Changeset f2ef7fd in mainline for kernel

Timestamp:

2008-10-05T21:20:13Z (17 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

6198611

Parents:

1d132ae

Message:

Support for SYSENTER on ia32.

Location:

kernel/arch

Files:

• amd64/include/syscall.h (modified) (1 diff)
• ia32/Makefile.inc (modified) (1 diff)
• ia32/include/asm.h (modified) (1 diff)
• ia32/include/cpu.h (modified) (2 diffs)
• ia32/include/syscall.h (added)
• ia32/src/asm.S (modified) (1 diff)
• ia32/src/cpu/cpu.c (modified) (2 diffs)
• ia32/src/proc/scheduler.c (modified) (1 diff)
• ia32/src/syscall.c (added)

kernel/arch/amd64/include/syscall.h

@@ -36 +36 @@
 #define KERN_amd64_SYSCALL_H_
 
-#include <arch/types.h>
-
 extern void syscall_setup_cpu(void);
 

kernel/arch/ia32/Makefile.inc

@@ -161 +161 @@
         arch/$(ARCH)/src/boot/memmap.c \
         arch/$(ARCH)/src/fpu_context.c \
-        arch/$(ARCH)/src/debugger.c
+        arch/$(ARCH)/src/debugger.c \
+        arch/$(ARCH)/src/syscall.c

kernel/arch/ia32/include/asm.h

@@ -248 +248 @@
 }
 
+/** Write to MSR */
+static inline void write_msr(uint32_t msr, uint64_t value)
+{
+        asm volatile ("wrmsr" : : "c" (msr), "a" ((uint32_t)(value)),
+            "d" ((uint32_t)(value >> 32)));
+}
+
+static inline uint64_t read_msr(uint32_t msr)
+{
+        uint32_t ax, dx;
+
+        asm volatile ("rdmsr" : "=a"(ax), "=d"(dx) : "c" (msr));
+        return ((uint64_t)dx << 32) | ax;
+}
+
+
 /** Return base address of current stack
  *

kernel/arch/ia32/include/cpu.h

@@ -36 +36 @@
 #define KERN_ia32_CPU_H_
 
+#define EFLAGS_IF       (1 << 9)
+#define EFLAGS_RF       (1 << 16)
+
+#define CR4_OSFXSR_MASK (1<<9)
+
+/* Support for SYSENTER and SYSEXIT */
+#define IA32_MSR_SYSENTER_CS    0x174
+#define IA32_MSR_SYSENTER_ESP   0x175
+#define IA32_MSR_SYSENTER_EIP   0x176
+
+#ifndef __ASM__
+
 #include <arch/pm.h>
 #include <arch/asm.h>
-
-#define EFLAGS_IF       (1 << 9)
-#define EFLAGS_RF       (1 << 16)
 
 typedef struct {
@@ -52 +61 @@
 } cpu_arch_t;
 
-
-#define CR4_OSFXSR_MASK (1<<9)
+#endif
 
 #endif

kernel/arch/ia32/src/asm.S

@@ -147 +147 @@
         popfl
 .endm   
+
+/*
+ * The SYSENTER syscall mechanism can be used for syscalls with
+ * four or fewer arguments. To pass these four arguments, we
+ * use four registers: EDX, ECX, EBX, ESI. The syscall number
+ * is passed in EAX. We use EDI to remember the return address
+ * and EBP to remember the stack. The INT-based syscall mechanism
+ * can actually handle six arguments plus the syscall number
+ * entirely in registers.
+ */
+.global sysenter_handler
+sysenter_handler:
+        pushl %ebp      # remember user stack
+        pushl %edi      # remember return user address
+
+        pushl %gs       # remember TLS
+
+        pushl %eax      # syscall number
+        subl $8, %esp   # unused sixth and fifth argument
+        pushl %esi      # fourth argument
+        pushl %ebx      # third argument
+        pushl %ecx      # second argument
+        pushl %edx      # first argument
+
+        movw $16, %ax
+        movw %ax, %ds
+        movw %ax, %es
+
+        cld
+        call syscall_handler
+        addl $28, %esp  # remove arguments from stack
+
+        pop %gs         # restore TLS
+
+        pop %edx        # prepare return EIP for SYSEXIT
+        pop %ecx        # prepare userspace ESP for SYSEXIT
+
+        sysexit         # return to userspace
+
 
 ## Declare interrupt handlers

kernel/arch/ia32/src/cpu/cpu.c

@@ -43 +43 @@
 
 #include <arch/smp/apic.h>
+#include <arch/syscall.h>
 
 /*
@@ -124 +125 @@
                 );
         }
+        
+        /* Setup fast SYSENTER/SYSEXIT syscalls */
+        syscall_setup_cpu();
 }
 

kernel/arch/ia32/src/proc/scheduler.c

@@ -59 +59 @@
 void before_thread_runs_arch(void)
 {
-        CPU->arch.tss->esp0 = (uintptr_t) &THREAD->kstack[THREAD_STACK_SIZE -
+        uintptr_t kstk = (uintptr_t) &THREAD->kstack[THREAD_STACK_SIZE -
             SP_DELTA];
+
+        /* Set kernel stack for CP3 -> CPL0 switch via SYSENTER */
+        write_msr(IA32_MSR_SYSENTER_ESP, kstk);
+
+        /* Set kernel stack for CPL3 -> CPL0 switch via interrupt */
+        CPU->arch.tss->esp0 = kstk;
         CPU->arch.tss->ss0 = selector(KDATA_DES);