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Subject[tip: x86/mm] x86/kasan: Add helpers to align shadow addresses up and down
The following commit has been merged into the x86/mm branch of tip:

Commit-ID: 74b5a69c2a577d4fdba581171e3ebf33cddbddc1
Gitweb: https://git.kernel.org/tip/74b5a69c2a577d4fdba581171e3ebf33cddbddc1
Author: Sean Christopherson <seanjc@google.com>
AuthorDate: Thu, 10 Nov 2022 20:35:03
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 15 Nov 2022 22:29:59 +01:00

x86/kasan: Add helpers to align shadow addresses up and down

Add helpers to dedup code for aligning shadow address up/down to page
boundaries when translating an address to its shadow.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Link: https://lkml.kernel.org/r/20221110203504.1985010-5-seanjc@google.com
---
arch/x86/mm/kasan_init_64.c | 40 +++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 18 deletions(-)

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index ad7872a..afc5e12 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -316,22 +316,33 @@ void __init kasan_early_init(void)
kasan_map_early_shadow(init_top_pgt);
}

+static unsigned long kasan_mem_to_shadow_align_down(unsigned long va)
+{
+ unsigned long shadow = (unsigned long)kasan_mem_to_shadow((void *)va);
+
+ return round_down(shadow, PAGE_SIZE);
+}
+
+static unsigned long kasan_mem_to_shadow_align_up(unsigned long va)
+{
+ unsigned long shadow = (unsigned long)kasan_mem_to_shadow((void *)va);
+
+ return round_up(shadow, PAGE_SIZE);
+}
+
void __init kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid)
{
unsigned long shadow_start, shadow_end;

- shadow_start = (unsigned long)kasan_mem_to_shadow(va);
- shadow_start = round_down(shadow_start, PAGE_SIZE);
- shadow_end = (unsigned long)kasan_mem_to_shadow(va + size);
- shadow_end = round_up(shadow_end, PAGE_SIZE);
-
+ shadow_start = kasan_mem_to_shadow_align_down((unsigned long)va);
+ shadow_end = kasan_mem_to_shadow_align_up((unsigned long)va + size);
kasan_populate_shadow(shadow_start, shadow_end, nid);
}

void __init kasan_init(void)
{
+ unsigned long shadow_cea_begin, shadow_cea_end;
int i;
- void *shadow_cea_begin, *shadow_cea_end;

memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));

@@ -372,16 +383,9 @@ void __init kasan_init(void)
map_range(&pfn_mapped[i]);
}

- shadow_cea_begin = (void *)CPU_ENTRY_AREA_BASE;
- shadow_cea_begin = kasan_mem_to_shadow(shadow_cea_begin);
- shadow_cea_begin = (void *)round_down(
- (unsigned long)shadow_cea_begin, PAGE_SIZE);
-
- shadow_cea_end = (void *)(CPU_ENTRY_AREA_BASE +
- CPU_ENTRY_AREA_MAP_SIZE);
- shadow_cea_end = kasan_mem_to_shadow(shadow_cea_end);
- shadow_cea_end = (void *)round_up(
- (unsigned long)shadow_cea_end, PAGE_SIZE);
+ shadow_cea_begin = kasan_mem_to_shadow_align_down(CPU_ENTRY_AREA_BASE);
+ shadow_cea_end = kasan_mem_to_shadow_align_up(CPU_ENTRY_AREA_BASE +
+ CPU_ENTRY_AREA_MAP_SIZE);

kasan_populate_early_shadow(
kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
@@ -403,9 +407,9 @@ void __init kasan_init(void)

kasan_populate_early_shadow(
kasan_mem_to_shadow((void *)VMALLOC_END + 1),
- shadow_cea_begin);
+ (void *)shadow_cea_begin);

- kasan_populate_early_shadow(shadow_cea_end,
+ kasan_populate_early_shadow((void *)shadow_cea_end,
kasan_mem_to_shadow((void *)__START_KERNEL_map));

kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
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