[src/trunk]: src/sys/arch/riscv Optimize the exception handle a little bit more.

[matt <matt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b152df7a30e3
branches:  trunk
changeset: 337046:b152df7a30e3
user:      matt <matt%NetBSD.org@localhost>
date:      Tue Mar 31 06:47:47 2015 +0000

description:
Optimize the exception handle a little bit more.

diffstat:

 sys/arch/riscv/include/proc.h    |   4 ++--
 sys/arch/riscv/riscv/genassym.cf |   4 ++--
 sys/arch/riscv/riscv/locore.S    |  30 +++++++++++++++++-------------
 3 files changed, 21 insertions(+), 17 deletions(-)

diffs (138 lines):

diff -r 0b546366f8eb -r b152df7a30e3 sys/arch/riscv/include/proc.h
--- a/sys/arch/riscv/include/proc.h     Tue Mar 31 01:36:27 2015 +0000
+++ b/sys/arch/riscv/include/proc.h     Tue Mar 31 06:47:47 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: proc.h,v 1.2 2015/03/31 01:12:29 matt Exp $    */
+/*     $NetBSD: proc.h,v 1.3 2015/03/31 06:47:47 matt Exp $    */
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -46,7 +46,7 @@
        struct trapframe *md_utf;       /* trapframe from userspace */
        struct trapframe *md_ktf;       /* trapframe from userspace */
        struct faultbuf *md_onfault;    /* registers to store on fault */
-       register_t md_tp;               /* for locore.S */
+       register_t md_usp;              /* for locore.S */
        vaddr_t md_ss_addr;             /* single step address for ptrace */
        int     md_ss_instr;            /* single step instruction for ptrace */
        volatile int md_astpending;     /* AST pending on return to userland */
diff -r 0b546366f8eb -r b152df7a30e3 sys/arch/riscv/riscv/genassym.cf
--- a/sys/arch/riscv/riscv/genassym.cf  Tue Mar 31 01:36:27 2015 +0000
+++ b/sys/arch/riscv/riscv/genassym.cf  Tue Mar 31 06:47:47 2015 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: genassym.cf,v 1.2 2015/03/31 01:12:47 matt Exp $
+#      $NetBSD: genassym.cf,v 1.3 2015/03/31 06:47:47 matt Exp $
 #-
 # Copyright (c) 2014 The NetBSD Foundation, Inc.
 # All rights reserved.
@@ -114,7 +114,7 @@
 define L_CTXSWTCH      offsetof(struct lwp, l_ctxswtch)
 define L_MD_ASTPENDING offsetof(struct lwp, l_md.md_astpending)
 define L_MD_ONFAULT    offsetof(struct lwp, l_md.md_onfault)
-define L_MD_TP         offsetof(struct lwp, l_md.md_tp)
+define L_MD_USP        offsetof(struct lwp, l_md.md_usp)
 define L_MD_UTF        offsetof(struct lwp, l_md.md_utf)
 define L_MD_KTF        offsetof(struct lwp, l_md.md_ktf)
 define L_PCB           offsetof(struct lwp, l_addr)
diff -r 0b546366f8eb -r b152df7a30e3 sys/arch/riscv/riscv/locore.S
--- a/sys/arch/riscv/riscv/locore.S     Tue Mar 31 01:36:27 2015 +0000
+++ b/sys/arch/riscv/riscv/locore.S     Tue Mar 31 06:47:47 2015 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.2 2015/03/31 01:30:50 matt Exp $ */
+/* $NetBSD: locore.S,v 1.3 2015/03/31 06:47:47 matt Exp $ */
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
  * All rights reserved.
@@ -306,8 +306,8 @@
 // RISCV only has a simple exception handler handles both synchronous traps
 // and interrupts.
 ENTRY_NP(cpu_exception_handler)
-       csrrw   sp, sscratch, sp        // swap scratch and stack pointer
-       beqz    sp, .Lexception_kernel  //   sp == 0, already on kernel stack
+       csrrw   tp, sscratch, tp        // swap scratch and thread pointer
+       beqz    tp, .Lexception_kernel  //   tp == 0, already on kernel stack
        //
        // The execption happened while user code was executing.  We need to
        // get the pointer to the user trapframe from the LWP md area.  Then we
@@ -315,14 +315,14 @@
        // into tp.  We also save the saved SP into the trapframe.
        // Upon entry on an exception from user, sscratch will contain curlwp.
        //
-       REG_S   tp, L_MD_TP(sp)         // save thread pointer temporarily
-       mv      tp, sp                  // put curlwp in thread pointer
+       REG_S   sp, L_MD_USP(tp)        // save user stack pointer temporarily
        PTR_L   sp, L_MD_UTF(sp)        // trapframe pointer loaded
        REG_S   t1, TF_T1(sp)           // save t1
-       csrrw   t1, sscratch, zero      // save saved stack pointer with 0
-       REG_S   t1, TF_SP(sp)           // save stack pointer
-       REG_S   t1, L_MD_TP(tp)         // get thread pointer from temp store
+       REG_S   t1, L_MD_USP(tp)        // get user stack pointer
        REG_L   t1, TF_SP(sp)           // save thread pointer in trapframe
+       csrrw   t1, sscratch, zero      // swap saved thread pointer with 0
+       REG_L   t1, TF_TP(sp)           // save thread pointer in trapframe
+       li      t1, 0                   // indicate user exception
        j       .Lexception_common
 
