2019-08-20 14:54:49

by He Zhe

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

From: He Zhe <[email protected]>

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 <[email protected]>
---
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

2019-08-21 09:54:50

by Jessica Yu

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

+++ [email protected] [20/08/19 22:53 +0800]:
>From: He Zhe <[email protected]>
>
>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 <[email protected]>
>---
>This patch is based on the top of modules-next tree, 38f054d549a8.

I've applied this. Thanks!

Jessica

> 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
>