riscv: kdump: use generic interface to simplify crashkernel reservation

With the help of newly changed function parse_crashkernel() and generic
reserve_crashkernel_generic(), crashkernel reservation can be simplified
by steps:

1) Add a new header file <asm/crash_core.h>, and define CRASH_ALIGN,
   CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
   DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;

2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
   reserve_crashkernel_generic();

3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
   arch/riscv/Kconfig.

The old reserve_crashkernel_low() and reserve_crashkernel() can be
removed.

[chenjiahao16@huawei.com: fix crashkernel reserving problem on RISC-V]
  Link: https://lkml.kernel.org/r/20230925024333.730964-1-chenjiahao16@huawei.com
Link: https://lkml.kernel.org/r/20230914033142.676708-9-bhe@redhat.comSigned-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Jiahao <chenjiahao16@huawei.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/riscv/Kconfig

@@ -694,6 +694,9 @@ config ARCH_SUPPORTS_KEXEC_PURGATORY
 config ARCH_SUPPORTS_CRASH_DUMP
 	def_bool y
 
+config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+	def_bool CRASH_CORE
+
 config COMPAT
 	bool "Kernel support for 32-bit U-mode"
 	default 64BIT

arch/riscv/include/asm/crash_core.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _RISCV_CRASH_CORE_H
+#define _RISCV_CRASH_CORE_H
+
+#define CRASH_ALIGN			PMD_SIZE
+
+#define CRASH_ADDR_LOW_MAX		dma32_phys_limit
+#define CRASH_ADDR_HIGH_MAX		memblock_end_of_DRAM()
+
+extern phys_addr_t memblock_end_of_DRAM(void);
+#endif

arch/riscv/include/asm/processor.h

@@ -116,6 +116,8 @@ static inline void wait_for_interrupt(void)
 	__asm__ __volatile__ ("wfi");
 }
 
+extern phys_addr_t dma32_phys_limit;
+
 struct device_node;
 int riscv_of_processor_hartid(struct device_node *node, unsigned long *hartid);
 int riscv_early_of_processor_hartid(struct device_node *node, unsigned long *hartid);

arch/riscv/kernel/setup.c

@@ -173,19 +173,6 @@ static void __init init_resources(void)
 	if (ret < 0)
 		goto error;
 
-#ifdef CONFIG_KEXEC_CORE
-	if (crashk_res.start != crashk_res.end) {
-		ret = add_resource(&iomem_resource, &crashk_res);
-		if (ret < 0)
-			goto error;
-	}
-	if (crashk_low_res.start != crashk_low_res.end) {
-		ret = add_resource(&iomem_resource, &crashk_low_res);
-		if (ret < 0)
-			goto error;
-	}
-#endif
-
 #ifdef CONFIG_CRASH_DUMP
 	if (elfcorehdr_size > 0) {
 		elfcorehdr_res.start = elfcorehdr_addr;

arch/riscv/mm/init.c

@@ -65,7 +65,7 @@ extern char _start[];
 void *_dtb_early_va __initdata;
 uintptr_t _dtb_early_pa __initdata;
 
-static phys_addr_t dma32_phys_limit __initdata;
+phys_addr_t dma32_phys_limit __initdata;
 
 static void __init zone_sizes_init(void)
 {
@@ -1333,28 +1333,6 @@ static inline void setup_vm_final(void)
 }
 #endif /* CONFIG_MMU */
 
-/* Reserve 128M low memory by default for swiotlb buffer */
-#define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
-
-static int __init reserve_crashkernel_low(unsigned long long low_size)
-{
-	unsigned long long low_base;
-
-	low_base = memblock_phys_alloc_range(low_size, PMD_SIZE, 0, dma32_phys_limit);
-	if (!low_base) {
-		pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size);
-		return -ENOMEM;
-	}
-
-	pr_info("crashkernel low memory reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
-		low_base, low_base + low_size, low_size >> 20);
-
-	crashk_low_res.start = low_base;
-	crashk_low_res.end = low_base + low_size - 1;
-
-	return 0;
-}
-
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *
@@ -1362,122 +1340,25 @@ static int __init reserve_crashkernel_low(unsigned long long low_size)
  * line parameter. The memory reserved is used by dump capture kernel when
  * primary kernel is crashing.
  */
-static void __init reserve_crashkernel(void)
+static void __init arch_reserve_crashkernel(void)
 {
-	unsigned long long crash_base = 0;
-	unsigned long long crash_size = 0;
-	unsigned long long crash_low_size = 0;
-	unsigned long search_start = memblock_start_of_DRAM();
-	unsigned long search_end = (unsigned long)dma32_phys_limit;
+	unsigned long long low_size = 0;
+	unsigned long long crash_base, crash_size;
 	char *cmdline = boot_command_line;
-	bool fixed_base = false;
 	bool high = false;
-
-	int ret = 0;
+	int ret;
 
