternative.c
armv8_deprecated.c
asm-offsets.c
cacheinfo.c
compat_alignment.c
cpu-reset.S
cpu_errata.c
cpu_ops.c
cpufeature.c	arm64: Avoid cpus_have_const_cap() for ARM64_HAS_CNP	2023-10-16 14:17:04 +01:00
cpuidle.c
cpuinfo.c
crash_core.c
crash_dump.c
debug-monitors.c
efi-header.S
efi-rt-wrapper.S
efi.c	arm64: Avoid cpus_have_const_cap() for ARM64_HAS_BTI	2023-10-16 14:17:04 +01:00
elfcore.c
entry-common.c
entry-fpsimd.S
entry-ftrace.S
entry.S
fpsimd.c	arm64: Use a positive cpucap for FP/SIMD	2023-10-16 14:17:03 +01:00
ftrace.c
head.S
hibernate-asm.S
hibernate.c
hw_breakpoint.c
hyp-stub.S
idle.c
idreg-override.c
image-vars.h
image.h
io.c
irq.c
jump_label.c
kaslr.c
kexec_image.c
kgdb.c
kuser32.S
machine_kexec.c
machine_kexec_file.c
Makefile
module-plts.c
module.c
mte.c
paravirt.c
patch-scs.c
patching.c
pci.c
perf_callchain.c
perf_regs.c
pointer_auth.c
process.c
proton-pack.c
psci.c
ptrace.c
reloc_test_core.c
reloc_test_syms.S
relocate_kernel.S
return_address.c
sdei.c
setup.c
signal.c
signal32.c
sigreturn32.S
sleep.S
smccc-call.S
smp.c
smp_spin_table.c
stacktrace.c
suspend.c	arm64: Avoid cpus_have_const_cap() for ARM64_HAS_CNP	2023-10-16 14:17:04 +01:00
sys.c
sys32.c
sys_compat.c
syscall.c
time.c
topology.c
trace-events-emulation.h
traps.c
vdso-wrap.S
vdso.c	arm64: Avoid cpus_have_const_cap() for ARM64_HAS_BTI	2023-10-16 14:17:04 +01:00
vdso32-wrap.S
vmlinux.lds.S
watchdog_hld.c