Re: [PATCH 1/1] x86/ioremap: Use is_vmalloc_addr in iounmap

[Thomas Gleixner <tglx@linutronix.de>]

On Mon, Aug 12 2024 at 12:03, Thomas Gleixner wrote:
> On Mon, Aug 12 2024 at 17:41, Alistair Popple wrote:
>> The same applies to the rest of the DIRECT_MAP_END users here. Perhaps
>> it would be better to define this as DIRECT_MAP_SIZE and calculate this
>> based off PAGE_OFFSET instead?
>
> Duh, yes. I shouldn't try to write patches at 30C :)

We can avoid the calculation and expose the end of the physical address
space for memory. This time I actually built and ran it :)

Thanks,

        tglx
---
 arch/x86/include/asm/page_64.h          |    1 +
 arch/x86/include/asm/pgtable_64_types.h |    2 ++
 arch/x86/mm/kaslr.c                     |   21 ++++++++++++++++++---
 include/linux/mm.h                      |    4 ++++
 kernel/resource.c                       |    6 ++----
 mm/memory_hotplug.c                     |    2 +-
 mm/sparse.c                             |    2 +-
 7 files changed, 29 insertions(+), 9 deletions(-)

--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -17,6 +17,7 @@ extern unsigned long phys_base;
 extern unsigned long page_offset_base;
 extern unsigned long vmalloc_base;
 extern unsigned long vmemmap_base;
+extern unsigned long physmem_end;
 
 static __always_inline unsigned long __phys_addr_nodebug(unsigned long x)
 {
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -134,10 +134,12 @@ extern unsigned int ptrs_per_p4d;
 # define VMALLOC_START		vmalloc_base
 # define VMALLOC_SIZE_TB	(pgtable_l5_enabled() ? VMALLOC_SIZE_TB_L5 : VMALLOC_SIZE_TB_L4)
 # define VMEMMAP_START		vmemmap_base
+# define PHYSMEM_END		physmem_end
 #else
 # define VMALLOC_START		__VMALLOC_BASE_L4
 # define VMALLOC_SIZE_TB	VMALLOC_SIZE_TB_L4
 # define VMEMMAP_START		__VMEMMAP_BASE_L4
+# define PHYSMEM_END		((1ULL << MAX_PHYSMEM_BITS) - 1)
 #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */
 
 /*
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -47,13 +47,24 @@ static const unsigned long vaddr_end = C
  */
 static __initdata struct kaslr_memory_region {
 	unsigned long *base;
+	unsigned long *end;
 	unsigned long size_tb;
 } kaslr_regions[] = {
-	{ &page_offset_base, 0 },
-	{ &vmalloc_base, 0 },
-	{ &vmemmap_base, 0 },
+	{
+		.base	= &page_offset_base,
+		.end	= &physmem_end,
+	},
+	{
+		.base	= &vmalloc_base,
+	},
+	{
+		.base	= &vmemmap_base,
+	},
 };
 
+/* The end of the possible address space for physical memory */
+unsigned long physmem_end __ro_after_init;
+
 /* Get size in bytes used by the memory region */
 static inline unsigned long get_padding(struct kaslr_memory_region *region)
 {
@@ -82,6 +93,8 @@ void __init kernel_randomize_memory(void
 	BUILD_BUG_ON(vaddr_end != CPU_ENTRY_AREA_BASE);
 	BUILD_BUG_ON(vaddr_end > __START_KERNEL_map);
 
+	/* Preset the end of the possible address space for physical memory */
+	physmem_end = ((1ULL << MAX_PHYSMEM_BITS) - 1);
 	if (!kaslr_memory_enabled())
 		return;
 
@@ -134,6 +147,8 @@ void __init kernel_randomize_memory(void
 		 */
 		vaddr += get_padding(&kaslr_regions[i]);
 		vaddr = round_up(vaddr + 1, PUD_SIZE);
+		if (kaslr_regions[i].end)
+			*kaslr_regions[i].end = __pa(vaddr) - 1;
 		remain_entropy -= entropy;
 	}
 }
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -97,6 +97,10 @@ extern const int mmap_rnd_compat_bits_ma
 extern int mmap_rnd_compat_bits __read_mostly;
 #endif
 
+#ifndef PHYSMEM_END
+# define PHYSMEM_END	(1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT))
+#endif
+
 #include <asm/page.h>
 #include <asm/processor.h>
 
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1826,8 +1826,7 @@ static resource_size_t gfr_start(struct
 	if (flags & GFR_DESCENDING) {
 		resource_size_t end;
 
-		end = min_t(resource_size_t, base->end,
-			    (1ULL << MAX_PHYSMEM_BITS) - 1);
+		end = min_t(resource_size_t, base->end, PHYSMEM_END);
 		return end - size + 1;
 	}
 
@@ -1844,8 +1843,7 @@ static bool gfr_continue(struct resource
 	 * @size did not wrap 0.
 	 */
 	return addr > addr - size &&
-	       addr <= min_t(resource_size_t, base->end,
-			     (1ULL << MAX_PHYSMEM_BITS) - 1);
+	       addr <= min_t(resource_size_t, base->end, PHYSMEM_END);
 }
 
 static resource_size_t gfr_next(resource_size_t addr, resource_size_t size,
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1681,7 +1681,7 @@ struct range __weak arch_get_mappable_ra
 
 struct range mhp_get_pluggable_range(bool need_mapping)
 {
-	const u64 max_phys = (1ULL << MAX_PHYSMEM_BITS) - 1;
+	const u64 max_phys = PHYSMEM_END;
 	struct range mhp_range;
 
 	if (need_mapping) {
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -129,7 +129,7 @@ static inline int sparse_early_nid(struc
 static void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
 						unsigned long *end_pfn)
 {
-	unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
+	unsigned long max_sparsemem_pfn = (PHYSMEM_END + 1) >> PAGE_SHIFT;
 
 	/*
 	 * Sanity checks - do not allow an architecture to pass