diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index 7d1a3d1543fc..9af93d05e6fa 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -284,5 +284,48 @@ static inline unsigned long radix__get_tree_size(void)
int radix__create_section_mapping(unsigned long start, unsigned long end, int nid);
int radix__remove_section_mapping(unsigned long start, unsigned long end);
#endif /* CONFIG_MEMORY_HOTPLUG */
+
+#ifdef CONFIG_PPC_KUAP
+#include <asm/reg.h>
+/*
+ * We do have the ability to individually lock/unlock reads and writes rather
+ * than both at once, however it's a significant performance hit due to needing
+ * to do a read-modify-write, which adds a mfspr, which is slow. As a result,
+ * locking/unlocking both at once is preferred.
+ */
+static inline void __unlock_user_rd_access(void)
+{
+ if (!mmu_has_feature(MMU_FTR_RADIX_KUAP))
+ return;
+
+ mtspr(SPRN_AMR, 0);
+ isync();
+}
+
+static inline void __lock_user_rd_access(void)
+{
+ if (!mmu_has_feature(MMU_FTR_RADIX_KUAP))
+ return;
+
+ mtspr(SPRN_AMR, AMR_LOCKED);
+}
+
+static inline void __unlock_user_wr_access(void)
+{
+ if (!mmu_has_feature(MMU_FTR_RADIX_KUAP))
+ return;
+
+ mtspr(SPRN_AMR, 0);
+ isync();
+}
+
+static inline void __lock_user_wr_access(void)
+{
+ if (!mmu_has_feature(MMU_FTR_RADIX_KUAP))
+ return;
+
+ mtspr(SPRN_AMR, AMR_LOCKED);
+}
+#endif /* CONFIG_PPC_KUAP */
#endif /* __ASSEMBLY__ */
#endifdiff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h
index 555e22d5e07f..bf25015834ee 100644
--- a/arch/powerpc/include/asm/exception-64e.h
+++ b/arch/powerpc/include/asm/exception-64e.h
@@ -215,5 +215,8 @@ exc_##label##_book3e:
#define RFI_TO_USER \
rfi
+#define UNLOCK_USER_ACCESS(reg)
+#define LOCK_USER_ACCESS(reg)
+
#endif /* _ASM_POWERPC_EXCEPTION_64E_H */
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 3b4767ed3ec5..d92614c66d87 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -264,6 +264,19 @@ BEGIN_FTR_SECTION_NESTED(943) \
std ra,offset(r13); \
END_FTR_SECTION_NESTED(ftr,ftr,943)
+#define LOCK_USER_ACCESS(reg) \
+BEGIN_MMU_FTR_SECTION_NESTED(944) \
+ LOAD_REG_IMMEDIATE(reg,AMR_LOCKED); \
+ mtspr SPRN_AMR,reg; \
+END_MMU_FTR_SECTION_NESTED(MMU_FTR_RADIX_KUAP,MMU_FTR_RADIX_KUAP,944)
+
+#define UNLOCK_USER_ACCESS(reg) \
+BEGIN_MMU_FTR_SECTION_NESTED(945) \
+ li reg,0; \
+ mtspr SPRN_AMR,reg; \
+ isync; \
+END_MMU_FTR_SECTION_NESTED(MMU_FTR_RADIX_KUAP,MMU_FTR_RADIX_KUAP,945)
+
#define EXCEPTION_PROLOG_0(area) \
GET_PACA(r13); \
std r9,area+EX_R9(r13); /* save r9 */ \
@@ -500,7 +513,11 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
beq 4f; /* if from kernel mode */ \
ACCOUNT_CPU_USER_ENTRY(r13, r9, r10); \
SAVE_PPR(area, r9); \
-4: EXCEPTION_PROLOG_COMMON_2(area) \
+4: lbz r9,PACA_USER_ACCESS_ALLOWED(r13); \
+ cmpwi cr1,r9,0; \
+ beq 5f; \
+ LOCK_USER_ACCESS(r9); \
+5: EXCEPTION_PROLOG_COMMON_2(area) \
EXCEPTION_PROLOG_COMMON_3(n) \
ACCOUNT_STOLEN_TIME
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 5631a906af55..a1450d56d0db 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -107,6 +107,10 @@
*/
#define MMU_FTR_1T_SEGMENT ASM_CONST(0x40000000)
+/* Supports KUAP (key 0 controlling userspace addresses) on radix
+ */
+#define MMU_FTR_RADIX_KUAP ASM_CONST(0x80000000)
+
/* MMU feature bit sets for various CPUs */
#define MMU_FTRS_DEFAULT_HPTE_ARCH_V2 \
MMU_FTR_HPTE_TABLE | MMU_FTR_PPCAS_ARCH_V2
@@ -143,7 +147,10 @@ enum {
MMU_FTR_KERNEL_RO | MMU_FTR_68_BIT_VA |
#ifdef CONFIG_PPC_RADIX_MMU
MMU_FTR_TYPE_RADIX |
