Re: [PATCH v3 37/41] powerpc/32s: Move KUEP locking/unlocking in C

[Christophe Leroy]

Le 12/03/2021 à 13:50, Christophe Leroy a écrit :

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.le...@csgroup.eu>
---
  arch/powerpc/include/asm/book3s/32/kup.h | 31 -------------------
  arch/powerpc/include/asm/interrupt.h     |  6 +++-
  arch/powerpc/include/asm/kup.h           |  8 +++++
  arch/powerpc/kernel/entry_32.S           | 16 ----------
  arch/powerpc/kernel/head_32.h            |  3 ++
  arch/powerpc/kernel/head_booke.h         |  3 ++
  arch/powerpc/kernel/interrupt.c          |  4 +++
  arch/powerpc/mm/book3s32/Makefile        |  1 +
  arch/powerpc/mm/book3s32/kuep.c          | 38 ++++++++++++++++++++++++
  9 files changed, 62 insertions(+), 48 deletions(-)
  create mode 100644 arch/powerpc/mm/book3s32/kuep.c

diff --git a/arch/powerpc/mm/book3s32/kuep.c b/arch/powerpc/mm/book3s32/kuep.c
new file mode 100644
index 000000000000..c70532568a28
--- /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>

Need to add <asm/kup.h> to make Robot happy (missing prototypes of kuep_lock() 
and kuep_unlock())

+
+#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);
+}