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

Thomas Gleixner
2024-08-12T13:23:21Z

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