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Kernel: Fix page round wrap detection for 64-bit

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We were assuming 32-bit pointers, which will not always be the case
Also fixed an incorrect comment about wrapping
This commit is contained in:
Hendiadyoin1 2021-06-28 18:58:23 +02:00 • committed by Andreas Kling
parent 65566d6868
commit 10728cd421
1 changed files with 2 additions and 2 deletions
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4
Kernel/VM/MemoryManager.h
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@ -22,13 +22,13 @@ namespace Kernel {
constexpr bool page_round_up_would_wrap(FlatPtr x) constexpr bool page_round_up_would_wrap(FlatPtr x)
{ {
return x > 0xfffff000u; return x > (explode_byte(0xFF) & ~0xFFF);
} }
constexpr FlatPtr page_round_up(FlatPtr x) constexpr FlatPtr page_round_up(FlatPtr x)
{ {
FlatPtr rounded = (((FlatPtr)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1)); FlatPtr rounded = (((FlatPtr)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1));
// Rounding up >0xffff0000 wraps back to 0. That's never what we want. // Rounding up >0xfffff000 wraps back to 0. That's never what we want.
VERIFY(x == 0 || rounded != 0); VERIFY(x == 0 || rounded != 0);
return rounded; return rounded;
} }