        //
@@ -333,11 +333,13 @@
        // trapframe for use by the exception exiting code.
        //
 .Lexception_kernel:
-       csrrw   sp, sscratch, zero      // get back our stack pointer
+       csrrw   tp, sscratch, zero      // get back our thread pointer
        addi    sp, sp, -TF_LEN         // allocate stack frame
        REG_S   t1, TF_T1(sp)           // save t1
        addi    t1, sp, TF_LEN
        REG_S   t1, TF_SP(sp)           // save SP
+       li      t1, 1                   // indicate kernel exception
+
 .Lexception_common:
        // Now we save all the temporary registers into the trapframe since
        // they will most certainly be changed.
@@ -364,18 +366,19 @@
        csrr    a1, sepc                // get execption pc
        csrr    a2, sstatus             // get status
        csrr    a3, scause              // get cause
-       csrr    a4, sbadaddr            // get badaddr
 
        REG_S   a1, TF_PC(sp)
        INT_S   a2, TF_SR(sp)
        INT_S   a3, TF_CAUSE(sp)        // save cause
-       REG_S   a4, TF_BADADDR(sp)
 
        // Now we've saved the trapfame, the cause is still in a3.
 
-       andi    t1, a2, SR_PS           // t1 == user or kernel flag
        bltz    a3, intr_handler        // MSB is set if interrupt
 
+       // badaddr is only relavent for non-interrupts
+       csrr    a4, sbadaddr            // get badaddr
+       REG_S   a4, TF_BADADDR(sp)
+
        beqz    t1, trap_user           // this was a user trap
        // This was a kernel exception
        call    _C_LABEL(cpu_trap)      // just call trap to handle it
@@ -438,6 +441,7 @@
        bnez    t0, trap_doast          //   yes, handle it.
        csrrci  zero, sstatus, SR_EI    // disable interrupts
        csrw    sscratch, tp            // show we are coming from userland
+       REG_L   tp, TF_TP(sp)           // only restore from userland
        REG_L   s0, TF_S0(sp)           // only restore from userland
        REG_L   s1, TF_S1(sp)           // only restore from userland
        REG_L   s2, TF_S2(sp)           // only restore from userland
@@ -450,7 +454,6 @@
        REG_L   s9, TF_S9(sp)           // only restore from userland
        REG_L   s10, TF_S10(sp)         // only restore from userland
        REG_L   s11, TF_S11(sp)         // only restore from userland
-       REG_L   tp, TF_TP(sp)           // only restore from userland
        j       exception_kernexit
 
 trap_syscall:
@@ -482,6 +485,7 @@
        INT_L   t0, L_MD_ASTPENDING(tp) // get astpending
        bnez    t0, intr_usersave       //    if one is pending, deal with in
 
+       csrw    sscratch, tp            // show we are coming from userland
        REG_L   tp, TF_TP(sp)           // restore thread pointer
        j       exception_kernexit      // do standard exception exit