microblaze: Support unaligned address for put/get_user macros

This patch add support for cases where load/store instruction
in put/get_user macro gets unaligned pointer to data and this
address is not valid. I prevent all cases which can failed.
I had to disable first stage of unaligned handler which is used
only for noMMU kernel and the whole work is done when interrupt
is enabled.
You have enable HW support for detect unaligned access in Microblaze.

This patch fixed three LTP tests:
getpeername01, getsockname01, socketpair01
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/hw_exception_handler.S

@@ -74,6 +74,7 @@
 
 #include <asm/mmu.h>
 #include <asm/pgtable.h>
+#include <asm/signal.h>
 #include <asm/asm-offsets.h>
 
 /* Helpful Macros */
@@ -428,19 +429,9 @@ handle_unaligned_ex:
 	mfs	r17, rbtr;	/* ESR[DS] set - return address in BTR */
 	nop
 _no_delayslot:
-#endif
-
-#ifdef CONFIG_MMU
-	/* Check if unaligned address is last on a 4k page */
-		andi	r5, r4, 0xffc
-		xori	r5, r5, 0xffc
-		bnei	r5, _unaligned_ex2
-	_unaligned_ex1:
-		RESTORE_STATE;
-/* Another page must be accessed or physical address not in page table */
-		bri	unaligned_data_trap
-
-	_unaligned_ex2:
+	/* jump to high level unaligned handler */
+	RESTORE_STATE;
+	bri	unaligned_data_trap
 #endif
 	andi	r6, r3, 0x3E0; /* Mask and extract the register operand */
 	srl	r6, r6; /* r6 >> 5 */
@@ -450,45 +441,6 @@ _no_delayslot:
 	srl	r6, r6;
 	/* Store the register operand in a temporary location */
 	sbi	r6, r0, TOPHYS(ex_reg_op);
-#ifdef CONFIG_MMU
-	/* Get physical address */
-	/* If we are faulting a kernel address, we have to use the
-	 * kernel page tables.
-	 */
-	ori	r5, r0, CONFIG_KERNEL_START
-	cmpu	r5, r4, r5
-	bgti	r5, _unaligned_ex3
-	ori	r5, r0, swapper_pg_dir
-	bri	_unaligned_ex4
-
-	/* Get the PGD for the current thread. */
-_unaligned_ex3: /* user thread */
-	addi	r5 ,CURRENT_TASK, TOPHYS(0); /* get current task address */
-	lwi	r5, r5, TASK_THREAD + PGDIR
-_unaligned_ex4:
-	tophys(r5,r5)
-	BSRLI(r6,r4,20)			/* Create L1 (pgdir/pmd) address */
-	andi	r6, r6, 0xffc
-/* Assume pgdir aligned on 4K boundary, no need for "andi r5,r5,0xfffff003" */
-	or	r5, r5, r6
-	lwi	r6, r5, 0		/* Get L1 entry */
-	andi	r5, r6, 0xfffff000	/* Extract L2 (pte) base address. */
-	beqi	r5, _unaligned_ex1	/* Bail if no table */
-
-	tophys(r5,r5)
-	BSRLI(r6,r4,10)			/* Compute PTE address */
-	andi	r6, r6, 0xffc
-	andi	r5, r5, 0xfffff003
-	or	r5, r5, r6
-	lwi	r5, r5, 0		/* Get Linux PTE */
-
-	andi	r6, r5, _PAGE_PRESENT
-	beqi	r6, _unaligned_ex1	/* Bail if no page */
-
-	andi	r5, r5, 0xfffff000	/* Extract RPN */
-	andi	r4, r4, 0x00000fff	/* Extract offset */
-	or	r4, r4, r5		/* Create physical address */
-#endif /* CONFIG_MMU */
 
