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Date:      Tue, 1 Dec 2015 12:37:04 +0000 (UTC)
From:      Andrew Turner <andrew@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r291581 - head/sys/arm64/arm64
Message-ID:  <201512011237.tB1Cb4h7037215@repo.freebsd.org>
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Author: andrew
Date: Tue Dec  1 12:37:04 2015
New Revision: 291581
URL: https://svnweb.freebsd.org/changeset/base/291581

Log:
  Rework the exception entry/return functions to make them valid frames to be
  unwound through. For this we need the frame pointer (x29) to point to the
  location on the stack where we stored the previous frame pointer, and link
  register. To simplify this the stack pointer is only adjusted by addition
  and subtraction, and not through the use of post increment on loads and
  stores.
  
  The updated frame layout is:
  
  +------------+
  | lr -- x30  |
  +------------+
  | fp -- x29  | <-- x29 points at this
  +------------+
  | Trap frame |
  | ...        |
  |            | <-- sp points at this
  +------------+
  
  The only difference is the first two items, and setting of x29.
  
  Sponsored by:	ABT Systems Ltd

Modified:
  head/sys/arm64/arm64/exception.S
  head/sys/arm64/arm64/genassym.c

Modified: head/sys/arm64/arm64/exception.S
==============================================================================
--- head/sys/arm64/arm64/exception.S	Tue Dec  1 12:27:36 2015	(r291580)
+++ head/sys/arm64/arm64/exception.S	Tue Dec  1 12:37:04 2015	(r291581)
@@ -37,29 +37,32 @@ __FBSDID("$FreeBSD$");
 	mov	x18, sp
 	sub	sp, sp, #128
 .endif
-	stp	x28, x29, [sp, #-16]!
-	stp	x26, x27, [sp, #-16]!
-	stp	x24, x25, [sp, #-16]!
-	stp	x22, x23, [sp, #-16]!
-	stp	x20, x21, [sp, #-16]!
-	stp	x18, x19, [sp, #-16]!
-	stp	x16, x17, [sp, #-16]!
-	stp	x14, x15, [sp, #-16]!
-	stp	x12, x13, [sp, #-16]!
-	stp	x10, x11, [sp, #-16]!
-	stp	x8, x9, [sp, #-16]!
-	stp	x6, x7, [sp, #-16]!
-	stp	x4, x5, [sp, #-16]!
-	stp	x2, x3, [sp, #-16]!
-	stp	x0, x1, [sp, #-16]!
+	sub	sp, sp, #(TF_SIZE + 16)
+	stp	x29, x30, [sp, #(TF_SIZE)]
+	stp	x28, x29, [sp, #(TF_X + 28 * 8)]
+	stp	x26, x27, [sp, #(TF_X + 26 * 8)]
+	stp	x24, x25, [sp, #(TF_X + 24 * 8)]
+	stp	x22, x23, [sp, #(TF_X + 22 * 8)]
+	stp	x20, x21, [sp, #(TF_X + 20 * 8)]
+	stp	x18, x19, [sp, #(TF_X + 18 * 8)]
+	stp	x16, x17, [sp, #(TF_X + 16 * 8)]
+	stp	x14, x15, [sp, #(TF_X + 14 * 8)]
+	stp	x12, x13, [sp, #(TF_X + 12 * 8)]
+	stp	x10, x11, [sp, #(TF_X + 10 * 8)]
+	stp	x8,  x9,  [sp, #(TF_X + 8  * 8)]
+	stp	x6,  x7,  [sp, #(TF_X + 6  * 8)]
+	stp	x4,  x5,  [sp, #(TF_X + 4  * 8)]
+	stp	x2,  x3,  [sp, #(TF_X + 2  * 8)]
+	stp	x0,  x1,  [sp, #(TF_X + 0  * 8)]
 	mrs	x10, elr_el1
 	mrs	x11, spsr_el1
 .if \el == 0
 	mrs	x18, sp_el0
 .endif
-	stp	x10, x11, [sp, #-16]!
-	stp	x18, lr, [sp, #-16]!
+	stp	x10, x11, [sp, #(TF_ELR)]
+	stp	x18,  lr, [sp, #(TF_SP)]
 	mrs	x18, tpidr_el1
+	add	x29, sp, #(TF_SIZE)
 .endm
 
