RISC-V updates for v6.19-rc7

- Fix the RISC-V timer compare register update sequence on RV32
   systems to use the recommended sequence in the RISC-V ISA manual.
   This avoids spurious interrupts during updates.
 
 - Add a dependence on the new CONFIG_CACHEMAINT_FOR_DMA Kconfig symbol
   for Renesas and StarFive RISC-V SoCs
 
 - Add a temporary workaround for a Clang compiler bug caused by using
   asm_goto_output for get_user()
 
 - Clarify our documentation to specifically state a particular ISA
   specification version for a chapter number reference
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Merge tag 'riscv-for-linus-6.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Paul Walmsley:
 "The notable changes here are the three RISC-V timer compare register
  update sequence patches. These only apply to RV32 systems and are
  related to the 64-bit timer compare value being split across two
  separate 32-bit registers.

  We weren't using the appropriate three-write sequence, documented in
  the RISC-V ISA specifications, to avoid spurious timer interrupts
  during the update sequence; so, these patches now use the recommended
  sequence.

  This doesn't affect 64-bit RISC-V systems, since the timer compare
  value fits inside a single register and can be updated with a single
  write.

   - Fix the RISC-V timer compare register update sequence on RV32
     systems to use the recommended sequence in the RISC-V ISA manual

     This avoids spurious interrupts during updates

   - Add a dependence on the new CONFIG_CACHEMAINT_FOR_DMA Kconfig
     symbol for Renesas and StarFive RISC-V SoCs

   - Add a temporary workaround for a Clang compiler bug caused by using
     asm_goto_output for get_user()

   - Clarify our documentation to specifically state a particular ISA
     specification version for a chapter number reference"

* tag 'riscv-for-linus-6.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Add intermediate cast to 'unsigned long' in __get_user_asm
  riscv: Use 64-bit variable for output in __get_user_asm
  soc: renesas: Fix missing dependency on new CONFIG_CACHEMAINT_FOR_DMA
  riscv: ERRATA_STARFIVE_JH7100: Fix missing dependency on new CONFIG_CACHEMAINT_FOR_DMA
  riscv: suspend: Fix stimecmp update hazard on RV32
  riscv: kvm: Fix vstimecmp update hazard on RV32
  riscv: clocksource: Fix stimecmp update hazard on RV32
  Documentation: riscv: uabi: Clarify ISA spec version for canonical order

Documentation/arch/riscv/uabi.rst

@@ -7,7 +7,9 @@ ISA string ordering in /proc/cpuinfo
 ------------------------------------
 
 The canonical order of ISA extension names in the ISA string is defined in
-chapter 27 of the unprivileged specification.
+Chapter 27 of the RISC-V Instruction Set Manual Volume I Unprivileged ISA
+(Document Version 20191213).
+
 The specification uses vague wording, such as should, when it comes to ordering,
 so for our purposes the following rules apply:
 

arch/riscv/Kconfig.errata

@@ -84,6 +84,7 @@ config ERRATA_STARFIVE_JH7100
 	select DMA_GLOBAL_POOL
 	select RISCV_DMA_NONCOHERENT
 	select RISCV_NONSTANDARD_CACHE_OPS
+	select CACHEMAINT_FOR_DMA
 	select SIFIVE_CCACHE
 	default n
 	help

arch/riscv/include/asm/uaccess.h

@@ -97,13 +97,23 @@ static inline unsigned long __untagged_addr_remote(struct mm_struct *mm, unsigne
  */
 
 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
+/*
+ * Use a temporary variable for the output of the asm goto to avoid a
+ * triggering an LLVM assertion due to sign extending the output when
+ * it is used in later function calls:
+ * https://github.com/llvm/llvm-project/issues/143795
+ */
 #define __get_user_asm(insn, x, ptr, label)			\
+do {								\
+	u64 __tmp;						\
 	asm_goto_output(					\
 		"1:\n"						\
 		"	" insn " %0, %1\n"			\
 		_ASM_EXTABLE_UACCESS_ERR(1b, %l2, %0)		\
-		: "=&r" (x)					\
-		: "m" (*(ptr)) : : label)
+		: "=&r" (__tmp)					\
+		: "m" (*(ptr)) : : label);			\
+	(x) = (__typeof__(x))(unsigned long)__tmp;		\
+} while (0)
 #else /* !CONFIG_CC_HAS_ASM_GOTO_OUTPUT */
 #define __get_user_asm(insn, x, ptr, label)			\
 do {								\

arch/riscv/kernel/suspend.c

@@ -51,10 +51,11 @@ void suspend_restore_csrs(struct suspend_context *context)
 
 #ifdef CONFIG_MMU
 	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC)) {
-		csr_write(CSR_STIMECMP, context->stimecmp);
 #if __riscv_xlen < 64
+		csr_write(CSR_STIMECMP, ULONG_MAX);
 		csr_write(CSR_STIMECMPH, context->stimecmph);
 #endif
+		csr_write(CSR_STIMECMP, context->stimecmp);
 	}
 
 	csr_write(CSR_SATP, context->satp);

arch/riscv/kvm/vcpu_timer.c

@@ -72,8 +72,9 @@ static int kvm_riscv_vcpu_timer_cancel(struct kvm_vcpu_timer *t)
 static int kvm_riscv_vcpu_update_vstimecmp(struct kvm_vcpu *vcpu, u64 ncycles)
 {
 #if defined(CONFIG_32BIT)
-	ncsr_write(CSR_VSTIMECMP, ncycles & 0xFFFFFFFF);
+	ncsr_write(CSR_VSTIMECMP,  ULONG_MAX);
 	ncsr_write(CSR_VSTIMECMPH, ncycles >> 32);
+	ncsr_write(CSR_VSTIMECMP, (u32)ncycles);
 #else
 	ncsr_write(CSR_VSTIMECMP, ncycles);
 #endif
@@ -307,8 +308,9 @@ void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu)
 		return;
 
 #if defined(CONFIG_32BIT)
-	ncsr_write(CSR_VSTIMECMP, (u32)t->next_cycles);
+	ncsr_write(CSR_VSTIMECMP, ULONG_MAX);
 	ncsr_write(CSR_VSTIMECMPH, (u32)(t->next_cycles >> 32));
+	ncsr_write(CSR_VSTIMECMP, (u32)(t->next_cycles));
 #else
 	ncsr_write(CSR_VSTIMECMP, t->next_cycles);
 #endif

drivers/clocksource/timer-riscv.c

@@ -50,8 +50,9 @@ static int riscv_clock_next_event(unsigned long delta,
 
 	if (static_branch_likely(&riscv_sstc_available)) {
 #if defined(CONFIG_32BIT)
-		csr_write(CSR_STIMECMP, next_tval & 0xFFFFFFFF);
+		csr_write(CSR_STIMECMP, ULONG_MAX);
 		csr_write(CSR_STIMECMPH, next_tval >> 32);
+		csr_write(CSR_STIMECMP, next_tval & 0xFFFFFFFF);
 #else
 		csr_write(CSR_STIMECMP, next_tval);
 #endif

drivers/soc/renesas/Kconfig

@@ -445,6 +445,7 @@ config ARCH_R9A07G043
 	depends on RISCV_SBI
 	select ARCH_RZG2L
 	select AX45MP_L2_CACHE
+	select CACHEMAINT_FOR_DMA
 	select DMA_GLOBAL_POOL
 	select ERRATA_ANDES
 	select ERRATA_ANDES_CMO