RISC-V Fixes for 5.7-rc6

This consists of a handful of build fixes, all found by Huawei's autobuilder.
 None of these patches should have any functional impact on kernels that build,
 and they're mostly related to various features intermingling with !MMU.  While
 some of these might be better hoisted to generic code, it seems better to have
 the simple fixes in the meanwhile.
 
 As far as I know these are the only outstanding patches for 5.7.
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Merge tag 'riscv-for-linus-5.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Palmer Dabbelt:
 "A handful of build fixes, all found by Huawei's autobuilder.

  None of these patches should have any functional impact on kernels
  that build, and they're mostly related to various features
  intermingling with !MMU.

  While some of these might be better hoisted to generic code, it seems
  better to have the simple fixes in the meanwhile.

  As far as I know these are the only outstanding patches for 5.7"

* tag 'riscv-for-linus-5.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: mmiowb: Fix implicit declaration of function 'smp_processor_id'
  riscv: pgtable: Fix __kernel_map_pages build error if NOMMU
  riscv: Make SYS_SUPPORTS_HUGETLBFS depends on MMU
  riscv: Disable ARCH_HAS_DEBUG_VIRTUAL if NOMMU
  riscv: Add pgprot_writecombine/device and PAGE_SHARED defination if NOMMU
  riscv: stacktrace: Fix undefined reference to `walk_stackframe'
  riscv: Fix unmet direct dependencies built based on SOC_VIRT
  riscv: perf: RISCV_BASE_PMU should be independent
  riscv: perf_event: Make some funciton static

arch/riscv/Kconfig

@@ -54,7 +54,7 @@ config RISCV
 	select GENERIC_ARCH_TOPOLOGY if SMP
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_MMIOWB
-	select ARCH_HAS_DEBUG_VIRTUAL
+	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select HAVE_EBPF_JIT if MMU
 	select EDAC_SUPPORT
 	select ARCH_HAS_GIGANTIC_PAGE
@@ -136,6 +136,7 @@ config ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	def_bool y
 
 config SYS_SUPPORTS_HUGETLBFS
+	depends on MMU
 	def_bool y
 
 config STACKTRACE_SUPPORT

arch/riscv/Kconfig.socs

@@ -11,14 +11,15 @@ config SOC_SIFIVE
 	  This enables support for SiFive SoC platform hardware.
 
 config SOC_VIRT
-       bool "QEMU Virt Machine"
-       select POWER_RESET_SYSCON
-       select POWER_RESET_SYSCON_POWEROFF
-       select GOLDFISH
-       select RTC_DRV_GOLDFISH
-       select SIFIVE_PLIC
-       help
-         This enables support for QEMU Virt Machine.
+	bool "QEMU Virt Machine"
+	select POWER_RESET
+	select POWER_RESET_SYSCON
+	select POWER_RESET_SYSCON_POWEROFF
+	select GOLDFISH
+	select RTC_DRV_GOLDFISH if RTC_CLASS
+	select SIFIVE_PLIC
+	help
+	  This enables support for QEMU Virt Machine.
 
 config SOC_KENDRYTE
 	bool "Kendryte K210 SoC"

arch/riscv/include/asm/mmio.h

@@ -16,6 +16,8 @@
 
 #ifndef CONFIG_MMU
 #define pgprot_noncached(x)	(x)
+#define pgprot_writecombine(x)	(x)
+#define pgprot_device(x)	(x)
 #endif /* CONFIG_MMU */
 
 /* Generic IO read/write.  These perform native-endian accesses. */

arch/riscv/include/asm/mmiowb.h

@@ -9,6 +9,7 @@
  */
 #define mmiowb()	__asm__ __volatile__ ("fence o,w" : : : "memory");
 
+#include <linux/smp.h>
 #include <asm-generic/mmiowb.h>
 
 #endif	/* _ASM_RISCV_MMIOWB_H */

arch/riscv/include/asm/perf_event.h

@@ -12,19 +12,14 @@
 #include <linux/ptrace.h>
 #include <linux/interrupt.h>
 
+#ifdef CONFIG_RISCV_BASE_PMU
 #define RISCV_BASE_COUNTERS	2
 
 /*
  * The RISCV_MAX_COUNTERS parameter should be specified.
  */
 
-#ifdef CONFIG_RISCV_BASE_PMU
 #define RISCV_MAX_COUNTERS	2
-#endif
-
-#ifndef RISCV_MAX_COUNTERS
-#error "Please provide a valid RISCV_MAX_COUNTERS for the PMU."
-#endif
 
 /*
  * These are the indexes of bits in counteren register *minus* 1,
@@ -82,6 +77,7 @@ struct riscv_pmu {
 	int		irq;
 };
 
+#endif
 #ifdef CONFIG_PERF_EVENTS
 #define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
 #endif

arch/riscv/include/asm/pgtable.h

@@ -470,12 +470,15 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 
 #else /* CONFIG_MMU */
 
+#define PAGE_SHARED		__pgprot(0)
 #define PAGE_KERNEL		__pgprot(0)
 #define swapper_pg_dir		NULL
 #define VMALLOC_START		0
 
 #define TASK_SIZE 0xffffffffUL
 
+static inline void __kernel_map_pages(struct page *page, int numpages, int enable) {}
+
 #endif /* !CONFIG_MMU */
 
 #define kern_addr_valid(addr)   (1) /* FIXME */

arch/riscv/kernel/Makefile

@@ -43,7 +43,7 @@ obj-$(CONFIG_MODULE_SECTIONS)	+= module-sections.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o
 obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
 
-obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o
+obj-$(CONFIG_RISCV_BASE_PMU)	+= perf_event.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
 obj-$(CONFIG_RISCV_SBI)		+= sbi.o

arch/riscv/kernel/perf_event.c

@@ -147,7 +147,7 @@ static int riscv_map_hw_event(u64 config)
 	return riscv_pmu->hw_events[config];
 }
 
-int riscv_map_cache_decode(u64 config, unsigned int *type,
+static int riscv_map_cache_decode(u64 config, unsigned int *type,
 			   unsigned int *op, unsigned int *result)
 {
 	return -ENOENT;
@@ -342,7 +342,7 @@ static void riscv_pmu_del(struct perf_event *event, int flags)
 
 static DEFINE_MUTEX(pmc_reserve_mutex);
 
-irqreturn_t riscv_base_pmu_handle_irq(int irq_num, void *dev)
+static irqreturn_t riscv_base_pmu_handle_irq(int irq_num, void *dev)
 {
 	return IRQ_NONE;
 }
@@ -361,7 +361,7 @@ static int reserve_pmc_hardware(void)
 	return err;
 }
 
-void release_pmc_hardware(void)
+static void release_pmc_hardware(void)
 {
 	mutex_lock(&pmc_reserve_mutex);
 	if (riscv_pmu->irq >= 0)
@@ -464,7 +464,7 @@ static const struct of_device_id riscv_pmu_of_ids[] = {
 	{ /* sentinel value */ }
 };
 
-int __init init_hw_perf_events(void)
+static int __init init_hw_perf_events(void)
 {
 	struct device_node *node = of_find_node_by_type(NULL, "pmu");
 	const struct of_device_id *of_id;

arch/riscv/kernel/stacktrace.c

@@ -65,7 +65,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 
 #else /* !CONFIG_FRAME_POINTER */
 
-static void notrace walk_stackframe(struct task_struct *task,
+void notrace walk_stackframe(struct task_struct *task,
 	struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
 {
 	unsigned long sp, pc;