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+/*
+ * arch/xtensa/kernel/coprocessor.S
+ *
+ * Xtensa processor configuration-specific table of coprocessor and
+ * other custom register layout information.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2003 - 2007 Tensilica Inc.
+ */
+
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/asmmacro.h>
+#include <asm/coprocessor.h>
+#include <asm/current.h>
+#include <asm/regs.h>
+
+/*
+ * Rules for coprocessor state manipulation on SMP:
+ *
+ * - a task may have live coprocessors only on one CPU.
+ *
+ * - whether coprocessor context of task T is live on some CPU is
+ * denoted by T's thread_info->cpenable.
+ *
+ * - non-zero thread_info->cpenable means that thread_info->cp_owner_cpu
+ * is valid in the T's thread_info. Zero thread_info->cpenable means that
+ * coprocessor context is valid in the T's thread_info.
+ *
+ * - if a coprocessor context of task T is live on CPU X, only CPU X changes
+ * T's thread_info->cpenable, cp_owner_cpu and coprocessor save area.
+ * This is done by making sure that for the task T with live coprocessor
+ * on CPU X cpenable SR is 0 when T runs on any other CPU Y.
+ * When fast_coprocessor exception is taken on CPU Y it goes to the
+ * C-level do_coprocessor that uses IPI to make CPU X flush T's coprocessors.
+ */
+
+#if XTENSA_HAVE_COPROCESSORS
+
+/*
+ * Macros for lazy context switch.
+ */
+
+#define SAVE_CP_REGS(x) \
+ .if XTENSA_HAVE_COPROCESSOR(x); \
+ .align 4; \
+ .Lsave_cp_regs_cp##x: \
+ xchal_cp##x##_store a2 a3 a4 a5 a6; \
+ ret; \
+ .endif
+
+#define LOAD_CP_REGS(x) \
+ .if XTENSA_HAVE_COPROCESSOR(x); \
+ .align 4; \
+ .Lload_cp_regs_cp##x: \
+ xchal_cp##x##_load a2 a3 a4 a5 a6; \
+ ret; \
+ .endif
+
+#define CP_REGS_TAB(x) \
+ .if XTENSA_HAVE_COPROCESSOR(x); \
+ .long .Lsave_cp_regs_cp##x; \
+ .long .Lload_cp_regs_cp##x; \
+ .else; \
+ .long 0, 0; \
+ .endif; \
+ .long THREAD_XTREGS_CP##x
+
+#define CP_REGS_TAB_SAVE 0
+#define CP_REGS_TAB_LOAD 4
+#define CP_REGS_TAB_OFFSET 8
+
+ __XTENSA_HANDLER
+
+ SAVE_CP_REGS(0)
+ SAVE_CP_REGS(1)
+ SAVE_CP_REGS(2)
+ SAVE_CP_REGS(3)
+ SAVE_CP_REGS(4)
+ SAVE_CP_REGS(5)
+ SAVE_CP_REGS(6)
+ SAVE_CP_REGS(7)
+
+ LOAD_CP_REGS(0)
+ LOAD_CP_REGS(1)
+ LOAD_CP_REGS(2)
+ LOAD_CP_REGS(3)
+ LOAD_CP_REGS(4)
+ LOAD_CP_REGS(5)
+ LOAD_CP_REGS(6)
+ LOAD_CP_REGS(7)
+
+ .align 4
+.Lcp_regs_jump_table:
+ CP_REGS_TAB(0)
+ CP_REGS_TAB(1)
+ CP_REGS_TAB(2)
+ CP_REGS_TAB(3)
+ CP_REGS_TAB(4)
+ CP_REGS_TAB(5)
+ CP_REGS_TAB(6)
+ CP_REGS_TAB(7)
+
+/*
+ * Entry condition:
+ *
+ * a0: trashed, original value saved on stack (PT_AREG0)
+ * a1: a1
+ * a2: new stack pointer, original in DEPC
+ * a3: a3
+ * depc: a2, original value saved on stack (PT_DEPC)
+ * excsave_1: dispatch table
+ *
+ * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
+ * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
+ */
+
+ENTRY(fast_coprocessor)
+
+ s32i a3, a2, PT_AREG3
+
+#ifdef CONFIG_SMP
+ /*
+ * Check if any coprocessor context is live on another CPU
+ * and if so go through the C-level coprocessor exception handler
+ * to flush it to memory.
+ */
+ GET_THREAD_INFO (a0, a2)
+ l32i a3, a0, THREAD_CPENABLE
+ beqz a3, .Lload_local
+
+ /*
+ * Pairs with smp_wmb in local_coprocessor_release_all
+ * and with both memws below.
