powerpc/kuap: Avoid useless jump_label on empty function

Disassembly of interrupt_enter_prepare() shows a pointless nop
before the mftb

  c000abf0 <interrupt_enter_prepare>:
  c000abf0:       81 23 00 84     lwz     r9,132(r3)
  c000abf4:       71 29 40 00     andi.   r9,r9,16384
  c000abf8:       41 82 00 28     beq-    c000ac20 <interrupt_enter_prepare+0x30>
  c000abfc: ===>  60 00 00 00     nop	<====
  c000ac00:       7d 0c 42 e6     mftb    r8
  c000ac04:       80 e2 00 08     lwz     r7,8(r2)
  c000ac08:       81 22 00 28     lwz     r9,40(r2)
  c000ac0c:       91 02 00 24     stw     r8,36(r2)
  c000ac10:       7d 29 38 50     subf    r9,r9,r7
  c000ac14:       7d 29 42 14     add     r9,r9,r8
  c000ac18:       91 22 00 08     stw     r9,8(r2)
  c000ac1c:       4e 80 00 20     blr
  c000ac20:       60 00 00 00     nop
  c000ac24:       7d 5a c2 a6     mfmd_ap r10
  c000ac28:       3d 20 de 00     lis     r9,-8704
  c000ac2c:       91 43 00 b0     stw     r10,176(r3)
  c000ac30:       7d 3a c3 a6     mtspr   794,r9
  c000ac34:       4e 80 00 20     blr

That comes from the call to kuap_loc(), allthough __kuap_lock() is an
empty function on the 8xx.

To avoid that, only perform kuap_is_disabled() check when there is
something to do with __kuap_lock().

Do the same with __kuap_save_and_lock() and
__kuap_get_and_assert_locked().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/a854d25bea375d4ba6ca9c2617f9edbba397100a.1689091022.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 678f9c9d89b6ab75fab7abc68b87d764d83eb4d1..466a19cfb4dfd55cd6244910b299ecf27a82d3cf 100644 (file)
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -77,10 +77,6 @@ static inline void kuap_unlock(unsigned long addr, bool ool)
                kuap_unlock_all_ool();
 }
 
-static inline void __kuap_lock(void)
-{
-}
-
 static inline void __kuap_save_and_lock(struct pt_regs *regs)
 {
        unsigned long kuap = current->thread.kuap;
@@ -92,6 +88,7 @@ static inline void __kuap_save_and_lock(struct pt_regs *regs)
        current->thread.kuap = KUAP_NONE;
        kuap_lock_addr(kuap, false);
 }
+#define __kuap_save_and_lock __kuap_save_and_lock
 
 static inline void kuap_user_restore(struct pt_regs *regs)
 {
@@ -120,6 +117,7 @@ static inline unsigned long __kuap_get_and_assert_locked(void)
 
        return kuap;
 }
+#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
 
 static __always_inline void __allow_user_access(void __user *to, const void __user *from,
                                                u32 size, unsigned long dir)

diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 84c09e546115a7da6c3a4521d16c4ca2003c057a..2a7bd3ecc5565666fbe17e3a489477e38564ab54 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -298,15 +298,9 @@ static inline unsigned long __kuap_get_and_assert_locked(void)
                WARN_ON_ONCE(amr != AMR_KUAP_BLOCKED);
        return amr;
 }
+#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
 
-/* Do nothing, book3s/64 does that in ASM */
-static inline void __kuap_lock(void)
-{
-}
-
-static inline void __kuap_save_and_lock(struct pt_regs *regs)
-{
-}
+/* __kuap_lock() not required, book3s/64 does that in ASM */
 
 /*
  * We support individually allowing read or write, but we don't support nesting

diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index d751ddd081108176c9793c5e7b92eee0f252fda0..24cde16c4fbede6e623d7c40e83eadb276dd1847 100644 (file)
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -52,16 +52,9 @@ __bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
        return false;
 }
 
-static inline void __kuap_lock(void) { }
-static inline void __kuap_save_and_lock(struct pt_regs *regs) { }
 static inline void kuap_user_restore(struct pt_regs *regs) { }
 static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr) { }
 
-static inline unsigned long __kuap_get_and_assert_locked(void)
-{
-       return 0;
-}
-
 /*
  * book3s/64/kup-radix.h defines these functions for the !KUAP case to flush
  * the L1D cache after user accesses. Only include the empty stubs for other
@@ -85,29 +78,24 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
        return __bad_kuap_fault(regs, address, is_write);
 }
 
