linux-kernel - [PATCH] modules: page-align module section allocations only for arches supporting strict module rwx

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Date:   Tue, 20 Aug 2019 22:53:10 +0800
From:   <zhe.he@...driver.com>
To:     <jeyu@...nel.org>, <linux-kernel@...r.kernel.org>,
        <zhe.he@...driver.com>
Subject: [PATCH] modules: page-align module section allocations only for arches supporting strict module rwx

From: He Zhe <zhe.he@...driver.com>

We should keep the case of "#define debug_align(X) (X)" for all arches
without CONFIG_HAS_STRICT_MODULE_RWX ability, which would save people, who
are sensitive to system size, a lot of memory when using modules,
especially for embedded systems. This is also the intention of the
original #ifdef... statement and still valid for now.

Note that this still keeps the effect of the fix of the following commit,
38f054d549a8 ("modules: always page-align module section allocations"),
since when CONFIG_ARCH_HAS_STRICT_MODULE_RWX is enabled, module pages are
aligned.

Signed-off-by: He Zhe <zhe.he@...driver.com>
---
This patch is based on the top of modules-next tree, 38f054d549a8.

 kernel/module.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c
index cd8df51..9ee9342 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -64,9 +64,14 @@

 /*
  * Modules' sections will be aligned on page boundaries
- * to ensure complete separation of code and data
+ * to ensure complete separation of code and data, but
+ * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y
  */
+#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
 # define debug_align(X) ALIGN(X, PAGE_SIZE)
+#else
+# define debug_align(X) (X)
+#endif

 /* If this is set, the section belongs in the init part of the module */
 #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
-- 
2.7.4