linux-kernel - [PATCH v3] kprobes: remove duplicated strong free_insn

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Date:   Tue, 8 Jun 2021 18:57:36 +1200
From:   Barry Song <song.bao.hua@...ilicon.com>
To:     <akpm@...ux-foundation.org>, <hpa@...or.com>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <bp@...en8.de>, <hca@...ux.ibm.com>,
        <gor@...ux.ibm.com>, <borntraeger@...ibm.com>,
        <naveen.n.rao@...ux.ibm.com>, <anil.s.keshavamurthy@...el.com>,
        <davem@...emloft.net>, <mhiramat@...nel.org>,
        <linux-s390@...r.kernel.org>, <x86@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <liuqi115@...wei.com>,
        <linuxarm@...wei.com>, Barry Song <song.bao.hua@...ilicon.com>,
        "Christoph Hellwig" <hch@...radead.org>
Subject: [PATCH v3] kprobes: remove duplicated strong free_insn_page in x86 and s390

free_insn_page() in x86 and s390 is same with the common weak function
in kernel/kprobes.c.
Plus,  the comment "Recover page to RW mode before releasing it" in x86
seems insensible to be there since resetting mapping is done by common
code in vfree() of module_memfree().
So drop these two duplicated strong functions and related comment, then
mark the common one in kernel/kprobes.c strong.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>
Acked-by: Heiko Carstens <hca@...ux.ibm.com>
Cc: Christoph Hellwig <hch@...radead.org>
Signed-off-by: Barry Song <song.bao.hua@...ilicon.com>
---
 -v3: mark free_insn_page as static according to Christoph's comment

 arch/s390/kernel/kprobes.c     | 5 -----
 arch/x86/kernel/kprobes/core.c | 6 ------
 include/linux/kprobes.h        | 1 -
 kernel/kprobes.c               | 2 +-
 4 files changed, 1 insertion(+), 13 deletions(-)

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index aae24dc75df6..60cfbd24229b 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -44,11 +44,6 @@ void *alloc_insn_page(void)
 	return page;
 }
 
-void free_insn_page(void *page)
-{
-	module_memfree(page);
-}
-
 static void *alloc_s390_insn_page(void)
 {
 	if (xchg(&insn_page_in_use, 1) == 1)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index d3d65545cb8b..3bce67d3a03c 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -422,12 +422,6 @@ void *alloc_insn_page(void)
 	return page;
 }
 
-/* Recover page to RW mode before releasing it */
-void free_insn_page(void *page)
-{
-	module_memfree(page);
-}
-
 /* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */
 
 static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 1883a4a9f16a..c98a35a75f40 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -407,7 +407,6 @@ int enable_kprobe(struct kprobe *kp);
 void dump_kprobe(struct kprobe *kp);
 
 void *alloc_insn_page(void);
-void free_insn_page(void *page);
 
 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 		       char *sym);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 745f08fdd7a6..e0c4c9d57299 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -106,7 +106,7 @@ void __weak *alloc_insn_page(void)
 	return module_alloc(PAGE_SIZE);
 }
 
-void __weak free_insn_page(void *page)
+static void free_insn_page(void *page)
 {
 	module_memfree(page);
 }
-- 
2.25.1