diff options
| author | Kornel Dulęba <korneld@google.com> | 2025-04-17 11:47:54 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-04-29 16:17:58 +0100 |
| commit | f101c56447717c595d803894ba0e215f56c6fba4 (patch) | |
| tree | b9a8ecc254883a2e4d01c7b3b61249940f29313e | |
| parent | 1db780bafa4cedd20f040c3fce616e47aa7c0c47 (diff) | |
arm64: Support ARM64_VA_BITS=52 when setting ARCH_MMAP_RND_BITS_MAX
When the 52-bit virtual addressing was introduced the select like
ARCH_MMAP_RND_BITS_MAX logic was never updated to account for it.
Because of that the rnd max bits knob is set to the default value of 18
when ARM64_VA_BITS=52.
Fix this by setting ARCH_MMAP_RND_BITS_MAX to the same value that would
be used if 48-bit addressing was used. Higher values can't used here
because 52-bit addressing is used only if the caller provides a hint to
mmap, with a fallback to 48-bit. The knob in question is an upper bound
for what the user can set in /proc/sys/vm/mmap_rnd_bits, which in turn
is used to determine how many random bits can be inserted into the base
address used for mmap allocations. Since 48-bit allocations are legal
with ARM64_VA_BITS=52, we need to make sure that the base address is
small enough to facilitate this.
Fixes: b6d00d47e81a ("arm64: mm: Introduce 52-bit Kernel VAs")
Signed-off-by: Kornel Dulęba <korneld@google.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20250417114754.3238273-1-korneld@google.com
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | arch/arm64/Kconfig | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index a182295e6f08..6527d0d5656a 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -333,9 +333,9 @@ config ARCH_MMAP_RND_BITS_MAX default 24 if ARM64_VA_BITS=39 default 27 if ARM64_VA_BITS=42 default 30 if ARM64_VA_BITS=47 - default 29 if ARM64_VA_BITS=48 && ARM64_64K_PAGES - default 31 if ARM64_VA_BITS=48 && ARM64_16K_PAGES - default 33 if ARM64_VA_BITS=48 + default 29 if (ARM64_VA_BITS=48 || ARM64_VA_BITS=52) && ARM64_64K_PAGES + default 31 if (ARM64_VA_BITS=48 || ARM64_VA_BITS=52) && ARM64_16K_PAGES + default 33 if (ARM64_VA_BITS=48 || ARM64_VA_BITS=52) default 14 if ARM64_64K_PAGES default 16 if ARM64_16K_PAGES default 18 |