Hexagon: Add hypervisor interface

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 269 insertions, 0 deletions

diff --git a/arch/hexagon/kernel/vm_entry.S b/arch/hexagon/kernel/vm_entry.S
new file mode 100644
index 00000000000..5b99066cbc8
--- /dev/null
+++ b/arch/hexagon/kernel/vm_entry.S
@@ -0,0 +1,269 @@
+/*
+ * Event entry/exit for Hexagon
+ *
+ * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include <asm/asm-offsets.h>  /*  assembly-safer versions of C defines */
+#include <asm/mem-layout.h>   /*  sigh, except for page_offset  */
+#include <asm/hexagon_vm.h>
+#include <asm/thread_info.h>
+
+/*
+ * Entry into guest-mode Linux under Hexagon Virtual Machine.
+ * Stack pointer points to event record - build pt_regs on top of it,
+ * set up a plausible C stack frame, and dispatch to the C handler.
+ * On return, do vmrte virtual instruction with SP where we started.
+ *
+ * VM Spec 0.5 uses a trap to fetch HVM record now.
+ */
+
+/*
+ * Save full register state, while setting up thread_info struct
+ * pointer derived from kernel stack pointer in THREADINFO_REG
+ * register, putting prior thread_info.regs pointer in a callee-save
+ * register (R24, which had better not ever be assigned to THREADINFO_REG),
+ * and updating thread_info.regs to point to current stack frame,
+ * so as to support nested events in kernel mode.
+ *
+ * As this is common code, we set the pt_regs system call number
+ * to -1 for all events.  It will be replaced with the system call
+ * number in the case where we decode a system call (trap0(#1)).
+ */
+
+#define save_pt_regs()\
+	memd(R0 + #_PT_R3130) = R31:30; \
+	{ memw(R0 + #_PT_R2928) = R28; \
+	  R31 = memw(R0 + #_PT_ER_VMPSP); }\
+	{ memw(R0 + #(_PT_R2928 + 4)) = R31; \
+	  R31 = ugp; } \
+	{ memd(R0 + #_PT_R2726) = R27:26; \
+	  R30 = gp ; } \
+	memd(R0 + #_PT_R2524) = R25:24; \
+	memd(R0 + #_PT_R2322) = R23:22; \
+	memd(R0 + #_PT_R2120) = R21:20; \
+	memd(R0 + #_PT_R1918) = R19:18; \
+	memd(R0 + #_PT_R1716) = R17:16; \
+	memd(R0 + #_PT_R1514) = R15:14; \
+	memd(R0 + #_PT_R1312) = R13:12; \
+	{ memd(R0 + #_PT_R1110) = R11:10; \
+	  R15 = lc0; } \
+	{ memd(R0 + #_PT_R0908) = R9:8; \
+	  R14 = sa0; } \
+	{ memd(R0 + #_PT_R0706) = R7:6; \
+	  R13 = lc1; } \
+	{ memd(R0 + #_PT_R0504) = R5:4; \
+	  R12 = sa1; } \
+	{ memd(R0 + #_PT_UGPGP) = R31:30; \
+	  R11 = m1; \
+	  R2.H = #HI(_THREAD_SIZE); } \
+	{ memd(R0 + #_PT_LC0SA0) = R15:14; \
+	  R10 = m0; \
+	  R2.L = #LO(_THREAD_SIZE); } \
+	{ memd(R0 + #_PT_LC1SA1) = R13:12; \
+	  R15 = p3:0; \
+	  R2 = neg(R2); } \
+	{ memd(R0 + #_PT_M1M0) = R11:10; \
+	  R14  = usr; \
+	  R2 = and(R0,R2); } \
+	{ memd(R0 + #_PT_PREDSUSR) =  R15:14; \
+	  THREADINFO_REG = R2; } \
+	{ r24 = memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS); \
+	  memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R0; \
+	  R2 = #-1; } \
+	{ memw(R0 + #_PT_SYSCALL_NR) = R2; \
+	  R30 = #0; }
+
+/*
+ * Restore registers and thread_info.regs state. THREADINFO_REG
+ * is assumed to still be sane, and R24 to have been correctly
+ * preserved. Don't restore R29 (SP) until later.
+ */
+
+#define restore_pt_regs() \
+	{ memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R24; \
+	  R15:14 = memd(R0 + #_PT_PREDSUSR); } \
+	{ R11:10 = memd(R0 + #_PT_M1M0); \
+	  p3:0 = R15; } \
+	{ R13:12 = memd(R0 + #_PT_LC1SA1); \
+	  usr = R14; } \
+	{ R15:14 = memd(R0 + #_PT_LC0SA0); \
+	  m1 = R11; } \
+	{ R3:2 = memd(R0 + #_PT_R0302); \
+	  m0 = R10; } \
+	{ R5:4 = memd(R0 + #_PT_R0504); \
+	  lc1 = R13; } \
+	{ R7:6 = memd(R0 + #_PT_R0706); \
+	  sa1 = R12; } \
+	{ R9:8 = memd(R0 + #_PT_R0908); \
+	  lc0 = R15; } \
+	{ R11:10 = memd(R0 + #_PT_R1110); \
+	  sa0 = R14; } \
+	{ R13:12 = memd(R0 + #_PT_R1312); \
+	  R15:14 = memd(R0 + #_PT_R1514); } \
+	{ R17:16 = memd(R0 + #_PT_R1716); \
+	  R19:18 = memd(R0 + #_PT_R1918); } \
+	{ R21:20 = memd(R0 + #_PT_R2120); \
+	  R23:22 = memd(R0 + #_PT_R2322); } \
+	{ R25:24 = memd(R0 + #_PT_R2524); \
+	  R27:26 = memd(R0 + #_PT_R2726); } \
+	R31:30 = memd(R0 + #_PT_UGPGP); \
+	{ R28 = memw(R0 + #_PT_R2928); \
+	  ugp = R31; } \
+	{ R31:30 = memd(R0 + #_PT_R3130); \
+	  gp = R30; }
+
+	/*
+	 * Clears off enough space for the rest of pt_regs; evrec is a part
+	 * of pt_regs in HVM mode.  Save R0/R1, set handler's address in R1.
