Merge patch series "Zacas/Zabha support and qspinlocks"

Alexandre Ghiti <alexghiti@rivosinc.com> says:

This implements [cmp]xchgXX() macros using Zacas and Zabha extensions
and finally uses those newly introduced macros to add support for
qspinlocks: note that this implementation of qspinlocks satisfies the
forward progress guarantee.

It also uses Ziccrse to provide the qspinlock implementation.

Thanks to Guo and Leonardo for their work!

* b4-shazam-merge: (1314 commits)
  riscv: Add qspinlock support
  dt-bindings: riscv: Add Ziccrse ISA extension description
  riscv: Add ISA extension parsing for Ziccrse
  asm-generic: ticket-lock: Add separate ticket-lock.h
  asm-generic: ticket-lock: Reuse arch_spinlock_t of qspinlock
  riscv: Implement xchg8/16() using Zabha
  riscv: Implement arch_cmpxchg128() using Zacas
  riscv: Improve zacas fully-ordered cmpxchg()
  riscv: Implement cmpxchg8/16() using Zabha
  dt-bindings: riscv: Add Zabha ISA extension description
  riscv: Implement cmpxchg32/64() using Zacas
  riscv: Do not fail to build on byte/halfword operations with Zawrs
  riscv: Move cpufeature.h macros into their own header

Link: https://lore.kernel.org/r/20241103145153.105097-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

1 files changed, 70 insertions, 2 deletions

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index bdc93178917e..5bdda86ada37 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -82,6 +82,7 @@ config RISCV
 	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 	select ARCH_WANTS_NO_INSTR
 	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
+	select ARCH_WEAK_RELEASE_ACQUIRE if ARCH_USE_QUEUED_SPINLOCKS
 	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
 	select BUILDTIME_TABLE_SORT if MMU
 	select CLINT_TIMER if RISCV_M_MODE
@@ -115,6 +116,7 @@ config RISCV
 	select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
 	select HARDIRQS_SW_RESEND
 	select HAS_IOPORT if MMU
+	select HAVE_ALIGNED_STRUCT_PAGE
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMALLOC if HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_HUGE_VMAP if MMU && 64BIT
@@ -506,6 +508,39 @@ config NODES_SHIFT
 	  Specify the maximum number of NUMA Nodes available on the target
 	  system.  Increases memory reserved to accommodate various tables.
 
+choice
+	prompt "RISC-V spinlock type"
+	default RISCV_COMBO_SPINLOCKS
+
+config RISCV_TICKET_SPINLOCKS
+	bool "Using ticket spinlock"
+
+config RISCV_QUEUED_SPINLOCKS
+	bool "Using queued spinlock"
+	depends on SMP && MMU && NONPORTABLE
+	select ARCH_USE_QUEUED_SPINLOCKS
+	help
+	  The queued spinlock implementation requires the forward progress
+	  guarantee of cmpxchg()/xchg() atomic operations: CAS with Zabha or
+	  LR/SC with Ziccrse provide such guarantee.
+
+	  Select this if and only if Zabha or Ziccrse is available on your
+	  platform, RISCV_QUEUED_SPINLOCKS must not be selected for platforms
+	  without one of those extensions.
+
+	  If unsure, select RISCV_COMBO_SPINLOCKS, which will use qspinlocks
+	  when supported and otherwise ticket spinlocks.
+
+config RISCV_COMBO_SPINLOCKS
+	bool "Using combo spinlock"
+	depends on SMP && MMU
+	select ARCH_USE_QUEUED_SPINLOCKS
+	help
+	  Embed both queued spinlock and ticket lock so that the spinlock
+	  implementation can be chosen at runtime.
+
+endchoice
+
 config RISCV_ALTERNATIVE
 	bool
 	depends on !XIP_KERNEL
@@ -643,6 +678,40 @@ config RISCV_ISA_ZAWRS
 	  use of these instructions in the kernel when the Zawrs extension is
 	  detected at boot.
 
+config TOOLCHAIN_HAS_ZABHA
+	bool
+	default y
+	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zabha)
+	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zabha)
+	depends on AS_HAS_OPTION_ARCH
+
+config RISCV_ISA_ZABHA
+	bool "Zabha extension support for atomic byte/halfword operations"
+	depends on TOOLCHAIN_HAS_ZABHA
+	depends on RISCV_ALTERNATIVE
+	default y
+	help
+	  Enable the use of the Zabha ISA-extension to implement kernel
+	  byte/halfword atomic memory operations when it is detected at boot.
+
+	  If you don't know what to do here, say Y.
+
+config TOOLCHAIN_HAS_ZACAS
+	bool
+	default y
+	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zacas)
+	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zacas)
+	depends on AS_HAS_OPTION_ARCH
+
+config RISCV_ISA_ZACAS
+	bool "Zacas extension support for atomic CAS"
+	depends on TOOLCHAIN_HAS_ZACAS
+	depends on RISCV_ALTERNATIVE
+	default y
+	help
+	  Enable the use of the Zacas ISA-extension to implement kernel atomic
+	  cmpxchg operations when it is detected at boot.
+
 	  If you don't know what to do here, say Y.
 
 config TOOLCHAIN_HAS_ZBB
@@ -788,8 +857,7 @@ config IRQ_STACKS
 config THREAD_SIZE_ORDER
 	int "Kernel stack size (in power-of-two numbers of page size)" if VMAP_STACK && EXPERT
 	range 0 4
-	default 1 if 32BIT && !KASAN
-	default 3 if 64BIT && KASAN
+	default 1 if 32BIT
 	default 2
 	help
 	  Specify the Pages of thread stack size (from 4KB to 64KB), which also