-#endif
+#ifdef CONFIG_PPC_KUAP
+ MMU_FTR_RADIX_KUAP |
+#endif /* CONFIG_PPC_KUAP */
+#endif /* CONFIG_PPC_RADIX_MMU */
0,
};
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index de52c3166ba4..d9598e6790d8 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -246,6 +246,7 @@
#define SPRN_DSCR 0x11
#define SPRN_CFAR 0x1c /* Come From Address Register */
#define SPRN_AMR 0x1d /* Authority Mask Register */
+#define AMR_LOCKED 0xC000000000000000UL /* Read & Write disabled */
#define SPRN_UAMOR 0x9d /* User Authority Mask Override Register */
#define SPRN_AMOR 0x15d /* Authority Mask Override Register */
#define SPRN_ACOP 0x1F /* Available Coprocessor Register */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 7b1693adff2a..d5879f32bd34 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -297,7 +297,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
b . /* prevent speculative execution */
/* exit to kernel */
-1: ld r2,GPR2(r1)
+1: /* if the AMR was unlocked before, unlock it again */
+ lbz r2,PACA_USER_ACCESS_ALLOWED(r13)
+ cmpwi cr1,0
+ bne 2f
+ UNLOCK_USER_ACCESS(r2)
+2: ld r2,GPR2(r1)
ld r1,GPR1(r1)
mtlr r4
mtcr r5
@@ -983,7 +988,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
RFI_TO_USER
b . /* prevent speculative execution */
-1: mtspr SPRN_SRR1,r3
+1: /* exit to kernel */
+ /* if the AMR was unlocked before, unlock it again */
+ lbz r2,PACA_USER_ACCESS_ALLOWED(r13)
+ cmpwi cr1,0
+ bne 2f
+ UNLOCK_USER_ACCESS(r2)
+
+2: mtspr SPRN_SRR1,r3
ld r2,_CCR(r1)
mtcrf 0xFF,r2
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
index f08a459b4255..b064b542e09f 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -29,6 +29,7 @@
#include <asm/powernv.h>
#include <asm/sections.h>
#include <asm/trace.h>
+#include <asm/uaccess.h>
#include <trace/events/thp.h>
@@ -550,6 +551,17 @@ void setup_kuep(bool disabled)
mtspr(SPRN_IAMR, (1ul << 62));
}
+void setup_kuap(bool disabled)
+{
+ if (disabled)
+ return;
+
+ pr_warn("Activating Kernel Userspace Access Prevention\n");
+
+ cur_cpu_spec->mmu_features |= MMU_FTR_RADIX_KUAP;
+ mtspr(SPRN_AMR, AMR_LOCKED);
+}
+
void __init radix__early_init_mmu(void)
{
unsigned long lpcr;diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index b271b283c785..bb3cf915016f 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -7,6 +7,7 @@
#include <asm/mman.h>
#include <asm/setup.h>
+#include <asm/uaccess.h>
#include <linux/pkeys.h>
#include <linux/of_device.h>
@@ -266,7 +267,8 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
void thread_pkey_regs_save(struct thread_struct *thread)
{
- if (static_branch_likely(&pkey_disabled))
+ if (static_branch_likely(&pkey_disabled) &&
+ !mmu_has_feature(MMU_FTR_RADIX_KUAP))
return;
/*@@ -280,7 +282,8 @@ void thread_pkey_regs_save(struct thread_struct *thread)
void thread_pkey_regs_restore(struct thread_struct *new_thread,
struct thread_struct *old_thread)
{
- if (static_branch_likely(&pkey_disabled))
+ if (static_branch_likely(&pkey_disabled) &&
+ !mmu_has_feature(MMU_FTR_RADIX_KUAP))
return;
if (old_thread->amr != new_thread->amr)diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index e6831d0ec159..5fbfa041194d 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -335,6 +335,7 @@ config PPC_RADIX_MMU
depends on PPC_BOOK3S_64
select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
select PPC_HAVE_KUEP
+ select PPC_HAVE_KUAP
default y
help
Enable support for the Power ISA 3.0 Radix style MMU. Currently this
--
2.19.1