powerpc/mm: Move the WARN() out of bad_kuap_fault()

In order to prepare the removal of calls to
search_exception_tables() on the fast path, move the
WARN() out of bad_kuap_fault().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/9501311014bd6507e04b27a0c3035186ccf65cd5.1607491748.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 32fd4452e9602952effba181d08f8892050069ae..a0117a9d5b06cd45ac4ed317d0a2410cc890e0ad 100644 (file)
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -183,11 +183,7 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
        unsigned long begin = regs->kuap & 0xf0000000;
        unsigned long end = regs->kuap << 28;
 
-       if (!is_write)
-               return false;
-
-       return WARN(address < begin || address >= end,
-                   "Bug: write fault blocked by segment registers !");
+       return is_write && (address < begin || address >= end);
 }
 
 #endif /* CONFIG_PPC_KUAP */

diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 7075c92c320ce4ec6e04d5d8eaca94731066868b..f50f72e535aad97a78bdef0f959f6454c4e1409e 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -371,11 +371,9 @@ static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address,
         * the AMR. Hence check for BLOCK_WRITE/READ against AMR.
         */
        if (is_write) {
-               return WARN(((regs->amr & AMR_KUAP_BLOCK_WRITE) == AMR_KUAP_BLOCK_WRITE),
-                           "Bug: Write fault blocked by AMR!");
+               return (regs->amr & AMR_KUAP_BLOCK_WRITE) == AMR_KUAP_BLOCK_WRITE;
        }
-       return WARN(((regs->amr & AMR_KUAP_BLOCK_READ) == AMR_KUAP_BLOCK_READ),
-                   "Bug: Read fault blocked by AMR!");
+       return (regs->amr & AMR_KUAP_BLOCK_READ) == AMR_KUAP_BLOCK_READ;
 }
 
 static __always_inline void allow_user_access(void __user *to, const void __user *from,

diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index 567cdc55740241c653c56f3e5f37b4fc2a178098..17a4a616436ffa51a43bdd8a515546e33356707f 100644 (file)
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -63,8 +63,7 @@ static inline void restore_user_access(unsigned long flags)
 static inline bool
 bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
 {
-       return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xff000000),
-                   "Bug: fault blocked by AP register !");
+       return !((regs->kuap ^ MD_APG_KUAP) & 0xff000000);
 }
 
 #endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 3fcd34c28e1061da8c7d32e3213920bb51bce0af..04505f938bbc732924f70e32b1f05ca6f0411e1e 100644 (file)
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -228,7 +228,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
        // Read/write fault in a valid region (the exception table search passed
        // above), but blocked by KUAP is bad, it can never succeed.
        if (bad_kuap_fault(regs, address, is_write))
-               return true;
+               return WARN(true, "Bug: %s fault blocked by KUAP!", is_write ? "Write" : "Read");
 
        // What's left? Kernel fault on user in well defined regions (extable
        // matched), and allowed by KUAP in the faulting context.