Changeset 37b451f7 in mainline

Timestamp:

2006-02-07T02:22:44Z (19 years ago)

Author:

Ondrej Palkovsky <ondrap@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

65640fef

Parents:

dd4d6b0

Message:

Added (finally!) userspace to AMD64.
It does not work on Simics *$U&%&$&*#. Broken simics!!!
There should be probably LEA instead of MOV/ADD, but LEA does not
work in neither qemu nor bochs. Any other simulator to test? :-/

Location:

arch/amd64

Files:

• include/asm.h (modified) (1 diff)
• include/cpu.h (modified) (1 diff)
• src/asm_utils.S (modified) (1 diff)
• src/proc/scheduler.c (modified) (1 diff)
• src/syscall.c (modified) (3 diffs)

arch/amd64/include/asm.h

@@ -73 +73 @@
 static inline void outb(__u16 port, __u8 val) { __asm__ volatile ("outb %b0, %w1\n" : : "a" (val), "d" (port) ); }
 
+/** Swap Hidden part of GS register with visible one */
+static inline void swapgs(void) { __asm__ volatile("swapgs"); }
+
 /** Enable interrupts.
  *

arch/amd64/include/cpu.h

@@ -42 +42 @@
 #define AMD_MSR_LSTAR   0xc0000082
 #define AMD_MSR_SFMASK  0xc0000084
+#define AMD_MSR_GS      0xc0000101
 
 #ifndef __ASM__

arch/amd64/src/asm_utils.S

@@ -193 +193 @@
         
 syscall_entry:
-        # TODO: Switch to kernel stack
+        # Switch to hidden gs   
+        swapgs
+
+        # TODO: I would like LEA instead of thes 2 instrs,
+        # why does not it work???
+        mov %gs:0, %r10     # We have a stack in r10
+        addq $0x0ff0, %r10
+        
+        movq %rsp, 0(%r10)  # Save old stack pointer to stack
+        movq %r10, %rsp     # Change to new stack
+        pushq %rcx          # Return address
+        pushq %r11          # Save flags
+
+        # Switch back to remain consistent
+        swapgs 
+
+        movq %r9, %rcx      # Exchange last parameter as a third
         call syscall_handler
-        # Switch back
-        sysret
+        
+        popq %r11
+        popq %rcx
+        movq 0(%rsp), %rsp
+        sysretq
                 
 .data

arch/amd64/src/proc/scheduler.c

@@ -32 +32 @@
 #include <arch.h>
 #include <arch/context.h>       /* SP_DELTA */
+#include <arch/asm.h>
 
 void before_thread_runs_arch(void)
 {
         CPU->arch.tss->rsp0 = (__address) &THREAD->kstack[THREAD_STACK_SIZE-SP_DELTA];
+
+        /* Syscall support - write thread address to hidden part of gs */
+        swapgs();
+        write_msr(AMD_MSR_GS,
+                  (__u64)&THREAD->kstack);
+        swapgs();
 }

arch/amd64/src/syscall.c

@@ -35 +35 @@
 
 #include <print.h>
+#include <arch/cpu.h>
 
 extern void syscall_entry(void);
@@ -55 +56 @@
         write_msr(AMD_MSR_LSTAR, (__u64)syscall_entry);
         /* Mask RFLAGS on syscall 
-         * - we do not care what is in the flags field
+         * - disable interrupts, until we exchange the stack register
+         *   (mask the IE bit)
          */
-        write_msr(AMD_MSR_SFMASK, 0);
+        write_msr(AMD_MSR_SFMASK, 0x200);
 }
 
@@ -63 +65 @@
 __native syscall_handler(__native id, __native a1, __native a2, __native a3)
 {
+        interrupts_enable();
         if (id < SYSCALL_END)
                 return syscall_table[id](a1,a2,a3);
         else
                 panic("Undefined syscall %d", id);
-        
+        interrupts_disable();
 }