+ */
+ memw
+ l32i a3, a0, THREAD_CPU
+ l32i a0, a0, THREAD_CP_OWNER_CPU
+ beq a0, a3, .Lload_local
+
+ rsr a0, ps
+ l32i a3, a2, PT_AREG3
+ bbci.l a0, PS_UM_BIT, 1f
+ call0 user_exception
+1: call0 kernel_exception
+#endif
+
+ /* Save remaining registers a1-a3 and SAR */
+
+.Lload_local:
+ rsr a3, sar
+ s32i a1, a2, PT_AREG1
+ s32i a3, a2, PT_SAR
+ mov a1, a2
+ rsr a2, depc
+ s32i a2, a1, PT_AREG2
+
+ /* The hal macros require up to 4 temporary registers. We use a3..a6. */
+
+ s32i a4, a1, PT_AREG4
+ s32i a5, a1, PT_AREG5
+ s32i a6, a1, PT_AREG6
+ s32i a7, a1, PT_AREG7
+ s32i a8, a1, PT_AREG8
+ s32i a9, a1, PT_AREG9
+ s32i a10, a1, PT_AREG10
+
+ /* Find coprocessor number. Subtract first CP EXCCAUSE from EXCCAUSE */
+
+ rsr a3, exccause
+ addi a3, a3, -EXCCAUSE_COPROCESSOR0_DISABLED
+
+ /* Set corresponding CPENABLE bit -> (sar:cp-index, a3: 1<<cp-index)*/
+
+ ssl a3 # SAR: 32 - coprocessor_number
+ movi a2, 1
+ rsr a0, cpenable
+ sll a2, a2
+ or a0, a0, a2
+ wsr a0, cpenable
+ rsync
+
+ /* Get coprocessor save/load table entry (a7). */
+
+ movi a7, .Lcp_regs_jump_table
+ addx8 a7, a3, a7
+ addx4 a7, a3, a7
+
+ /* Retrieve previous owner (a8). */
+
+ rsr a0, excsave1 # exc_table
+ addx4 a0, a3, a0 # entry for CP
+ l32i a8, a0, EXC_TABLE_COPROCESSOR_OWNER
+
+ /* Set new owner (a9). */
+
+ GET_THREAD_INFO (a9, a1)
+ l32i a4, a9, THREAD_CPU
+ s32i a9, a0, EXC_TABLE_COPROCESSOR_OWNER
+ s32i a4, a9, THREAD_CP_OWNER_CPU
+
+ /*
+ * Enable coprocessor for the new owner. (a2 = 1 << CP number)
+ * This can be done before loading context into the coprocessor.
+ */
+ l32i a4, a9, THREAD_CPENABLE
+ or a4, a4, a2
+
+ /*
+ * Make sure THREAD_CP_OWNER_CPU is in memory before updating
+ * THREAD_CPENABLE
+ */
+ memw # (2)
+ s32i a4, a9, THREAD_CPENABLE
+
+ beqz a8, 1f # skip 'save' if no previous owner
+
+ /* Disable coprocessor for previous owner. (a2 = 1 << CP number) */
+
+ l32i a10, a8, THREAD_CPENABLE
+ xor a10, a10, a2
+
+ /* Get context save area and call save routine. */
+
+ l32i a2, a7, CP_REGS_TAB_OFFSET
+ l32i a3, a7, CP_REGS_TAB_SAVE
+ add a2, a2, a8
+ callx0 a3
+
+ /*
+ * Make sure coprocessor context and THREAD_CP_OWNER_CPU are in memory
+ * before updating THREAD_CPENABLE
+ */
+ memw # (3)
+ s32i a10, a8, THREAD_CPENABLE
+1:
+ /* Get context save area and call load routine. */
+
+ l32i a2, a7, CP_REGS_TAB_OFFSET
+ l32i a3, a7, CP_REGS_TAB_LOAD
+ add a2, a2, a9
+ callx0 a3
+
+ /* Restore all registers and return from exception handler. */
+
+ l32i a10, a1, PT_AREG10
+ l32i a9, a1, PT_AREG9
+ l32i a8, a1, PT_AREG8
+ l32i a7, a1, PT_AREG7
+ l32i a6, a1, PT_AREG6
+ l32i a5, a1, PT_AREG5
+ l32i a4, a1, PT_AREG4
+
+ l32i a0, a1, PT_SAR
+ l32i a3, a1, PT_AREG3
+ l32i a2, a1, PT_AREG2
+ wsr a0, sar
+ l32i a0, a1, PT_AREG0
+ l32i a1, a1, PT_AREG1
+
+ rfe
+
+ENDPROC(fast_coprocessor)
+
+ .text
+
+/*
+ * coprocessor_flush(struct thread_info*, index)
+ * a2 a3
+ *
+ * Save coprocessor registers for coprocessor 'index'.
+ * The register values are saved to or loaded from the coprocessor area
+ * inside the task_info structure.
+ *
+ * Note that this function doesn't update the coprocessor_owner information!
+ *
+ */
+
+ENTRY(coprocessor_flush)
+
+ abi_entry_default
+
+ movi a4, .Lcp_regs_jump_table
+ addx8 a4, a3, a4
+ addx4 a3, a3, a4
+ l32i a4, a3, CP_REGS_TAB_SAVE
+ beqz a4, 1f
+ l32i a3, a3, CP_REGS_TAB_OFFSET
+ add a2, a2, a3
+ mov a7, a0
+ callx0 a4
+ mov a0, a7
+1:
+ abi_ret_default
+
+ENDPROC(coprocessor_flush)
+
+#endif /* XTENSA_HAVE_COPROCESSORS */