linux-kernel - [PATCH v3 08/22] powerpc/kuep: Remove 'nosmep' boot time parameter except for book3s/64

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Message-Id: <4c36df18b41c988c4512f45d96220486adbe4c99.1634627931.git.christophe.leroy@csgroup.eu>
Date:   Tue, 19 Oct 2021 09:29:19 +0200
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>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 08/22] powerpc/kuep: Remove 'nosmep' boot time parameter except for book3s/64

Deactivating KUEP at boot time is unrelevant for PPC32 and BOOK3E/64.

Remove it.

It allows to refactor setup_kuep() via a __weak function
that only PPC64s will overide for now.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 Documentation/admin-guide/kernel-parameters.txt |  2 +-
 arch/powerpc/include/asm/kup.h                  |  5 -----
 arch/powerpc/mm/book3s32/Makefile               |  1 -
 arch/powerpc/mm/book3s32/kuep.c                 | 13 -------------
 arch/powerpc/mm/init-common.c                   | 15 +++++++++++++++
 arch/powerpc/mm/nohash/44x.c                    | 10 ----------
 arch/powerpc/mm/nohash/8xx.c                    |  7 -------
 7 files changed, 16 insertions(+), 37 deletions(-)
 delete mode 100644 arch/powerpc/mm/book3s32/kuep.c

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 43dc35fe5bc0..fce1c13ce642 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3354,7 +3354,7 @@
 			Disable SMAP (Supervisor Mode Access Prevention)
 			even if it is supported by processor.
 
-	nosmep		[X86,PPC]
+	nosmep		[X86,PPC64s]
 			Disable SMEP (Supervisor Mode Execution Prevention)
 			even if it is supported by processor.
 
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 94734a8eb54d..fa8513b7acca 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -33,12 +33,7 @@ extern bool disable_kuap;
 #include <linux/pgtable.h>
 
 void setup_kup(void);
-
-#ifdef CONFIG_PPC_KUEP
 void setup_kuep(bool disabled);
-#else
-static inline void setup_kuep(bool disabled) { }
-#endif /* CONFIG_PPC_KUEP */
 
 #ifdef CONFIG_PPC_KUAP
 void setup_kuap(bool disabled);
diff --git a/arch/powerpc/mm/book3s32/Makefile b/arch/powerpc/mm/book3s32/Makefile
index 15f4773643d2..50dd8f6bdf46 100644
--- a/arch/powerpc/mm/book3s32/Makefile
+++ b/arch/powerpc/mm/book3s32/Makefile
@@ -9,5 +9,4 @@ endif
 obj-y += mmu.o mmu_context.o
 obj-$(CONFIG_PPC_BOOK3S_603) += nohash_low.o
 obj-$(CONFIG_PPC_BOOK3S_604) += hash_low.o tlb.o
-obj-$(CONFIG_PPC_KUEP) += kuep.o
 obj-$(CONFIG_PPC_KUAP) += kuap.o
diff --git a/arch/powerpc/mm/book3s32/kuep.c b/arch/powerpc/mm/book3s32/kuep.c
deleted file mode 100644
index 78fc48eee510..000000000000
--- a/arch/powerpc/mm/book3s32/kuep.c
+++ /dev/null
@@ -1,13 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#include <asm/code-patching.h>
-#include <asm/kup.h>
-#include <asm/smp.h>
-
-void setup_kuep(bool disabled)
-{
-	if (smp_processor_id() != boot_cpuid)
-		return;
-
-	pr_info("Activating Kernel Userspace Execution Prevention\n");
-}
diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
index b4f3437aee38..b22e0649e2d3 100644
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -20,6 +20,7 @@
 #include <linux/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/kup.h>
+#include <asm/smp.h>
 
 phys_addr_t memstart_addr __ro_after_init = (phys_addr_t)~0ull;
 EXPORT_SYMBOL_GPL(memstart_addr);
@@ -33,6 +34,9 @@ bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
 
 static int __init parse_nosmep(char *p)
 {
+	if (!IS_ENABLED(CONFIG_PPC_BOOKS_64))
+		return 0;
+
 	disable_kuep = true;
 	pr_warn("Disabling Kernel Userspace Execution Prevention\n");
 	return 0;
@@ -47,6 +51,17 @@ static int __init parse_nosmap(char *p)
 }
 early_param("nosmap", parse_nosmap);
 
+void __weak setup_kuep(bool disabled)
+{
+	if (!IS_ENABLED(CONFIG_PPC_KUEP) || disabled)
+		return;
+
+	if (smp_processor_id() != boot_cpuid)
+		return;
+
+	pr_info("Activating Kernel Userspace Execution Prevention\n");
+}
+
 void setup_kup(void)
 {
 	setup_kuap(disable_kuap);
diff --git a/arch/powerpc/mm/nohash/44x.c b/arch/powerpc/mm/nohash/44x.c
index ceb290df1fb5..796c824acc8c 100644
--- a/arch/powerpc/mm/nohash/44x.c
+++ b/arch/powerpc/mm/nohash/44x.c
@@ -240,13 +240,3 @@ void __init mmu_init_secondary(int cpu)
 	}
 }
 #endif /* CONFIG_SMP */
-
-#ifdef CONFIG_PPC_KUEP
-void setup_kuep(bool disabled)
-{
-	if (smp_processor_id() != boot_cpuid)
-		return;
-
-	pr_info("Activating Kernel Userspace Execution Prevention\n");
-}
-#endif
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index e878e8124ee6..36010d1c0bc4 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -212,13 +212,6 @@ void __init setup_initial_memory_limit(phys_addr_t first_memblock_base,
 	memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_32M));
 }
 
-#ifdef CONFIG_PPC_KUEP
-void setup_kuep(bool disabled)
-{
-	pr_info("Activating Kernel Userspace Execution Prevention\n");
-}
-#endif
-
 #ifdef CONFIG_PPC_KUAP
 struct static_key_false disable_kuap_key;
 EXPORT_SYMBOL(disable_kuap_key);
-- 
2.31.1