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riscv: Improve arch_get_mmap_end() macro

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This macro caused me some confusion, which took some reviewer's time to
make it clear, so I propose adding a short comment in code to avoid
confusion in the future.

Also, added some improvements to the macro, such as removing the
assumption of VA_USER_SV57 being the largest address space.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20240103160024.70305-3-leobras@redhat.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Leonardo Bras 2024-01-03 13:00:19 -03:00 committed by Palmer Dabbelt
parent b85ea95d08
commit 6be7ee4beb
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1 changed files with 9 additions and 3 deletions
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12
arch/riscv/include/asm/processor.h
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@ -18,15 +18,21 @@
#define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
#define STACK_TOP_MAX TASK_SIZE_64
/*
* addr is a hint to the maximum userspace address that mmap should provide, so
* this macro needs to return the largest address space available so that
* mmap_end < addr, being mmap_end the top of that address space.
* See Documentation/arch/riscv/vm-layout.rst for more details.
*/
#define arch_get_mmap_end(addr, len, flags) \
({ \
unsigned long mmap_end; \
typeof(addr) _addr = (addr); \
if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \
mmap_end = STACK_TOP_MAX; \
else if ((_addr) >= VA_USER_SV57) \
mmap_end = STACK_TOP_MAX; \
else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
mmap_end = VA_USER_SV57; \
else if (((_addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) \
mmap_end = VA_USER_SV48; \
else \
mmap_end = VA_USER_SV39; \