Changeset 5010

Timestamp:

Aug 22, 2006, 1:06:42 AM (18 years ago)

Author:

Gary Byers

Message:

Unbox %arg_z (boxed entrypoint) earlier in _SPffcall, before entering foreign
context. (Need to check PPC version(s) as well.)

Use DARWIN_GS_HACK to swap %gs memory around when transitioning between foreign
code and lisp.

File:

• trunk/ccl/lisp-kernel/x86-spentry64.s (modified) (5 diffs)

trunk/ccl/lisp-kernel/x86-spentry64.s

@@ -3961 +3961 @@
 
 _spentry(ffcall)
+        /* Unbox %arg_z.  It's either a fixnum or macptr (or bignum) ;
+          if not a fixnum, get the first word */
+        __(unbox_fixnum(%arg_z,%imm0))
+        __(testb $fixnummask,%arg_z_b)
+        __(je 0f)
+        __(movq macptr.address(%arg_z),%imm0)
+0:              
         /* Save lisp registers   */
         __(push %temp0)
@@ -3982 +3989 @@
         __(movq $TCR_STATE_FOREIGN,%rcontext:tcr.valence)
         __(emms)
+        __(ldmxcsr %rcontext:tcr.foreign_mxcsr)
         __(movq (%rsp),%rbp)
-        __(ldmxcsr %rcontext:tcr.foreign_mxcsr)
+        __ifdef([DARWIN_GS_HACK])
+         /* At this point, %imm0=%rax is live (contains
+            the entrypoint); the lisp registers are
+            all saved, and the foreign arguments are
+            on the foreign stack (about to be popped
+            off).  Save the linear TCR address in %save0/%r15
+            so that we can restore it later, and preserve
+            the entrypoint somewhere where C won't bash it.
+            Note that dereferencing the entrypoint from
+            foreign code has never been safe (unless it's
+            a fixnum */
+         __(save_tcr_linear(%save0))
+         __(movq %imm0,%save1)
+         __(set_foreign_gs_base())
+         __(movq %save1,%imm0)
+        __endif
         __(addq $2*node_size,%rsp)
-        __(unbox_fixnum(%arg_z,%r11))
-        __(testb $fixnummask,%arg_z_b)
-        __(movq %arg_z,%r10)
         __(pop %rdi)
         __(pop %rsi)
         __(pop %rdx)
-        __(je 0f)
-        __(mov macptr.address(%r10),%r11)
-0:              
         __(pop %rcx)
         __(pop %r8)
         __(pop %r9)
-        __(call *%r11)
+        __(call *%rax)
         __(movq %rbp,%rsp)
+        __ifdef([DARWIN_GS_HACK])
+         /* %rax/%rdx contains the return value (maybe), %save0 still
+            contains the linear tcr address.  Preserve %rax/%rdx here. */
+         __(movq %rax,%save1)
+         __(movq %rdx,%save2)
+         __(set_gs_base(%save0))
+         __(movq %save1,%rax)
+         __(movq %save2,%rdx)
+        __endif
         __(movq %rsp,%rcontext:tcr.foreign_sp)        
         __(clr %save3)
@@ -4064 +4090 @@
         __(pop %r9)
         __(syscall)
-        __ifdef([FREEBSD])
-        __(jnc 0f)
-        __(negq %rax)
+        __ifdef([SYSCALL_SETS_CARRY_ON_ERROR])
+         __(jnc 0f)
+         __(negq %rax)
 0:      
         __endif        
@@ -4214 +4240 @@
         __(movq %r12,%r11)
         __(call *%rax)
+        __ifdef([DARWIN_GS_HACK])
+         /* linear TCR address in now in %rax; callback index was
+            saved in %r12 a moment ago. */
+         __(set_gs_base(%rax))
+         __(movq %r12,%r11)
+        __endif
 1:      /* Align foreign stack for lisp   */
         __(subq $node_size,%rsp)
@@ -4255 +4287 @@
         __(addq $node_size,%rsp)
         __(ldmxcsr %rcontext:tcr.foreign_mxcsr)
+        __ifdef([DARWIN_GS_HACK])
+         /* Lucky us; nothing is live here */
+         __(set_foreign_gs_base())
+        __endif
         __(pop %rbp)
         __(pop %rbx)