[src/trunk]: src/sys/arch/amd64/amd64 KNF and simplify.

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

details:   https://anonhg.NetBSD.org/src/rev/cfb52ae806c8
branches:  trunk
changeset: 816527:cfb52ae806c8
user:      maxv <maxv%NetBSD.org@localhost>
date:      Mon Jul 11 14:52:54 2016 +0000

description:
KNF and simplify.

diffstat:

 sys/arch/amd64/amd64/locore.S |  77 +++++++++++++++++++++++-------------------
 1 files changed, 42 insertions(+), 35 deletions(-)

diffs (173 lines):

diff -r 294934228838 -r cfb52ae806c8 sys/arch/amd64/amd64/locore.S
--- a/sys/arch/amd64/amd64/locore.S     Mon Jul 11 14:51:11 2016 +0000
+++ b/sys/arch/amd64/amd64/locore.S     Mon Jul 11 14:52:54 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.S,v 1.106 2016/07/09 06:58:06 maxv Exp $        */
+/*     $NetBSD: locore.S,v 1.107 2016/07/11 14:52:54 maxv Exp $        */
 
 /*
  * Copyright-o-rama!
@@ -985,10 +985,9 @@
        movq    %rsi,%rdi
        addq    $USPACE,%rdi
        subq    $KERNBASE,%rdi  /* init_x86_64 wants a physical address */
+#endif /* XEN */
 
-#endif /* XEN */
        call    _C_LABEL(init_x86_64)
-
        call    _C_LABEL(main)
 END(start)
 
@@ -1175,9 +1174,10 @@
 
        /* The 32bit LWPs are handled differently. */
        testl   $PCB_COMPAT32,PCB_FLAGS(%r14)
-       jne     32f
+       jne     lwp_64bit
 
-       /* Zero out %fs/%gs registers and GDT descriptors. */
+lwp_32bit:
+       /* Zero out %fs/%gs registers. */
        xorq    %rax,%rax
        movw    %ax,%fs
        CLI(cx)
@@ -1186,6 +1186,7 @@
        SWAPGS
        STI(cx)
 
+       /* Zero out GDT descriptors. */
        movq    CPUVAR(GDT),%rcx
        movq    %rax,(GUFS_SEL*8)(%rcx)
        movq    %rax,(GUGS_SEL*8)(%rcx)
@@ -1199,9 +1200,10 @@
        movl    PCB_GS(%r14),%eax
        movl    4+PCB_GS(%r14),%edx
        wrmsr
+
        jmp     switch_return
 
-32:
+lwp_64bit:
        /* Reload %fs/%gs GDT descriptors. */
        movq    CPUVAR(GDT),%rcx
        movq    PCB_FS(%r14),%rax
@@ -1259,14 +1261,16 @@
 IDTVEC(syscall)
 #ifndef XEN
        /*
-        * The user %rip is in %rcx and the user %flags in %r11.
-        * The kernel %cs and %ss are loaded, but nothing else is.
-        * The 'swapgs' gives us access to cpu-specific memory where
-        * we can save a user register and then read the lwps
-        * kernel stack pointer,
-        * This code doesn't seem to set %ds, this may not matter since it
-        * is ignored in 64bit mode, OTOH the syscall instruction sets %ss
-        * and that is ignored as well.
+        * The user %rip is in %rcx and the user %flags in %r11. The kernel %cs
+        * and %ss are loaded, but nothing else is.
+        *
+        * The 'swapgs' instruction gives us access to cpu-specific memory where
+        * we can save a user register and then read the LWP's kernel stack
+        * pointer.
+        *
+        * This code doesn't seem to set %ds, this may not matter since it is
+        * ignored in 64bit mode, OTOH the syscall instruction sets %ss and that
+        * is ignored as well.
         */
        swapgs
        movq    %r15,CPUVAR(SCRATCH)
@@ -1276,19 +1280,19 @@
 
