xtensa: add MMU v3 support

MMUv3 comes out of reset with identity vaddr -> paddr mapping in the TLB
way 6:

Way 6 (512 MB)
        Vaddr       Paddr       ASID  Attr RWX Cache
        ----------  ----------  ----  ---- --- -------
        0x00000000  0x00000000  0x01  0x03 RWX Bypass
        0x20000000  0x20000000  0x01  0x03 RWX Bypass
        0x40000000  0x40000000  0x01  0x03 RWX Bypass
        0x60000000  0x60000000  0x01  0x03 RWX Bypass
        0x80000000  0x80000000  0x01  0x03 RWX Bypass
        0xa0000000  0xa0000000  0x01  0x03 RWX Bypass
        0xc0000000  0xc0000000  0x01  0x03 RWX Bypass
        0xe0000000  0xe0000000  0x01  0x03 RWX Bypass

This patch adds remapping code at the reset vector or at the kernel
_start (depending on CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX) that
reconfigures MMUv3 as MMUv2:

Way 5 (128 MB)
        Vaddr       Paddr       ASID  Attr RWX Cache
        ----------  ----------  ----  ---- --- -------
        0xd0000000  0x00000000  0x01  0x07 RWX WB
        0xd8000000  0x00000000  0x01  0x03 RWX Bypass
Way 6 (256 MB)
        Vaddr       Paddr       ASID  Attr RWX Cache
        ----------  ----------  ----  ---- --- -------
        0xe0000000  0xf0000000  0x01  0x07 RWX WB
        0xf0000000  0xf0000000  0x01  0x03 RWX Bypass

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

4 files changed, 63 insertions, 27 deletions

diff --git a/arch/xtensa/kernel/Makefile b/arch/xtensa/kernel/Makefile
index c3a59d9..c433a56 100644
--- a/arch/xtensa/kernel/Makefile
+++ b/arch/xtensa/kernel/Makefile
@@ -12,6 +12,8 @@ obj-$(CONFIG_KGDB) += xtensa-stub.o
 obj-$(CONFIG_PCI) += pci.o
 obj-$(CONFIG_MODULES) += xtensa_ksyms.o module.o
 
+AFLAGS_head.o += -mtext-section-literals
+
 # In the Xtensa architecture, assembly generates literals which must always
 # precede the L32R instruction with a relative offset less than 256 kB.
 # Therefore, the .text and .literal section must be combined in parenthesis
diff --git a/arch/xtensa/kernel/head.S b/arch/xtensa/kernel/head.S
index 4566683..ef12c0e 100644
--- a/arch/xtensa/kernel/head.S
+++ b/arch/xtensa/kernel/head.S
@@ -48,17 +48,36 @@
 	 */
 
 	__HEAD
+	.begin	no-absolute-literals
+
 ENTRY(_start)
 
-	_j	2f
+	/* Preserve the pointer to the boot parameter list in EXCSAVE_1 */
+	wsr     a2, excsave1
+	_j	_SetupMMU
+
+	.align	4
+	.literal_position
+.Lstartup:
+	.word	_startup
+
 	.align	4
-1:	.word	_startup
-2:	l32r	a0, 1b
+	.global _SetupMMU
+_SetupMMU:
+	Offset = _SetupMMU - _start
+
+#ifdef CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+	initialize_mmu
+#endif
+	.end	no-absolute-literals
+
+	l32r	a0, .Lstartup
 	jx	a0
 
 ENDPROC(_start)
 
-	.section .init.text, "ax"
+	__INIT
+	.literal_position
 
 ENTRY(_startup)
 
@@ -67,10 +86,6 @@ ENTRY(_startup)
 	movi	a0, LOCKLEVEL
 	wsr	a0, ps
 
-	/* Preserve the pointer to the boot parameter list in EXCSAVE_1 */
-
-	wsr	a2, excsave1
-
 	/* Start with a fresh windowbase and windowstart.  */
 
 	movi	a1, 1
@@ -158,8 +173,6 @@ ENTRY(_startup)
 
 	isync
 
-	initialize_mmu
-
 	/* Unpack data sections
 	 *
 	 * The linker script used to build the Linux kernel image
@@ -207,6 +220,10 @@ ENTRY(_startup)
 
