linux-kernel - [PATCH v3 1/4] powerpc: Remove probe_user_read

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Date:   Wed, 14 Apr 2021 13:08:40 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, jniethe5@...il.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 1/4] powerpc: Remove probe_user_read_inst()

Its name comes from former probe_user_read() function.
That function is now called copy_from_user_nofault().

probe_user_read_inst() uses copy_from_user_nofault() to read only
a few bytes. It is suboptimal.

It does the same as get_user_inst() but in addition disables
page faults.

But on the other hand, it is not used for the time being. So remove it
for now. If one day it is really needed, we can give it a new name
more in line with today's naming, and implement it using get_user_inst()

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/inst.h |  3 ---
 arch/powerpc/lib/inst.c         | 31 -------------------------------
 2 files changed, 34 deletions(-)

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index 19e18af2fac9..2902d4e6a363 100644
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -175,9 +175,6 @@ static inline char *__ppc_inst_as_str(char str[PPC_INST_STR_LEN], struct ppc_ins
 	__str;				\
 })
 
-int probe_user_read_inst(struct ppc_inst *inst,
-			 struct ppc_inst __user *nip);
-
 int probe_kernel_read_inst(struct ppc_inst *inst,
 			   struct ppc_inst *src);
 
diff --git a/arch/powerpc/lib/inst.c b/arch/powerpc/lib/inst.c
index 9cc17eb62462..c57b3548de37 100644
--- a/arch/powerpc/lib/inst.c
+++ b/arch/powerpc/lib/inst.c
@@ -9,24 +9,6 @@
 #include <asm/ppc-opcode.h>
 
 #ifdef CONFIG_PPC64
-int probe_user_read_inst(struct ppc_inst *inst,
-			 struct ppc_inst __user *nip)
-{
-	unsigned int val, suffix;
-	int err;
-
-	err = copy_from_user_nofault(&val, nip, sizeof(val));
-	if (err)
-		return err;
-	if (get_op(val) == OP_PREFIX) {
-		err = copy_from_user_nofault(&suffix, (void __user *)nip + 4, 4);
-		*inst = ppc_inst_prefix(val, suffix);
-	} else {
-		*inst = ppc_inst(val);
-	}
-	return err;
-}
-
 int probe_kernel_read_inst(struct ppc_inst *inst,
 			   struct ppc_inst *src)
 {
@@ -45,19 +27,6 @@ int probe_kernel_read_inst(struct ppc_inst *inst,
 	return err;
 }
 #else /* !CONFIG_PPC64 */
-int probe_user_read_inst(struct ppc_inst *inst,
-			 struct ppc_inst __user *nip)
-{
-	unsigned int val;
-	int err;
-
-	err = copy_from_user_nofault(&val, nip, sizeof(val));
-	if (!err)
-		*inst = ppc_inst(val);
-
-	return err;
-}
-
 int probe_kernel_read_inst(struct ppc_inst *inst,
 			   struct ppc_inst *src)
 {
-- 
2.25.0