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authorLeonardo Bras <leobras@redhat.com>2024-01-03 13:00:19 -0300
committerPalmer Dabbelt <palmer@rivosinc.com>2024-03-19 16:39:36 -0700
commit6be7ee4bebd14b8e7e040a5e7fd6aec3d9167c72 (patch)
tree0d10e98b0b0e0ba00342229f266cdd5bc37111d7 /arch
parentb85ea95d086471afb4ad062012a4d73cd328fa86 (diff)
riscv: Improve arch_get_mmap_end() macro
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/riscv/include/asm/processor.h12
1 files changed, 9 insertions, 3 deletions
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index f19f861cda54..2278e2a8362a 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -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; \