Accessing memory beyond 1GB (with or w/o PAE) requires 2 memory
zones.
-if ISA_ARCOMPACT
-
config ARC_COMPACT_IRQ_LEVELS
+ depends on ISA_ARCOMPACT
bool "Setup Timer IRQ as high Priority"
# if SMP, LV2 enabled ONLY if ARC implementation has LV2 re-entrancy
depends on !SMP
config ARC_FPU_SAVE_RESTORE
bool "Enable FPU state persistence across context switch"
help
- Double Precision Floating Point unit had dedicated regs which
- need to be saved/restored across context-switch.
- Note that ARC FPU is overly simplistic, unlike say x86, which has
- hardware pieces to allow software to conditionally save/restore,
- based on actual usage of FPU by a task. Thus our implemn does
- this for all tasks in system.
-
-endif #ISA_ARCOMPACT
+ ARCompact FPU has internal registers to assist with Double precision
+ Floating Point operations. There are control and stauts registers
+ for floating point exceptions and rounding modes. These are
+ preserved across task context switch when enabled.
config ARC_CANT_LLSC
def_bool n
#define ARC_REG_CLUSTER_BCR 0xcf
#define ARC_REG_AUX_ICCM 0x208 /* ICCM Base Addr (ARCv2) */
#define ARC_REG_LPB_CTRL 0x488 /* ARCv2 Loop Buffer control */
+#define ARC_REG_FPU_CTRL 0x300
+#define ARC_REG_FPU_STATUS 0x301
/* Common for ARCompact and ARCv2 status register */
#define ARC_REG_STATUS32 0x0A
#include <asm/ptrace.h>
+#ifdef CONFIG_ISA_ARCOMPACT
+
/* These DPFP regs need to be saved/restored across ctx-sw */
struct arc_fpu {
struct {
} aux_dpfp[2];
};
-extern void fpu_save_restore(struct task_struct *p, struct task_struct *n);
+#define fpu_init_task(regs)
#else
+/*
+ * ARCv2 FPU Control aux register
+ * - bits to enable Traps on Exceptions
+ * - Rounding mode
+ *
+ * ARCv2 FPU Status aux register
+ * - FPU exceptions flags (Inv, Div-by-Zero, overflow, underflow, inexact)
+ * - Flag Write Enable to clear flags explicitly (vs. by fpu instructions
+ * only
+ */
+
+struct arc_fpu {
+ unsigned int ctrl, status;
+};
+
+extern void fpu_init_task(struct pt_regs *regs);
+
+#endif /* !CONFIG_ISA_ARCOMPACT */
+
+extern void fpu_save_restore(struct task_struct *p, struct task_struct *n);
+
+#else /* !CONFIG_ARC_FPU_SAVE_RESTORE */
+
#define fpu_save_restore(p, n)
+#define fpu_init_task(regs)
#endif /* CONFIG_ARC_FPU_SAVE_RESTORE */
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
obj-$(CONFIG_ARC_FPU_SAVE_RESTORE) += fpu.o
+ifdef CONFIG_ISA_ARCOMPACT
CFLAGS_fpu.o += -mdpfp
+endif
ifdef CONFIG_ARC_DW2_UNWIND
CFLAGS_ctx_sw.o += -fno-omit-frame-pointer
#include <linux/sched.h>
#include <asm/fpu.h>
+#ifdef CONFIG_ISA_ARCOMPACT
+
/*
* To save/restore FPU regs, simplest scheme would use LR/SR insns.
* However since SR serializes the pipeline, an alternate "hack" can be used
: "r" (zero), "r" (*(readfrom + 3)), "r" (*(readfrom + 2))
);
}
+
+#else
+
+void fpu_init_task(struct pt_regs *regs)
+{
+ /* default rounding mode */
+ write_aux_reg(ARC_REG_FPU_CTRL, 0x100);
+
+ /* set "Write enable" to allow explicit write to exception flags */
+ write_aux_reg(ARC_REG_FPU_STATUS, 0x80000000);
+}
+
+void fpu_save_restore(struct task_struct *prev, struct task_struct *next)
+{
+ struct arc_fpu *save = &prev->thread.fpu;
+ struct arc_fpu *restore = &next->thread.fpu;
+
+ save->ctrl = read_aux_reg(ARC_REG_FPU_CTRL);
+ save->status = read_aux_reg(ARC_REG_FPU_STATUS);
+
+ write_aux_reg(ARC_REG_FPU_CTRL, restore->ctrl);
+ write_aux_reg(ARC_REG_FPU_STATUS, restore->status);
+}
+
+#endif
#include <linux/elf.h>
#include <linux/tick.h>
+#include <asm/fpu.h>
+
SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
{
task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
/*
* Do necessary setup to start up a new user task
*/
-void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp)
+void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
{
regs->sp = usp;
regs->ret = pc;
regs->eflags = 0;
#endif
+ fpu_init_task(regs);
+
/* bogus seed values for debugging */
regs->lp_start = 0x10;
regs->lp_end = 0x80;