        /* Make stack look like an 'int nn' frame */
 #define SP(x)  (x)-(TF_SS+8)(%r15)
-       movq    $(LSEL(LUDATA_SEL, SEL_UPL)), SP(TF_SS) /* user %ss */
-       movq    %rsp, SP(TF_RSP)        /* User space rsp */
+       movq    $(LSEL(LUDATA_SEL, SEL_UPL)),SP(TF_SS) /* user %ss */
+       movq    %rsp,SP(TF_RSP)         /* User space rsp */
 
-       movq    %r11, SP(TF_RFLAGS)     /* old rflags from syscall insn */
-       movq    $(LSEL(LUCODE_SEL, SEL_UPL)), SP(TF_CS)
-       movq    %rcx, SP(TF_RIP)        /* syscall saves rip in rcx */
+       movq    %r11,SP(TF_RFLAGS)      /* old rflags from syscall insn */
+       movq    $(LSEL(LUCODE_SEL, SEL_UPL)),SP(TF_CS)
+       movq    %rcx,SP(TF_RIP)         /* syscall saves rip in rcx */
 
        leaq    SP(0),%rsp              /* %rsp now valid after frame */
        movq    CPUVAR(SCRATCH),%r15
 #undef SP
 
        movq    $2,TF_ERR(%rsp)         /* syscall instruction size */
-       movq    $T_ASTFLT, TF_TRAPNO(%rsp)
+       movq    $T_ASTFLT,TF_TRAPNO(%rsp)
 
        movw    %es,TF_ES(%rsp)
        sti
@@ -1328,27 +1332,29 @@
         */
        CLI(si)
        /* Check for ASTs on exit to user mode. */
-       movl    L_MD_ASTPENDING(%r14), %eax
-       orl     CPUVAR(WANT_PMAPLOAD), %eax
+       movl    L_MD_ASTPENDING(%r14),%eax
+       orl     CPUVAR(WANT_PMAPLOAD),%eax
        jnz     9f
+
 #ifdef DIAGNOSTIC
        cmpl    $IPL_NONE,CPUVAR(ILEVEL)
-       jne     3f
+       jne     spl_error
 #endif
-       testl   $(MDL_IRET | MDL_COMPAT32), L_MD_FLAGS(%r14)
+
+       testl   $(MDL_IRET|MDL_COMPAT32),L_MD_FLAGS(%r14)
        INTR_RESTORE_GPRS
        movw    TF_ES(%rsp),%es
        SWAPGS
        jnz     2f
 #ifndef XEN
-       movq    TF_RIP(%rsp), %rcx      /* %rip for sysret */
-       movq    TF_RFLAGS(%rsp), %r11   /* %flags for sysret */
-       movw    TF_DS(%rsp), %ds
-       movq    TF_RSP(%rsp), %rsp
+       movq    TF_RIP(%rsp),%rcx       /* %rip for sysret */
+       movq    TF_RFLAGS(%rsp),%r11    /* %flags for sysret */
+       movw    TF_DS(%rsp),%ds
+       movq    TF_RSP(%rsp),%rsp
        sysretq
 #else
-       movw    TF_DS(%rsp), %ds
-       addq    $TF_RIP, %rsp
+       movw    TF_DS(%rsp),%ds
+       addq    $TF_RIP,%rsp
        pushq   $256    /* VGCF_IN_SYSCALL */
        jmp     HYPERVISOR_iret
 #endif
@@ -1360,13 +1366,14 @@
  * then a SIGSEGV will be signalled.
  */
 2:
-       movw    TF_DS(%rsp), %ds
-       addq    $TF_RIP, %rsp
+       movw    TF_DS(%rsp),%ds
+       addq    $TF_RIP,%rsp
        iretq
 
-/* Report SPL error */
 #ifdef DIAGNOSTIC
-3:     movabsq $4f, %rdi
+       /* Report SPL error */
+spl_error:
+       movabsq $4f,%rdi
        movl    TF_RAX(%rsp),%esi
        movl    TF_RDI(%rsp),%edx
        movl    %ebx,%ecx
@@ -1381,7 +1388,7 @@
 
 /* AST pending or pmap load needed */
 9:
-       cmpl    $0, CPUVAR(WANT_PMAPLOAD)
+       cmpl    $0,CPUVAR(WANT_PMAPLOAD)
        jz      10f
        STI(si)
        call    _C_LABEL(do_pmap_load)