Module Name: src
Committed By: maxv
Date: Fri Jul 1 13:11:21 UTC 2016
Modified Files:
src/sys/arch/amd64/amd64: locore.S
src/sys/arch/i386/i386: locore.S
Log Message:
Try to make this part more readable. No functional change.
To generate a diff of this commit:
cvs rdiff -u -r1.102 -r1.103 src/sys/arch/amd64/amd64/locore.S
cvs rdiff -u -r1.131 -r1.132 src/sys/arch/i386/i386/locore.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/amd64/amd64/locore.S
diff -u src/sys/arch/amd64/amd64/locore.S:1.102 src/sys/arch/amd64/amd64/locore.S:1.103
--- src/sys/arch/amd64/amd64/locore.S:1.102 Sat Jun 4 10:48:11 2016
+++ src/sys/arch/amd64/amd64/locore.S Fri Jul 1 13:11:21 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.102 2016/06/04 10:48:11 maxv Exp $ */
+/* $NetBSD: locore.S,v 1.103 2016/07/01 13:11:21 maxv Exp $ */
/*
* Copyright-o-rama!
@@ -1072,7 +1072,7 @@ END(dumpsys)
/*
* struct lwp *cpu_switchto(struct lwp *oldlwp, struct lwp *newlwp,
- * bool returning)
+ * bool returning)
*
* 1. if (oldlwp != NULL), save its context.
* 2. then, restore context of newlwp.
@@ -1091,18 +1091,19 @@ ENTRY(cpu_switchto)
movq %rdi,%r13 /* oldlwp */
movq %rsi,%r12 /* newlwp */
- testq %r13,%r13
- jz 1f
+ testq %r13,%r13 /* oldlwp = NULL ? */
+ jz skip_save
/* Save old context. */
movq L_PCB(%r13),%rax
movq %rsp,PCB_RSP(%rax)
movq %rbp,PCB_RBP(%rax)
+skip_save:
/* Switch to newlwp's stack. */
-1: movq L_PCB(%r12),%r14
+ movq L_PCB(%r12),%r14
#ifdef XEN /* XXX debug code */
- cmpq $0, PCB_RSP(%r14)
+ cmpq $0,PCB_RSP(%r14)
jne 999f
callq _C_LABEL(cpu_Debugger);
999:
@@ -1118,21 +1119,21 @@ ENTRY(cpu_switchto)
xchgq %rcx,CPUVAR(CURLWP)
/* Skip the rest if returning to a pinned LWP. */
- testb %dl,%dl
- jnz 4f
+ testb %dl,%dl /* returning = true ? */
+ jnz switch_return
/* Switch ring0 stack */
#ifndef XEN
movq PCB_RSP0(%r14),%rax
movq %rax,CPUVAR(RSP0)
#else
- movq %r14, %rdi
+ movq %r14,%rdi
callq _C_LABEL(x86_64_switch_context);
#endif
/* Don't bother with the rest if switching to a system process. */
testl $LW_SYSTEM,L_FLAG(%r12)
- jnz 4f
+ jnz switch_return
/* Is this process using RAS (restartable atomic sequences)? */
movq L_PROC(%r12),%rdi
@@ -1154,65 +1155,68 @@ ENTRY(cpu_switchto)
* set CR0_TS so we'll trap rather than reuse bogus state.
*/
cmpq CPUVAR(FPCURLWP),%r12
- je 3f
+ je skip_TS
orq $CR0_TS,%rcx
+skip_TS:
/* Reloading CR0 is very expensive - avoid if possible. */
-3: cmpq %rdx,%rcx
- je 6f
+ cmpq %rdx,%rcx
+ je skip_CR0
movq %rcx,%cr0
+skip_CR0:
-6: testl $PCB_COMPAT32, PCB_FLAGS(%r14)
+ /* The 32bit LWPs are handled differently. */
+ testl $PCB_COMPAT32,PCB_FLAGS(%r14)
jne 32f
/* Zero out %fs/%gs registers and GDT descriptors. */
- xorq %rax, %rax
- movw %ax, %fs
+ xorq %rax,%rax
+ movw %ax,%fs
CLI(cx)
SWAPGS
- movw %ax, %gs
+ movw %ax,%gs
SWAPGS
STI(cx)
movq CPUVAR(GDT),%rcx
- movq %rax, (GUFS_SEL*8)(%rcx)
- movq %rax, (GUGS_SEL*8)(%rcx)
+ movq %rax,(GUFS_SEL*8)(%rcx)
+ movq %rax,(GUGS_SEL*8)(%rcx)
/* Reload 64-bit %fs/%gs MSRs. */
- movl $MSR_FSBASE, %ecx
- movl PCB_FS(%r14), %eax
- movl 4+PCB_FS(%r14), %edx
+ movl $MSR_FSBASE,%ecx
+ movl PCB_FS(%r14),%eax
+ movl 4+PCB_FS(%r14),%edx
wrmsr
- movl $MSR_KERNELGSBASE, %ecx
- movl PCB_GS(%r14), %eax
- movl 4+PCB_GS(%r14), %edx
+ movl $MSR_KERNELGSBASE,%ecx
+ movl PCB_GS(%r14),%eax
+ movl 4+PCB_GS(%r14),%edx
wrmsr
- jmp 4f
+ jmp switch_return
32:
/* Reload %fs/%gs GDT descriptors. */
movq CPUVAR(GDT),%rcx
- movq PCB_FS(%r14), %rax
- movq %rax, (GUFS_SEL*8)(%rcx)
- movq PCB_GS(%r14), %rax
- movq %rax, (GUGS_SEL*8)(%rcx)
+ movq PCB_FS(%r14),%rax
+ movq %rax,(GUFS_SEL*8)(%rcx)
+ movq PCB_GS(%r14),%rax
+ movq %rax,(GUGS_SEL*8)(%rcx)
/* Reload %fs and %gs */
- movq L_MD_REGS(%r12), %rbx
- movw TF_FS(%rbx), %fs
+ movq L_MD_REGS(%r12),%rbx
+ movw TF_FS(%rbx),%fs
CLI(ax)
SWAPGS
- movw TF_GS(%rbx), %gs
+ movw TF_GS(%rbx),%gs
SWAPGS
STI(ax)
-
#else
movq %r12,%rdi
callq _C_LABEL(x86_64_tls_switch)
#endif
+switch_return:
/* Return to the new LWP, returning 'oldlwp' in %rax. */
-4: movq %r13,%rax
+ movq %r13,%rax
popq %r15
popq %r14
popq %r13
Index: src/sys/arch/i386/i386/locore.S
diff -u src/sys/arch/i386/i386/locore.S:1.131 src/sys/arch/i386/i386/locore.S:1.132
--- src/sys/arch/i386/i386/locore.S:1.131 Sat Jun 4 10:48:11 2016
+++ src/sys/arch/i386/i386/locore.S Fri Jul 1 13:11:21 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.131 2016/06/04 10:48:11 maxv Exp $ */
+/* $NetBSD: locore.S,v 1.132 2016/07/01 13:11:21 maxv Exp $ */
/*
* Copyright-o-rama!
