Changes in kernel/arch/amd64/src/asm.S [1a5eca4:3b0f1b9a] in mainline

File:

• kernel/arch/amd64/src/asm.S (modified) (6 diffs)

kernel/arch/amd64/src/asm.S

@@ -31 +31 @@
 #include <arch/mm/page.h>
 #include <arch/istate_struct.h>
-#include <arch/kseg_struct.h>
-#include <arch/cpu.h>
 
 .text
@@ -180 +178 @@
                 subq $(ISTATE_SOFT_SIZE + 8), %rsp
         .endif
-
+        
         /*
          * Save the general purpose registers.
@@ -201 +199 @@
 
         /*
-         * Is this trap from the kernel?
-         */
-        cmpq $(GDT_SELECTOR(KTEXT_DES)), ISTATE_OFFSET_CS(%rsp)
-        jz 0f
-
-        /*
-         * Switch to kernel FS base.
-         */
-        swapgs
-        movl $AMD_MSR_FS, %ecx
-        movl %gs:KSEG_OFFSET_FSBASE, %eax
-        movl %gs:KSEG_OFFSET_FSBASE+4, %edx
-        wrmsr
-        swapgs
-
-        /*
          * Imitate a regular stack frame linkage.
          * Stop stack traces here if we came from userspace.
          */
-0:      movl $0x0, %edx
+        xorl %edx, %edx
+        cmpq $(GDT_SELECTOR(KTEXT_DES)), ISTATE_OFFSET_CS(%rsp)
         cmovnzq %rdx, %rbp
 
@@ -289 +272 @@
         swapgs
         
-        movq %rsp, %gs:KSEG_OFFSET_USTACK_RSP  /* save this thread's user RSP */
-        movq %gs:KSEG_OFFSET_KSTACK_RSP, %rsp  /* set this thread's kernel RSP */
-
+        /*
+         * %gs:0 Scratch space for this thread's user RSP
+         * %gs:8 Address to be used as this thread's kernel RSP
+         */
+        
+        movq %rsp, %gs:0  /* save this thread's user RSP */
+        movq %gs:8, %rsp  /* set this thread's kernel RSP */
+        
         /*
          * Note that the space needed for the imitated istate structure has been
@@ -320 +308 @@
 
         /*
-         * Switch to kernel FS base.
-         */
-        movl $AMD_MSR_FS, %ecx
-        movl %gs:KSEG_OFFSET_FSBASE, %eax
-        movl %gs:KSEG_OFFSET_FSBASE+4, %edx
-        wrmsr
-        movq ISTATE_OFFSET_RDX(%rsp), %rdx      /* restore 3rd argument */
-
-        /*
          * Save the return address and the userspace stack on locations that
          * would normally be taken by them.
          */
-        movq %gs:KSEG_OFFSET_USTACK_RSP, %rax
+        movq %gs:0, %rax
         movq %rax, ISTATE_OFFSET_RSP(%rsp)
         movq %rcx, ISTATE_OFFSET_RIP(%rsp)
@@ -346 +325 @@
         swapgs
         sti
-
+        
         /* Copy the 4th argument where it is expected  */
         movq %r10, %rcx