PERFORCE change 29755 for review

[Peter Wemm]

http://perforce.freebsd.org/chv.cgi?CH=29755

Change 29755 by peter at peter_daintree on 2003/04/25 18:21:54

	Add a stub 32 bit 'syscall' entry point so that we can point
	MSR_CSTAR to it.  Note that GUCODE32_SEL exists but does not
	have the 'p' (present) bit set, so theoretically this is
	impossible.

Affected files ...

.. //depot/projects/hammer/sys/x86_64/x86_64/exception.s#31 edit
.. //depot/projects/hammer/sys/x86_64/x86_64/machdep.c#86 edit

Differences ...

==== //depot/projects/hammer/sys/x86_64/x86_64/exception.s#31 (text+ko) ====

@@ -259,6 +259,14 @@
 	andq	$~PCB_FULLCTX,PCB_FLAGS(%rax)
 	jmp	doreti
 
+/*
+ * Here for CYA insurance, in case a "syscall" instruction gets
+ * issued from 32 bit compatability mode. MSR_CSTAR has to point
+ * to *something* if EFER_SCE is enabled.
+ */
+IDTVEC(fast_syscall32)
+	sysret
+
 ENTRY(fork_trampoline)
 	movq	%r12, %rdi		/* function */
 	movq	%rbx, %rsi		/* arg1 */

==== //depot/projects/hammer/sys/x86_64/x86_64/machdep.c#86 (text+ko) ====

@@ -151,7 +151,7 @@
 struct kva_md_info kmi;
 
 static struct trapframe proc0_tf;
-struct pcpu __pcpu;
+static struct pcpu __pcpu;
 
 struct mtx icu_lock;
 
@@ -653,7 +653,8 @@
 	IDTVEC(bnd), IDTVEC(ill), IDTVEC(dna), IDTVEC(fpusegm),
 	IDTVEC(tss), IDTVEC(missing), IDTVEC(stk), IDTVEC(prot),
 	IDTVEC(page), IDTVEC(mchk), IDTVEC(rsvd), IDTVEC(fpu), IDTVEC(align),
-	IDTVEC(xmm), IDTVEC(int0x80_syscall), IDTVEC(fast_syscall);
+	IDTVEC(xmm), IDTVEC(int0x80_syscall),
+	IDTVEC(fast_syscall), IDTVEC(fast_syscall32);
 
 void
 sdtossd(sd, ssd)
@@ -1260,6 +1261,7 @@
 	msr = rdmsr(MSR_EFER) | EFER_SCE;
 	wrmsr(MSR_EFER, msr);
 	wrmsr(MSR_LSTAR, (u_int64_t)IDTVEC(fast_syscall));
+	wrmsr(MSR_CSTAR, (u_int64_t)IDTVEC(fast_syscall32));
 	msr = ((u_int64_t)GSEL(GCODE_SEL, SEL_KPL) << 32) |
 	      ((u_int64_t)GSEL(GUCODE32_SEL, SEL_UPL) << 48);
 	wrmsr(MSR_STAR, msr);