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Subject[RFC PATCH v1 37/41] powerpc/32s: Move KUEP locking/unlocking in C
Date
This can be done in C, do it.

Unrolling the loop gains approx. 15% performance.

From now on, prepare_transfer_to_handler() is only for
interrupts from kernel.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/include/asm/book3s/32/kup.h | 31 -------------------
arch/powerpc/include/asm/interrupt.h | 3 ++
arch/powerpc/include/asm/kup.h | 8 +++++
arch/powerpc/kernel/entry_32.S | 17 ++---------
arch/powerpc/kernel/interrupt.c | 4 +++
arch/powerpc/mm/book3s32/Makefile | 1 +
arch/powerpc/mm/book3s32/kuep.c | 38 ++++++++++++++++++++++++
7 files changed, 56 insertions(+), 46 deletions(-)
create mode 100644 arch/powerpc/mm/book3s32/kuep.c

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 73bc5d2c431d..b97ea60f6fa3 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -7,37 +7,6 @@

#ifdef __ASSEMBLY__

-.macro kuep_update_sr gpr1, gpr2 /* NEVER use r0 as gpr2 due to addis */
-101: mtsrin \gpr1, \gpr2
- addi \gpr1, \gpr1, 0x111 /* next VSID */
- rlwinm \gpr1, \gpr1, 0, 0xf0ffffff /* clear VSID overflow */
- addis \gpr2, \gpr2, 0x1000 /* address of next segment */
- bdnz 101b
- isync
-.endm
-
-.macro kuep_lock gpr1, gpr2
-#ifdef CONFIG_PPC_KUEP
- li \gpr1, NUM_USER_SEGMENTS
- li \gpr2, 0
- mtctr \gpr1
- mfsrin \gpr1, \gpr2
- oris \gpr1, \gpr1, SR_NX@h /* set Nx */
- kuep_update_sr \gpr1, \gpr2
-#endif
-.endm
-
-.macro kuep_unlock gpr1, gpr2
-#ifdef CONFIG_PPC_KUEP
- li \gpr1, NUM_USER_SEGMENTS
- li \gpr2, 0
- mtctr \gpr1
- mfsrin \gpr1, \gpr2
- rlwinm \gpr1, \gpr1, 0, ~SR_NX /* Clear Nx */
- kuep_update_sr \gpr1, \gpr2
-#endif
-.endm
-
#ifdef CONFIG_PPC_KUAP

.macro kuap_update_sr gpr1, gpr2, gpr3 /* NEVER use r0 as gpr2 due to addis */
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index 550ad1d69a7b..e5e04e962165 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -21,6 +21,7 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
trace_hardirqs_off();

if (user_mode(regs)) {
+ kuep_lock();
current->thread.regs = regs;
account_cpu_user_entry();
}
@@ -83,6 +84,8 @@ static inline void interrupt_exit_prepare(struct pt_regs *regs, struct interrupt
exception_exit(state->ctx_state);
#endif

+ if (user_mode(regs))
+ kuep_unlock();
/*
* Book3S exits to user via interrupt_exit_user_prepare(), which does
* context tracking, which is a cleaner way to handle PREEMPT=y
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 7ec21af49a45..25671f711ec2 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -55,6 +55,14 @@ void setup_kuep(bool disabled);
static inline void setup_kuep(bool disabled) { }
#endif /* CONFIG_PPC_KUEP */

+#if defined(CONFIG_PPC_KUEP) && defined(CONFIG_PPC_BOOK3S_32)
+void kuep_lock(void);
+void kuep_unlock(void);
+#else
+static inline void kuep_lock(void) { }
+static inline void kuep_unlock(void) { }
+#endif
+
#ifdef CONFIG_PPC_KUAP
void setup_kuap(bool disabled);
#else
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 544a9a2270ff..3ae790a362d1 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -60,13 +60,9 @@
prepare_transfer_to_handler:
andi. r0,r9,MSR_PR
addi r12, r2, THREAD
- beq 2f
-#ifdef CONFIG_PPC_BOOK3S_32
- kuep_lock r11, r12
-#endif
- blr
+ bnelr

-2: /* if from kernel, check interrupted DOZE/NAP mode and
+ /* if from kernel, check interrupted DOZE/NAP mode and
* check for stack overflow
*/
kuap_save_and_lock r11, r12, r9, r5, r6
@@ -93,9 +89,6 @@ _ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont)
.globl transfer_to_syscall
transfer_to_syscall:
SAVE_NVGPRS(r1)
-#ifdef CONFIG_PPC_BOOK3S_32
- kuep_lock r11, r12
-#endif

/* Calling convention has r9 = orig r0, r10 = regs */
addi r10,r1,STACK_FRAME_OVERHEAD
@@ -112,9 +105,6 @@ ret_from_syscall:
cmplwi cr0,r5,0
bne- 2f
#endif /* CONFIG_PPC_47x */
-#ifdef CONFIG_PPC_BOOK3S_32
- kuep_unlock r5, r7
-#endif
kuap_check r2, r4
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
@@ -295,9 +285,6 @@ interrupt_return:
bne- .Lrestore_nvgprs

.Lfast_user_interrupt_return:
-#ifdef CONFIG_PPC_BOOK3S_32
- kuep_unlock r10, r11
-#endif
kuap_check r2, r4
lwz r11,_NIP(r1)
lwz r12,_MSR(r1)
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 6111acf61373..3c2e9b28b05d 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -30,6 +30,8 @@ notrace long system_call_exception(long r3, long r4, long r5,
syscall_fn f;
unsigned long expected_msr;

+ kuep_lock();
+
regs->orig_gpr3 = r3;

if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
@@ -355,6 +357,8 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
*/
kuap_user_restore(regs);
#endif
+ kuep_unlock();
+
return ret;
}

diff --git a/arch/powerpc/mm/book3s32/Makefile b/arch/powerpc/mm/book3s32/Makefile
index 446d9de88ce4..7f0c8a78ba0c 100644
--- a/arch/powerpc/mm/book3s32/Makefile
+++ b/arch/powerpc/mm/book3s32/Makefile
@@ -9,3 +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
diff --git a/arch/powerpc/mm/book3s32/kuep.c b/arch/powerpc/mm/book3s32/kuep.c
new file mode 100644
index 000000000000..7b3e4c57aaf9
--- /dev/null
+++ b/arch/powerpc/mm/book3s32/kuep.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <asm/reg.h>
+#include <asm/task_size_32.h>
+#include <asm/mmu.h>
+
+#define KUEP_UPDATE_TWO_USER_SEGMENTS(n) do { \
+ if (TASK_SIZE > (n << 28)) \
+ mtsr(val1, n << 28); \
+ if (TASK_SIZE > ((n + 1) << 28)) \
+ mtsr(val2, (n + 1) << 28); \
+ val1 = (val1 + 0x222) & 0xf0ffffff; \
+ val2 = (val2 + 0x222) & 0xf0ffffff; \
+} while (0)
+
+static __always_inline void kuep_update(u32 val)
+{
+ int val1 = val;
+ int val2 = (val + 0x111) & 0xf0ffffff;
+
+ KUEP_UPDATE_TWO_USER_SEGMENTS(0);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(2);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(4);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(6);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(8);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(10);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(12);
+ KUEP_UPDATE_TWO_USER_SEGMENTS(14);
+}
+
+void kuep_lock(void)
+{
+ kuep_update(mfsr(0) | SR_NX);
+}
+
+void kuep_unlock(void)
+{
+ kuep_update(mfsr(0) & ~SR_NX);
+}
--
2.25.0
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