@@ -128,7 +128,7 @@
*/
#include <machine/asm.h>
-__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.131 2016/06/04 10:48:11 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.132 2016/07/01 13:11:21 maxv Exp $");
#include "opt_compat_oldboot.h"
#include "opt_copy_symtab.h"
@@ -1100,7 +1100,7 @@ END(dumpsys)
/*
* struct lwp *cpu_switchto(struct lwp *oldlwp, struct lwp *newlwp,
- * bool returning)
+ * bool returning)
*
* 1. if (oldlwp != NULL), save its context.
* 2. then, restore context of newlwp.
@@ -1128,16 +1128,18 @@ ENTRY(cpu_switchto)
movl 16(%esp),%esi /* oldlwp */
movl 20(%esp),%edi /* newlwp */
movl 24(%esp),%edx /* returning */
- testl %esi,%esi
- jz 1f
+
+ testl %esi,%esi /* oldlwp = NULL ? */
+ jz skip_save
/* Save old context. */
movl L_PCB(%esi),%eax
movl %esp,PCB_ESP(%eax)
movl %ebp,PCB_EBP(%eax)
+skip_save:
/* Switch to newlwp's stack. */
-1: movl L_PCB(%edi),%ebx
+ movl L_PCB(%edi),%ebx
movl PCB_EBP(%ebx),%ebp
movl PCB_ESP(%ebx),%esp
@@ -1150,33 +1152,33 @@ ENTRY(cpu_switchto)
/* Skip the rest if returning to a pinned LWP. */
testl %edx,%edx
- jnz 4f
+ jnz switch_return
+ /* Switch ring0 stack */
#ifdef XEN
pushl %edi
call _C_LABEL(i386_switch_context)
addl $4,%esp
-#else /* !XEN */
- /* Switch ring0 esp */
+#else
movl PCB_ESP0(%ebx),%eax
movl %eax,CPUVAR(ESP0)
-#endif /* !XEN */
+#endif
/* Don't bother with the rest if switching to a system process. */
testl $LW_SYSTEM,L_FLAG(%edi)
- jnz 4f
+ jnz switch_return
#ifndef XEN
/* Restore thread-private %fs/%gs descriptors. */
movl CPUVAR(GDT),%ecx
- movl PCB_FSD(%ebx), %eax
- movl PCB_FSD+4(%ebx), %edx
- movl %eax, (GUFS_SEL*8)(%ecx)
- movl %edx, (GUFS_SEL*8+4)(%ecx)
- movl PCB_GSD(%ebx), %eax
- movl PCB_GSD+4(%ebx), %edx
- movl %eax, (GUGS_SEL*8)(%ecx)
- movl %edx, (GUGS_SEL*8+4)(%ecx)
+ movl PCB_FSD(%ebx),%eax
+ movl PCB_FSD+4(%ebx),%edx
+ movl %eax,(GUFS_SEL*8)(%ecx)
+ movl %edx,(GUFS_SEL*8+4)(%ecx)
+ movl PCB_GSD(%ebx),%eax
+ movl PCB_GSD+4(%ebx),%edx
+ movl %eax,(GUGS_SEL*8)(%ecx)
+ movl %edx,(GUGS_SEL*8+4)(%ecx)
#endif /* !XEN */
/* Switch I/O bitmap */
@@ -1211,17 +1213,19 @@ ENTRY(cpu_switchto)
* set CR0_TS so we'll trap rather than reuse bogus state.
*/
cmpl CPUVAR(FPCURLWP),%edi
- je 3f
+ je skip_TS
orl $CR0_TS,%ecx
+skip_TS:
/* Reloading CR0 is very expensive - avoid if possible. */
-3: cmpl %edx,%ecx
- je 4f
+ cmpl %edx,%ecx
+ je switch_return
movl %ecx,%cr0
#endif /* !XEN */
+switch_return:
/* Return to the new LWP, returning 'oldlwp' in %eax. */
-4: movl %esi,%eax
+ movl %esi,%eax
popl %edi
popl %esi
popl %ebx
