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Message-ID: <20240103160024.70305-3-leobras@redhat.com>
Date: Wed, 3 Jan 2024 13:00:19 -0300
From: Leonardo Bras <leobras@...hat.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Eric Biederman <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Oleg Nesterov <oleg@...hat.com>,
Leonardo Bras <leobras@...hat.com>,
Guo Ren <guoren@...nel.org>,
Andy Chiu <andy.chiu@...ive.com>,
Conor Dooley <conor.dooley@...rochip.com>,
Xiao Wang <xiao.w.wang@...el.com>,
Vincent Chen <vincent.chen@...ive.com>,
Charlie Jenkins <charlie@...osinc.com>,
Greg Ungerer <gerg@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Kemeng Shi <shikemeng@...weicloud.com>,
Alexandre Ghiti <alexghiti@...osinc.com>,
David Hildenbrand <david@...hat.com>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Qinglin Pan <panqinglin2020@...as.ac.cn>,
Greentime Hu <greentime.hu@...ive.com>,
Baoquan He <bhe@...hat.com>,
Clément Léger <cleger@...osinc.com>
Cc: linux-riscv@...ts.infradead.org,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: [PATCH v1 1/5] 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@...hat.com>
Reviewed-by: Guo Ren <guoren@...nel.org>
---
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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