 	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
 		return;
-	/*
-	 * Don't reserve a region for a crash kernel on a crash kernel
-	 * since it doesn't make much sense and we have limited memory
-	 * resources.
-	 */
-	if (is_kdump_kernel()) {
-		pr_info("crashkernel: ignoring reservation request\n");
-		return;
-	}
 
 	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
-				&crash_size, &crash_base, NULL, NULL);
-	if (ret == -ENOENT) {
-		/* Fallback to crashkernel=X,[high,low] */
-		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);
-		if (ret || !crash_size)
-			return;
-
-		/*
-		 * crashkernel=Y,low is valid only when crashkernel=X,high
-		 * is passed.
-		 */
-		ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base);
-		if (ret == -ENOENT)
-			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
-		else if (ret)
-			return;
-
-		search_start = (unsigned long)dma32_phys_limit;
-		search_end = memblock_end_of_DRAM();
-		high = true;
-	} else if (ret || !crash_size) {
-		/* Invalid argument value specified */
-		return;
-	}
-
-	crash_size = PAGE_ALIGN(crash_size);
-
-	if (crash_base) {
-		fixed_base = true;
-		search_start = crash_base;
-		search_end = crash_base + crash_size;
-	}
-
-	/*
-	 * Current riscv boot protocol requires 2MB alignment for
-	 * RV64 and 4MB alignment for RV32 (hugepage size)
-	 *
-	 * Try to alloc from 32bit addressible physical memory so that
-	 * swiotlb can work on the crash kernel.
-	 */
-	crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
-					       search_start, search_end);
-	if (crash_base == 0) {
-		/*
-		 * For crashkernel=size[KMG]@offset[KMG], print out failure
-		 * message if can't reserve the specified region.
-		 */
-		if (fixed_base) {
-			pr_warn("crashkernel: allocating failed with given size@offset\n");
-			return;
-		}
-
-		if (high) {
-			/*
-			 * For crashkernel=size[KMG],high, if the first attempt was
-			 * for high memory, fall back to low memory.
-			 */
-			search_start = memblock_start_of_DRAM();
-			search_end = (unsigned long)dma32_phys_limit;
-		} else {
-			/*
-			 * For crashkernel=size[KMG], if the first attempt was for
-			 * low memory, fall back to high memory, the minimum required
-			 * low memory will be reserved later.
-			 */
-			search_start = (unsigned long)dma32_phys_limit;
-			search_end = memblock_end_of_DRAM();
-			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
-		}
-
-		crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
-						       search_start, search_end);
-		if (crash_base == 0) {
-			pr_warn("crashkernel: couldn't allocate %lldKB\n",
-				crash_size >> 10);
+				&crash_size, &crash_base,
+				&low_size, &high);
+	if (ret)
 		return;
-		}
-	}
-
-	if ((crash_base >= dma32_phys_limit) && crash_low_size &&
-	     reserve_crashkernel_low(crash_low_size)) {
-		memblock_phys_free(crash_base, crash_size);
-		return;
-	}
-
-	pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n",
-		crash_base, crash_base + crash_size, crash_size >> 20);
 
-	crashk_res.start = crash_base;
-	crashk_res.end = crash_base + crash_size - 1;
+	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
+				    low_size, high);
 }
 
 void __init paging_init(void)
@@ -1495,7 +1376,7 @@ void __init misc_mem_init(void)
 	arch_numa_init();
 	sparse_init();
 	zone_sizes_init();
-	reserve_crashkernel();
+	arch_reserve_crashkernel();
 	memblock_dump_all();
 }