+	 * R0 is the address of pt_regs and is the parameter to save_pt_regs.
+	 */
+
+/*
+ * Since the HVM isn't automagically pushing the EVREC onto the stack anymore,
+ * we'll subract the entire size out and then fill it in ourselves.
+ * Need to save off R0, R1, R2, R3 immediately.
+ */
+
+#define	vm_event_entry(CHandler) \
+	{ \
+		R29 = add(R29, #-(_PT_REGS_SIZE)); \
+		memd(R29 + #(_PT_R0100 + -_PT_REGS_SIZE)) = R1:0; \
+	} \
+	{ \
+		memd(R29 +#_PT_R0302) = R3:2; \
+	} \
+	trap1(#HVM_TRAP1_VMGETREGS); \
+	{ \
+		memd(R29 + #_PT_ER_VMEL) = R1:0; \
+		R0 = R29; \
+		R1.L = #LO(CHandler); \
+	} \
+	{ \
+		memd(R29 + #_PT_ER_VMPSP) = R3:2; \
+		R1.H = #HI(CHandler); \
+		jump event_dispatch; \
+	}
+
+.text
+	/*
+	 * Do bulk save/restore in one place.
+	 * Adds a jump to dispatch latency, but
+	 * saves hundreds of bytes.
+	 */
+
+event_dispatch:
+	save_pt_regs()
+	callr	r1
+
+	/*
+	 * If we were in kernel mode, we don't need to check scheduler
+	 * or signals if CONFIG_PREEMPT is not set.  If set, then it has
+	 * to jump to a need_resched kind of block.
+	 * BTW, CONFIG_PREEMPT is not supported yet.
+	 */
+
+#ifdef CONFIG_PREEMPT
+	R0 = #VM_INT_DISABLE
+	trap1(#HVM_TRAP1_VMSETIE)
+#endif
+
+	/*  "Nested control path" -- if the previous mode was kernel  */
+	R0 = memw(R29 + #_PT_ER_VMEST);
+	P0 = tstbit(R0, #HVM_VMEST_UM_SFT);
+	if !P0 jump restore_all;
+	/*
+	 * Returning from system call, normally coming back from user mode
+	 */
+return_from_syscall:
+	/*  Disable interrupts while checking TIF  */
+	R0 = #VM_INT_DISABLE
+	trap1(#HVM_TRAP1_VMSETIE)
+
+	/*
+	 * Coming back from the C-world, our thread info pointer
+	 * should be in the designated register (usually R19)
+	 */
+	R1.L = #LO(_TIF_ALLWORK_MASK)
+	{
+		R1.H = #HI(_TIF_ALLWORK_MASK);
+		R0 = memw(THREADINFO_REG + #_THREAD_INFO_FLAGS);
+	}
+
+	/*
+	 * Compare against the "return to userspace" _TIF_WORK_MASK
+	 */
+	R1 = and(R1,R0);
+	{ P0 = cmp.eq(R1,#0); if (!P0.new) jump:t work_pending;}
+	jump restore_all;  /*  we're outta here!  */
+
+work_pending:
+	{
+		P0 = tstbit(R1, #TIF_NEED_RESCHED);
+		if (!P0.new) jump:nt work_notifysig;
+	}
+	call schedule
+	jump return_from_syscall;  /*  check for more work  */
+
+work_notifysig:
+	/*  this is the part that's kind of fuzzy.  */
+	R1 = and(R0, #(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME));
+	P0 = cmp.eq(R1, #0);
+	if P0 jump restore_all
+	R1 = R0; 	/* unsigned long thread_info_flags */
+	R0 = R29;	/* regs should still be at top of stack  */
+	call do_notify_resume
+
+restore_all:
+	/* Disable interrupts, if they weren't already, before reg restore.  */
+	R0 = #VM_INT_DISABLE
+	trap1(#HVM_TRAP1_VMSETIE)
+
+	/*  do the setregs here for VM 0.5  */
+	/*  R29 here should already be pointing at pt_regs  */
+	R1:0 = memd(R29 + #_PT_ER_VMEL);
+	R3:2 = memd(R29 + #_PT_ER_VMPSP);
+	trap1(#HVM_TRAP1_VMSETREGS);
+
+	R0 = R29
+	restore_pt_regs()
+	R1:0 = memd(R29 + #_PT_R0100);
+	R29 = add(R29, #_PT_REGS_SIZE);
+	trap1(#HVM_TRAP1_VMRTE)
+	/* Notreached */
+
+	.globl _K_enter_genex
+_K_enter_genex:
+	vm_event_entry(do_genex)
+
+	.globl _K_enter_interrupt
+_K_enter_interrupt:
+	vm_event_entry(arch_do_IRQ)
+
+	.globl _K_enter_trap0
+_K_enter_trap0:
+	vm_event_entry(do_trap0)
+
+	.globl _K_enter_machcheck
+_K_enter_machcheck:
+	vm_event_entry(do_machcheck)
+
+
+	.globl ret_from_fork
+ret_from_fork:
+	call schedule_tail
+	jump return_from_syscall