 	___flush_dcache_all a2 a3
 #endif
+	memw
+	isync
+	___invalidate_icache_all a2 a3
+	isync
 
 	/* Setup stack and enable window exceptions (keep irqs disabled) */
 
diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S
index 82109b42..a7e1d08 100644
--- a/arch/xtensa/kernel/vectors.S
+++ b/arch/xtensa/kernel/vectors.S
@@ -50,6 +50,7 @@
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/thread_info.h>
+#include <asm/vectors.h>
 
 #define WINDOW_VECTORS_SIZE   0x180
 
@@ -220,7 +221,7 @@ ENTRY(_DoubleExceptionVector)
 
 	xsr	a0, depc		# get DEPC, save a0
 
-	movi	a3, XCHAL_WINDOW_VECTORS_VADDR
+	movi	a3, WINDOW_VECTORS_VADDR
 	_bltu	a0, a3, .Lfixup
 	addi	a3, a3, WINDOW_VECTORS_SIZE
 	_bgeu	a0, a3, .Lfixup
diff --git a/arch/xtensa/kernel/vmlinux.lds.S b/arch/xtensa/kernel/vmlinux.lds.S
index 1469524..21acd11 100644
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -18,6 +18,7 @@
 #include <asm/page.h>
 #include <asm/thread_info.h>
 
+#include <asm/vectors.h>
 #include <variant/core.h>
 #include <platform/hardware.h>
 OUTPUT_ARCH(xtensa)
@@ -30,7 +31,7 @@ jiffies = jiffies_64;
 #endif
 
 #ifndef KERNELOFFSET
-#define KERNELOFFSET 0xd0001000
+#define KERNELOFFSET 0xd0003000
 #endif
 
 /* Note: In the following macros, it would be nice to specify only the
@@ -185,16 +186,16 @@ SECTIONS
 
