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-rw-r--r--arch/loongarch/kernel/lbt.S155
1 files changed, 155 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/lbt.S b/arch/loongarch/kernel/lbt.S
new file mode 100644
index 000000000000..9c75120a26d8
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+++ b/arch/loongarch/kernel/lbt.S
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Author: Qi Hu <huqi@loongson.cn>
+ * Huacai Chen <chenhuacai@loongson.cn>
+ *
+ * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
+ */
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/asm-extable.h>
+#include <asm/asm-offsets.h>
+#include <asm/errno.h>
+#include <asm/regdef.h>
+
+#define SCR_REG_WIDTH 8
+
+ .macro EX insn, reg, src, offs
+.ex\@: \insn \reg, \src, \offs
+ _asm_extable .ex\@, .L_lbt_fault
+ .endm
+
+/*
+ * Save a thread's lbt context.
+ */
+SYM_FUNC_START(_save_lbt)
+ movscr2gr t1, $scr0 # save scr
+ stptr.d t1, a0, THREAD_SCR0
+ movscr2gr t1, $scr1
+ stptr.d t1, a0, THREAD_SCR1
+ movscr2gr t1, $scr2
+ stptr.d t1, a0, THREAD_SCR2
+ movscr2gr t1, $scr3
+ stptr.d t1, a0, THREAD_SCR3
+
+ x86mfflag t1, 0x3f # save eflags
+ stptr.d t1, a0, THREAD_EFLAGS
+ jr ra
+SYM_FUNC_END(_save_lbt)
+EXPORT_SYMBOL(_save_lbt)
+
+/*
+ * Restore a thread's lbt context.
+ */
+SYM_FUNC_START(_restore_lbt)
+ ldptr.d t1, a0, THREAD_SCR0 # restore scr
+ movgr2scr $scr0, t1
+ ldptr.d t1, a0, THREAD_SCR1
+ movgr2scr $scr1, t1
+ ldptr.d t1, a0, THREAD_SCR2
+ movgr2scr $scr2, t1
+ ldptr.d t1, a0, THREAD_SCR3
+ movgr2scr $scr3, t1
+
+ ldptr.d t1, a0, THREAD_EFLAGS # restore eflags
+ x86mtflag t1, 0x3f
+ jr ra
+SYM_FUNC_END(_restore_lbt)
+EXPORT_SYMBOL(_restore_lbt)
+
+/*
+ * Load scr/eflag with zero.
+ */
+SYM_FUNC_START(_init_lbt)
+ movgr2scr $scr0, zero
+ movgr2scr $scr1, zero
+ movgr2scr $scr2, zero
+ movgr2scr $scr3, zero
+
+ x86mtflag zero, 0x3f
+ jr ra
+SYM_FUNC_END(_init_lbt)
+
+/*
+ * a0: scr
+ * a1: eflag
+ */
+SYM_FUNC_START(_save_lbt_context)
+ movscr2gr t1, $scr0 # save scr
+ EX st.d t1, a0, (0 * SCR_REG_WIDTH)
+ movscr2gr t1, $scr1
+ EX st.d t1, a0, (1 * SCR_REG_WIDTH)
+ movscr2gr t1, $scr2
+ EX st.d t1, a0, (2 * SCR_REG_WIDTH)
+ movscr2gr t1, $scr3
+ EX st.d t1, a0, (3 * SCR_REG_WIDTH)
+
+ x86mfflag t1, 0x3f # save eflags
+ EX st.w t1, a1, 0
+ li.w a0, 0 # success
+ jr ra
+SYM_FUNC_END(_save_lbt_context)
+
+/*
+ * a0: scr
+ * a1: eflag
+ */
+SYM_FUNC_START(_restore_lbt_context)
+ EX ld.d t1, a0, (0 * SCR_REG_WIDTH) # restore scr
+ movgr2scr $scr0, t1
+ EX ld.d t1, a0, (1 * SCR_REG_WIDTH)
+ movgr2scr $scr1, t1
+ EX ld.d t1, a0, (2 * SCR_REG_WIDTH)
+ movgr2scr $scr2, t1
+ EX ld.d t1, a0, (3 * SCR_REG_WIDTH)
+ movgr2scr $scr3, t1
+
+ EX ld.w t1, a1, 0 # restore eflags
+ x86mtflag t1, 0x3f
+ li.w a0, 0 # success
+ jr ra
+SYM_FUNC_END(_restore_lbt_context)
+
+/*
+ * a0: ftop
+ */
+SYM_FUNC_START(_save_ftop_context)
+ x86mftop t1
+ st.w t1, a0, 0
+ li.w a0, 0 # success
+ jr ra
+SYM_FUNC_END(_save_ftop_context)
+
+/*
+ * a0: ftop
+ */
+SYM_FUNC_START(_restore_ftop_context)
+ ld.w t1, a0, 0
+ andi t1, t1, 0x7
+ la.pcrel a0, 1f
+ alsl.d a0, t1, a0, 3
+ jr a0
+1:
+ x86mttop 0
+ b 2f
+ x86mttop 1
+ b 2f
+ x86mttop 2
+ b 2f
+ x86mttop 3
+ b 2f
+ x86mttop 4
+ b 2f
+ x86mttop 5
+ b 2f
+ x86mttop 6
+ b 2f
+ x86mttop 7
+2:
+ li.w a0, 0 # success
+ jr ra
+SYM_FUNC_END(_restore_ftop_context)
+
+.L_lbt_fault:
+ li.w a0, -EFAULT # failure
+ jr ra