-static __always_inline void kuap_assert_locked(void)
-{
-       if (kuap_is_disabled())
-               return;
-
-       if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
-               __kuap_get_and_assert_locked();
-}
-
 static __always_inline void kuap_lock(void)
 {
+#ifdef __kuap_lock
        if (kuap_is_disabled())
                return;
 
        __kuap_lock();
+#endif
 }
 
 static __always_inline void kuap_save_and_lock(struct pt_regs *regs)
 {
+#ifdef __kuap_save_and_lock
        if (kuap_is_disabled())
                return;
 
        __kuap_save_and_lock(regs);
+#endif
 }
 
 static __always_inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)
@@ -120,10 +108,17 @@ static __always_inline void kuap_kernel_restore(struct pt_regs *regs, unsigned l
 
 static __always_inline unsigned long kuap_get_and_assert_locked(void)
 {
-       if (kuap_is_disabled())
-               return 0;
+#ifdef __kuap_get_and_assert_locked
+       if (!kuap_is_disabled())
+               return __kuap_get_and_assert_locked();
+#endif
+       return 0;
+}
 
-       return __kuap_get_and_assert_locked();
+static __always_inline void kuap_assert_locked(void)
+{
+       if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
+               kuap_get_and_assert_locked();
 }
 
 #ifndef CONFIG_PPC_BOOK3S_64

diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index 8579210f2a6a3a44c5f72200878f184bf0a060d9..a372cd822887b41eba9f10f69e2255b6d6421a35 100644 (file)
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -20,15 +20,12 @@ static __always_inline bool kuap_is_disabled(void)
        return static_branch_unlikely(&disable_kuap_key);
 }
 
-static inline void __kuap_lock(void)
-{
-}
-
 static inline void __kuap_save_and_lock(struct pt_regs *regs)
 {
        regs->kuap = mfspr(SPRN_MD_AP);
        mtspr(SPRN_MD_AP, MD_APG_KUAP);
 }
+#define __kuap_save_and_lock __kuap_save_and_lock
 
 static inline void kuap_user_restore(struct pt_regs *regs)
 {
@@ -39,13 +36,15 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kua
        mtspr(SPRN_MD_AP, regs->kuap);
 }
 
+#ifdef CONFIG_PPC_KUAP_DEBUG
 static inline unsigned long __kuap_get_and_assert_locked(void)
 {
-       if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
-               WARN_ON_ONCE(mfspr(SPRN_MD_AP) >> 16 != MD_APG_KUAP >> 16);
+       WARN_ON_ONCE(mfspr(SPRN_MD_AP) >> 16 != MD_APG_KUAP >> 16);
 
        return 0;
 }
+#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
+#endif
 
 static inline void __allow_user_access(void __user *to, const void __user *from,
                                       unsigned long size, unsigned long dir)

diff --git a/arch/powerpc/include/asm/nohash/kup-booke.h b/arch/powerpc/include/asm/nohash/kup-booke.h
index 823c5a3a96d8062aa93aaa93d88fa0c251f1903d..71182cbe20c3e9d2fc5aa833af8adce31c739a73 100644 (file)
--- a/arch/powerpc/include/asm/nohash/kup-booke.h
+++ b/arch/powerpc/include/asm/nohash/kup-booke.h
@@ -30,6 +30,7 @@ static inline void __kuap_lock(void)
        mtspr(SPRN_PID, 0);
        isync();
 }
+#define __kuap_lock __kuap_lock
 
 static inline void __kuap_save_and_lock(struct pt_regs *regs)
 {
@@ -37,6 +38,7 @@ static inline void __kuap_save_and_lock(struct pt_regs *regs)
        mtspr(SPRN_PID, 0);
        isync();
 }
+#define __kuap_save_and_lock __kuap_save_and_lock
 
 static inline void kuap_user_restore(struct pt_regs *regs)
 {
@@ -56,13 +58,15 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kua
        /* Context synchronisation is performed by rfi */
 }
 
+#ifdef CONFIG_PPC_KUAP_DEBUG
 static inline unsigned long __kuap_get_and_assert_locked(void)
 {
-       if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
-               WARN_ON_ONCE(mfspr(SPRN_PID));
+       WARN_ON_ONCE(mfspr(SPRN_PID));
 
        return 0;
 }
+#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
+#endif
 
 static inline void __allow_user_access(void __user *to, const void __user *from,
                                       unsigned long size, unsigned long dir)