loader: move x64-specific stuff from premain

move the arch-specific stuff in premain to
arch/x64/arch-setup.cc.

Introduce arch_init_premain() and arch_setup_tls().

arch_init_premain() is supposed to perform arch-specific
initialization before the common premain code is run.

arch_setup_tls() is run _after_ the common setup_tls code.

Reviewed-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

arch/x64/arch-setup.cc

@@ -10,6 +10,8 @@
 #include <osv/mempool.hh>
 #include <osv/mmu.hh>
 #include "processor.hh"
+#include "msr.hh"
+#include "xen.hh"
 #include <osv/elf.hh>
 #include <osv/types.h>
 #include <alloca.h>
@@ -188,3 +190,19 @@ void arch_setup_free_memory()
         mmu::free_initial_memory_range(ent.addr, ent.size);
     });
 }
+
+void arch_setup_tls(thread_control_block *tcb)
+{
+    processor::wrmsr(msr::IA32_FS_BASE, reinterpret_cast<uint64_t>(tcb));
+}
+
+static inline void disable_pic()
+{
+    // PIC not present in Xen
+    XENPV_ALTERNATIVE({ processor::outb(0xff, 0x21); processor::outb(0xff, 0xa1); }, {});
+}
+
+void arch_init_premain()
+{
+    disable_pic();
+}

arch/x64/arch-setup.hh

@@ -8,6 +8,11 @@
 #ifndef ARCH_SETUP_HH_
 #define ARCH_SETUP_HH_
 
+#include <osv/tls.hh>
+
+void arch_init_premain();
+void arch_setup_tls(thread_control_block *tcb);
+
 void arch_setup_free_memory();
 
 #endif /* ARCH_SETUP_HH_ */

loader.cc

@@ -14,12 +14,10 @@
 #include <cctype>
 #include <osv/elf.hh>
 #include <osv/tls.hh>
-#include "msr.hh"
 #include "exceptions.hh"
 #include <osv/debug.hh>
 #include "drivers/pci.hh"
 #include "smp.hh"
-#include "xen.hh"
 #include "ioapic.hh"
 
 #include "drivers/acpi.hh"
@@ -36,6 +34,7 @@
 #include "drivers/pvpanic.hh"
 #include <osv/barrier.hh>
 #include "arch.hh"
+#include "arch-setup.hh"
 #include "osv/trace.hh"
 #include <osv/power.hh>
 #include <osv/rcu.hh>
@@ -72,7 +71,8 @@ void setup_tls(elf::init_table inittab)
     memcpy(tcb0, inittab.tls.start, inittab.tls.size);
     auto p = reinterpret_cast<thread_control_block*>(tcb0 + inittab.tls.size);
     p->self = p;
-    processor::wrmsr(msr::IA32_FS_BASE, reinterpret_cast<uint64_t>(p));
+
+    arch_setup_tls(p);
 }
 
 extern "C" {
@@ -82,16 +82,10 @@ extern "C" {
     void ramdisk_init(void);
 }
 
-
-void disable_pic()
-{
-    // PIC not present in Xen
-    XENPV_ALTERNATIVE({ outb(0xff, 0x21); outb(0xff, 0xa1); }, {});
-}
-
 void premain()
 {
-    disable_pic();
+    arch_init_premain();
+
     auto inittab = elf::get_init(elf_header);
     setup_tls(inittab);
     boot_time.event("TLS initialization");