From: Leonardo Bras <leobras@redhat.com>
To: "Paul Walmsley" <paul.walmsley@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Björn Töpel" <bjorn@rivosinc.com>,
"Conor Dooley" <conor.dooley@microchip.com>,
"Vincent Chen" <vincent.chen@sifive.com>,
"Andy Chiu" <andy.chiu@sifive.com>,
"Leonardo Bras" <leobras@redhat.com>,
"Charlie Jenkins" <charlie@rivosinc.com>,
"Clément Léger" <cleger@rivosinc.com>,
"Guo Ren" <guoren@kernel.org>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro
Date: Fri, 22 Dec 2023 05:27:10 -0300 [thread overview]
Message-ID: <20231222082711.454374-1-leobras@redhat.com> (raw)
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>
---
arch/riscv/include/asm/processor.h | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index f19f861cda549..2278e2a8362af 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; \
--
2.43.0
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next reply other threads:[~2023-12-22 8:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-22 8:27 Leonardo Bras [this message]
2023-12-22 11:48 ` [RFC PATCH 1/1] riscv: Improve arch_get_mmap_end() macro Guo Ren
2023-12-22 17:15 ` Leonardo Bras
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