Removed dependency on correct user stack for syscall. Simplified code slightly as...

diff --git a/kernel/src/boot.S b/kernel/src/boot.S
index f595ff9f79ae6d853dba5bd415b1a66057be8bc2..7bfad4ea74cb6c6903d107fd480ab4ee8827ba29 100644 (file)
--- a/kernel/src/boot.S
+++ b/kernel/src/boot.S
@@ -128,6 +128,7 @@ phys_mem_map: .skip 0x1000 * 128 - 8
 .align 16
 stack_bottom:
 .skip 4096 * 4 # 16KiB
+.globl stack_top
 stack_top:
 interrupt_stack_bottom:
 .skip 4096 * 4 # 16KiB

diff --git a/kernel/src/ring3.S b/kernel/src/ring3.S
index a3a0e7698a21ff9bb42d736556e57905026f1993..dd2335451a4519ee7c6e8d7ff5e1760d695a637f 100644 (file)
--- a/kernel/src/ring3.S
+++ b/kernel/src/ring3.S
@@ -37,30 +37,30 @@ load_tss:
 
 .globl syscall_64bit_handler
 syscall_64bit_handler:
-       push %rax
+       mov %rax, rax_save
        movq current_pid, %rax
        shl $17, %rax # * 0x1000 * 32 (i.e. the size of a process)
        addq process_struct_table, %rax
        # %rax now contains the address of the current process struct.
        movq %rcx, 0x10(%rax) # %rip
        movq %rbx, 0x18(%rax)
-       movq %rsp, 0x20(%rax) # original %rsp
-       addq $8, 0x20(%rax) # here as well
+       movq %rsp, 0x20(%rax)
        movq %rbp, 0x28(%rax)
        movq %r12, 0x30(%rax)
        movq %r13, 0x38(%rax)
        movq %r14, 0x40(%rax)
        movq %r15, 0x48(%rax)
        fstcw 0x58(%rax)
-       # Current process registers have now all been updated.
-       pop %rax
+       # Current process registers have now all been saved.
+       mov rax_save, %rax
 
        mov %r10, %rcx
        cmp $syscall_n, %rax
+       mov $stack_top, %rsp # Setup stack
        jae incorrect_syscall
        callq *syscalls_call_table(, %rax, 8)
 syscall_end:
-       movq %rax, %rbp
+       mov %rax, rax_save
        movq current_pid, %rax
        shl $17, %rax # * 0x1000 * 32 (i.e. the size of a process)
        addq process_struct_table, %rax
@@ -68,15 +68,14 @@ syscall_end:
        movq 0x10(%rax), %rcx # %rip
        movq 0x18(%rax), %rbx
        movq 0x20(%rax), %rsp
-       push %rbp # %rax
        movq 0x28(%rax), %rbp
        movq 0x30(%rax), %r12
        movq 0x38(%rax), %r13
        movq 0x40(%rax), %r14
        movq 0x48(%rax), %r15
        fldcw 0x58(%rax)
-       # Current process registers have now all been updated.
-       pop %rax
+       # Current process registers have now all been loaded.
+       mov rax_save, %rax
        sysretq
 incorrect_syscall:
        call syscall_rax_error_handler
@@ -89,3 +88,6 @@ syscalls_call_table:
        .quad syscall_print_low_mmap
 .set syscall_n, 3
 process_struct_table: .quad 0xFFFFC00000000000
+
+.section .data
+rax_save: .quad 1