XScale: context restore, cleanup/bugfix

This "loop over all registers" routine shared the same mess as
full_context() in terms of dozens of needless number_to_mode()
calls.  Fix that, and comments, with related cleanup.

The misnamed xscale_restore_context() had a related bug.  It
was restoring the *WRONG REGISTERS* ... always from whatever
the current mode was, instead of using the copy from whichever
register bank it was trying to restore.  (But it marked the
intended register as having been restored...)  Fixed that.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

1 files changed, 29 insertions, 15 deletions

diff --git a/src/target/xscale.c b/src/target/xscale.c
index bf5d0afa..0680c520 100644
--- a/src/target/xscale.c
+++ b/src/target/xscale.c
@@ -1768,37 +1768,45 @@ static int xscale_restore_context(struct target *target)
 	}
 
 	/* iterate through processor modes (FIQ, IRQ, SVC, ABT, UND and SYS)
-	* we can't enter User mode on an XScale (unpredictable),
-	* but User shares registers with SYS
-	*/
+	 * and check if any banked registers need to be written.  Ignore
+	 * USR mode (number 0) in favor of SYS; we can't enter User mode on
+	 * an XScale (unpredictable), but they share all registers.
+	 */
 	for (i = 1; i < 7; i++)
 	{
 		int dirty = 0;
+		enum armv4_5_mode mode = armv4_5_number_to_mode(i);
 
-		/* check if there are invalid registers in the current mode
-		*/
+		if (mode == ARMV4_5_MODE_USR)
+			continue;
+
+		/* check if there are dirty registers in this mode */
 		for (j = 8; j <= 14; j++)
 		{
-			if (ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_number_to_mode(i), j).dirty == 1)
+			if (ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
+					mode, j).dirty)
 				dirty = 1;
 		}
 
 		/* if not USR/SYS, check if the SPSR needs to be written */
-		if ((armv4_5_number_to_mode(i) != ARMV4_5_MODE_USR) && (armv4_5_number_to_mode(i) != ARMV4_5_MODE_SYS))
+		if (mode != ARMV4_5_MODE_SYS)
 		{
-			if (ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_number_to_mode(i), 16).dirty == 1)
+			if (ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
+					mode, 16).dirty)
 				dirty = 1;
 		}
 
+		/* is there anything to flush for this mode? */
 		if (dirty)
 		{
 			uint32_t tmp_cpsr;
+			struct reg *r;
 
-			/* send banked registers */
+			/* command 0x1:  "send banked registers" */
 			xscale_send_u32(target, 0x1);
 
 			tmp_cpsr = 0x0;
-			tmp_cpsr |= armv4_5_number_to_mode(i);
+			tmp_cpsr |= mode;
 			tmp_cpsr |= 0xc0; /* I/F bits */
 
 			/* send CPSR for desired mode */
@@ -1807,14 +1815,20 @@ static int xscale_restore_context(struct target *target)
 			/* send banked registers, r8 to r14, and spsr if not in USR/SYS mode */
 			for (j = 8; j <= 14; j++)
 			{
-				xscale_send_u32(target, buf_get_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5->core_mode, j).value, 0, 32));
-				ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_number_to_mode(i), j).dirty = 0;
+				r = &ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
+						mode, j);
+				xscale_send_u32(target,
+						buf_get_u32(r->value, 0, 32));
+				r->dirty = false;
 			}
 
-			if ((armv4_5_number_to_mode(i) != ARMV4_5_MODE_USR) && (armv4_5_number_to_mode(i) != ARMV4_5_MODE_SYS))
+			if (mode != ARMV4_5_MODE_SYS)
 			{
-				xscale_send_u32(target, buf_get_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5->core_mode, 16).value, 0, 32));
-				ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_number_to_mode(i), 16).dirty = 0;
+				r = &ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
+						mode, 16);
+				xscale_send_u32(target,
+						buf_get_u32(r->value, 0, 32));
+				r->dirty = false;
 			}
 		}
 	}