The patch titled
Subject: livepatching: handle ancient compilers with more grace
has been added to the -mm tree. Its filename is
livepatching-handle-ancient-compilers-with-more-grace.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/livepatching-handle-ancient-compilers-with-more-grace.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/livepatching-handle-ancient-compilers-with-more-grace.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Jiri Kosina <jkosina@xxxxxxx>
Subject: livepatching: handle ancient compilers with more grace
We are aborting a build in case when gcc doesn't support fentry on x86_64
(regs->ip modification can't really reliably work with mcount).
This however breaks allmodconfig for people with older gccs that don't
support -mfentry.
Turn the build-time failure into runtime failure, resulting in the whole
infrastructure not being initialized if CC_USING_FENTRY is unset.
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/livepatch.h | 6 +++++-
kernel/livepatch/core.c | 6 ++++++
2 files changed, 11 insertions(+), 1 deletion(-)
diff -puN arch/x86/include/asm/livepatch.h~livepatching-handle-ancient-compilers-with-more-grace arch/x86/include/asm/livepatch.h
--- a/arch/x86/include/asm/livepatch.h~livepatching-handle-ancient-compilers-with-more-grace
+++ a/arch/x86/include/asm/livepatch.h
@@ -25,9 +25,13 @@
#include <linux/ftrace.h>
#ifdef CONFIG_LIVE_PATCHING
+static inline int klp_check_compiler_support(void)
+{
#ifndef CC_USING_FENTRY
-#error Your compiler must support -mfentry for live patching to work
+ return 1;
#endif
+ return 0;
+}
extern int klp_write_module_reloc(struct module *mod, unsigned long type,
unsigned long loc, unsigned long value);
diff -puN kernel/livepatch/core.c~livepatching-handle-ancient-compilers-with-more-grace kernel/livepatch/core.c
--- a/kernel/livepatch/core.c~livepatching-handle-ancient-compilers-with-more-grace
+++ a/kernel/livepatch/core.c
@@ -911,6 +911,12 @@ static int klp_init(void)
{
int ret;
+ ret = klp_check_compiler_support();
+ if (ret) {
+ pr_info("Your compiler is too old; turning off.\n");
+ return -EINVAL;
+ }
+
ret = register_module_notifier(&klp_module_nb);
if (ret)
return ret;
_
Patches currently in -mm which might be from jkosina@xxxxxxx are
linux-next.patch
livepatching-handle-ancient-compilers-with-more-grace.patch
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