 	andi	r6, r3, 0x400; /* Extract ESR[S] */
 	bnei	r6, ex_sw;
@@ -959,15 +911,15 @@ _unaligned_data_exception:
 	andi	r6, r3, 0x800;	/* Extract ESR[W] - delay slot */
 ex_lw_vm:
 	beqid	r6, ex_lhw_vm;
-	lbui	r5, r4, 0;	/* Exception address in r4 - delay slot */
+load1:	lbui	r5, r4, 0;	/* Exception address in r4 - delay slot */
 /* Load a word, byte-by-byte from destination address and save it in tmp space*/
 	la	r6, r0, ex_tmp_data_loc_0;
 	sbi	r5, r6, 0;
-	lbui	r5, r4, 1;
+load2:	lbui	r5, r4, 1;
 	sbi	r5, r6, 1;
-	lbui	r5, r4, 2;
+load3:	lbui	r5, r4, 2;
 	sbi	r5, r6, 2;
-	lbui	r5, r4, 3;
+load4:	lbui	r5, r4, 3;
 	sbi	r5, r6, 3;
 	brid	ex_lw_tail_vm;
 /* Get the destination register value into r3 - delay slot */
@@ -977,7 +929,7 @@ ex_lhw_vm:
 	 * save it in tmp space */
 	la	r6, r0, ex_tmp_data_loc_0;
 	sbi	r5, r6, 0;
-	lbui	r5, r4, 1;
+load5:	lbui	r5, r4, 1;
 	sbi	r5, r6, 1;
 	lhui	r3, r6, 0;	/* Get the destination register value into r3 */
 ex_lw_tail_vm:
@@ -996,22 +948,53 @@ ex_sw_tail_vm:
 	swi	r3, r5, 0;	/* Get the word - delay slot */
 	/* Store the word, byte-by-byte into destination address */
 	lbui	r3, r5, 0;
-	sbi	r3, r4, 0;
+store1:	sbi	r3, r4, 0;
 	lbui	r3, r5, 1;
-	sbi	r3, r4, 1;
+store2:	sbi	r3, r4, 1;
 	lbui	r3, r5, 2;
-	sbi	r3, r4, 2;
+store3:	sbi	r3, r4, 2;
 	lbui	r3, r5, 3;
 	brid	ret_from_exc;
-	sbi	r3, r4, 3;	/* Delay slot */
+store4:	sbi	r3, r4, 3;	/* Delay slot */
 ex_shw_vm:
 	/* Store the lower half-word, byte-by-byte into destination address */
 	lbui	r3, r5, 2;
-	sbi	r3, r4, 0;
+store5:	sbi	r3, r4, 0;
 	lbui	r3, r5, 3;
 	brid	ret_from_exc;
-	sbi	r3, r4, 1;	/* Delay slot */
+store6:	sbi	r3, r4, 1;	/* Delay slot */
 ex_sw_end_vm:			/* Exception handling of store word, ends. */
+
+/* We have to prevent cases that get/put_user macros get unaligned pointer
+ * to bad page area. We have to find out which origin instruction caused it
+ * and called fixup for that origin instruction not instruction in unaligned
+ * handler */
+ex_unaligned_fixup:
+	ori	r5, r7, 0 /* setup pointer to pt_regs */
+	lwi	r6, r7, PT_PC; /* faulting address is one instruction above */
+	addik	r6, r6, -4 /* for finding proper fixup */
+	swi	r6, r7, PT_PC; /* a save back it to PT_PC */
+	addik	r7, r0, SIGSEGV
+	/* call bad_page_fault for finding aligned fixup, fixup address is saved
+	 * in PT_PC which is used as return address from exception */
+	la	r15, r0, ret_from_exc-8 /* setup return address */
+	brid	bad_page_fault
+	nop
+
+/* We prevent all load/store because it could failed any attempt to access */
+.section __ex_table,"a";
+	.word	load1,ex_unaligned_fixup;
+	.word	load2,ex_unaligned_fixup;
+	.word	load3,ex_unaligned_fixup;
+	.word	load4,ex_unaligned_fixup;
+	.word	load5,ex_unaligned_fixup;
+	.word	store1,ex_unaligned_fixup;
+	.word	store2,ex_unaligned_fixup;
+	.word	store3,ex_unaligned_fixup;
+	.word	store4,ex_unaligned_fixup;
+	.word	store5,ex_unaligned_fixup;
+	.word	store6,ex_unaligned_fixup;
+.previous;
 .end _unaligned_data_exception
 #endif /* CONFIG_MMU */
 

arch/microblaze/mm/fault.c

@@ -69,7 +69,7 @@ static int store_updates_sp(struct pt_regs *regs)
  * It is called from do_page_fault above and from some of the procedures
  * in traps.c.
  */
-static void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
+void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
 {
 	const struct exception_table_entry *fixup;
 /* MS: no context */