   SECTION_VECTOR (_WindowVectors_text,
 		  .WindowVectors.text,
-		  XCHAL_WINDOW_VECTORS_VADDR, 4,
+		  WINDOW_VECTORS_VADDR, 4,
 		  .dummy)
   SECTION_VECTOR (_DebugInterruptVector_literal,
 		  .DebugInterruptVector.literal,
-		  XCHAL_DEBUG_VECTOR_VADDR - 4,
+		  DEBUG_VECTOR_VADDR - 4,
 		  SIZEOF(.WindowVectors.text),
 		  .WindowVectors.text)
   SECTION_VECTOR (_DebugInterruptVector_text,
 		  .DebugInterruptVector.text,
-		  XCHAL_DEBUG_VECTOR_VADDR,
+		  DEBUG_VECTOR_VADDR,
 		  4,
 		  .DebugInterruptVector.literal)
 #undef LAST
@@ -202,7 +203,7 @@ SECTIONS
 #if XCHAL_EXCM_LEVEL >= 2
   SECTION_VECTOR (_Level2InterruptVector_text,
 		  .Level2InterruptVector.text,
-		  XCHAL_INTLEVEL2_VECTOR_VADDR,
+		  INTLEVEL2_VECTOR_VADDR,
 		  SIZEOF(LAST), LAST)
 # undef LAST
 # define LAST	.Level2InterruptVector.text
@@ -210,7 +211,7 @@ SECTIONS
 #if XCHAL_EXCM_LEVEL >= 3
   SECTION_VECTOR (_Level3InterruptVector_text,
 		  .Level3InterruptVector.text,
-		  XCHAL_INTLEVEL3_VECTOR_VADDR,
+		  INTLEVEL3_VECTOR_VADDR,
 		  SIZEOF(LAST), LAST)
 # undef LAST
 # define LAST	.Level3InterruptVector.text
@@ -218,7 +219,7 @@ SECTIONS
 #if XCHAL_EXCM_LEVEL >= 4
   SECTION_VECTOR (_Level4InterruptVector_text,
 		  .Level4InterruptVector.text,
-		  XCHAL_INTLEVEL4_VECTOR_VADDR,
+		  INTLEVEL4_VECTOR_VADDR,
 		  SIZEOF(LAST), LAST)
 # undef LAST
 # define LAST	.Level4InterruptVector.text
@@ -226,7 +227,7 @@ SECTIONS
 #if XCHAL_EXCM_LEVEL >= 5
   SECTION_VECTOR (_Level5InterruptVector_text,
 		  .Level5InterruptVector.text,
-		  XCHAL_INTLEVEL5_VECTOR_VADDR,
+		  INTLEVEL5_VECTOR_VADDR,
 		  SIZEOF(LAST), LAST)
 # undef LAST
 # define LAST	.Level5InterruptVector.text
@@ -234,39 +235,39 @@ SECTIONS
 #if XCHAL_EXCM_LEVEL >= 6
   SECTION_VECTOR (_Level6InterruptVector_text,
 		  .Level6InterruptVector.text,
-		  XCHAL_INTLEVEL6_VECTOR_VADDR,
+		  INTLEVEL6_VECTOR_VADDR,
 		  SIZEOF(LAST), LAST)
 # undef LAST
 # define LAST	.Level6InterruptVector.text
 #endif
   SECTION_VECTOR (_KernelExceptionVector_literal,
 		  .KernelExceptionVector.literal,
-		  XCHAL_KERNEL_VECTOR_VADDR - 4,
+		  KERNEL_VECTOR_VADDR - 4,
 		  SIZEOF(LAST), LAST)
 #undef LAST
   SECTION_VECTOR (_KernelExceptionVector_text,
 		  .KernelExceptionVector.text,
-		  XCHAL_KERNEL_VECTOR_VADDR,
+		  KERNEL_VECTOR_VADDR,
 		  4,
 		  .KernelExceptionVector.literal)
   SECTION_VECTOR (_UserExceptionVector_literal,
 		  .UserExceptionVector.literal,
-		  XCHAL_USER_VECTOR_VADDR - 4,
+		  USER_VECTOR_VADDR - 4,
 		  SIZEOF(.KernelExceptionVector.text),
 		  .KernelExceptionVector.text)
   SECTION_VECTOR (_UserExceptionVector_text,
 		  .UserExceptionVector.text,
-		  XCHAL_USER_VECTOR_VADDR,
+		  USER_VECTOR_VADDR,
 		  4,
 		  .UserExceptionVector.literal)
   SECTION_VECTOR (_DoubleExceptionVector_literal,
 		  .DoubleExceptionVector.literal,
-		  XCHAL_DOUBLEEXC_VECTOR_VADDR - 16,
+		  DOUBLEEXC_VECTOR_VADDR - 16,
 		  SIZEOF(.UserExceptionVector.text),
 		  .UserExceptionVector.text)
   SECTION_VECTOR (_DoubleExceptionVector_text,
 		  .DoubleExceptionVector.text,
-		  XCHAL_DOUBLEEXC_VECTOR_VADDR,
+		  DOUBLEEXC_VECTOR_VADDR,
 		  32,
 		  .DoubleExceptionVector.literal)
 
@@ -284,11 +285,26 @@ SECTIONS
   . = ALIGN(0x10);
   .bootstrap : { *(.bootstrap.literal .bootstrap.text .bootstrap.data) }
 
-  .ResetVector.text XCHAL_RESET_VECTOR_VADDR :
+  .ResetVector.text RESET_VECTOR_VADDR :
   {
     *(.ResetVector.text)
   }
 
+
+  /*
+   * This is a remapped copy of the Secondary Reset Vector Code.
+   * It keeps gdb in sync with the PC after switching
+   * to the temporary mapping used while setting up
+   * the V2 MMU mappings for Linux.
+   *
+   * Only debug information about this section is put in the kernel image.
+   */
+  .SecondaryResetVector.remapped_text 0x46000000 (INFO):
+  {
+	*(.SecondaryResetVector.remapped_text)
+  }
+
+
   .xt.lit : { *(.xt.lit) }
   .xt.prop : { *(.xt.prop) }