 .macro	restore_registers el
@@ -70,33 +73,35 @@ __FBSDID("$FreeBSD$");
 	 * handler.  For EL0 exceptions, do_ast already did this.
 	 */
 .endif
-	ldp	x18, lr, [sp], #16
-	ldp	x10, x11, [sp], #16
+	ldp	x18,  lr, [sp, #(TF_SP)]
+	ldp	x10, x11, [sp, #(TF_ELR)]
 .if \el == 0
 	msr	sp_el0, x18
 .endif
 	msr	spsr_el1, x11
 	msr	elr_el1, x10
-	ldp	x0, x1, [sp], #16
-	ldp	x2, x3, [sp], #16
-	ldp	x4, x5, [sp], #16
-	ldp	x6, x7, [sp], #16
-	ldp	x8, x9, [sp], #16
-	ldp	x10, x11, [sp], #16
-	ldp	x12, x13, [sp], #16
-	ldp	x14, x15, [sp], #16
-	ldp	x16, x17, [sp], #16
+	ldp	x0,  x1,  [sp, #(TF_X + 0  * 8)]
+	ldp	x2,  x3,  [sp, #(TF_X + 2  * 8)]
+	ldp	x4,  x5,  [sp, #(TF_X + 4  * 8)]
+	ldp	x6,  x7,  [sp, #(TF_X + 6  * 8)]
+	ldp	x8,  x9,  [sp, #(TF_X + 8  * 8)]
+	ldp	x10, x11, [sp, #(TF_X + 10 * 8)]
+	ldp	x12, x13, [sp, #(TF_X + 12 * 8)]
+	ldp	x14, x15, [sp, #(TF_X + 14 * 8)]
+	ldp	x16, x17, [sp, #(TF_X + 16 * 8)]
 .if \el == 0
-	ldp	x18, x19, [sp], #16
+	ldp	x18, x19, [sp, #(TF_X + 18 * 8)]
 .else
-	ldp	xzr, x19, [sp], #16
+	ldr	     x19, [sp, #(TF_X + 19 * 8)]
 .endif
-	ldp	x20, x21, [sp], #16
-	ldp	x22, x23, [sp], #16
-	ldp	x24, x25, [sp], #16
-	ldp	x26, x27, [sp], #16
-	ldp	x28, x29, [sp], #16
-.if \el == 1
+	ldp	x20, x21, [sp, #(TF_X + 20 * 8)]
+	ldp	x22, x23, [sp, #(TF_X + 22 * 8)]
+	ldp	x24, x25, [sp, #(TF_X + 24 * 8)]
+	ldp	x26, x27, [sp, #(TF_X + 26 * 8)]
+	ldp	x28, x29, [sp, #(TF_X + 28 * 8)]
+.if \el == 0
+	add	sp, sp, #(TF_SIZE + 16)
+.else
 	mov	sp, x18
 	mrs	x18, tpidr_el1
 .endif

Modified: head/sys/arm64/arm64/genassym.c
==============================================================================
--- head/sys/arm64/arm64/genassym.c	Tue Dec  1 12:27:36 2015	(r291580)
+++ head/sys/arm64/arm64/genassym.c	Tue Dec  1 12:37:04 2015	(r291581)
@@ -60,4 +60,7 @@ ASSYM(TD_PCB, offsetof(struct thread, td
 ASSYM(TD_FLAGS, offsetof(struct thread, td_flags));
 ASSYM(TD_LOCK, offsetof(struct thread, td_lock));
 
+ASSYM(TF_SIZE, sizeof(struct trapframe));
+ASSYM(TF_SP, offsetof(struct trapframe, tf_sp));
+ASSYM(TF_ELR, offsetof(struct trapframe, tf_elr));
 ASSYM(TF_X, offsetof(struct trapframe, tf_x));

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