[RFC,3/5] Reuse code to relocate trampoline

Commit Message

Frediano Ziglio Sept. 4, 2024, 2:56 p.m. UTC

---
 xen/arch/x86/boot/Makefile             |  6 +++---
 xen/arch/x86/boot/build32.lds.S        |  4 ++++
 xen/arch/x86/boot/head.S               | 24 ++--------------------
 xen/arch/x86/boot/reloc-trampoline.c   | 28 ++++++++++++++++++++++++++
 xen/arch/x86/boot/reloc-trampoline64.c |  1 +
 xen/arch/x86/efi/efi-boot.h            | 15 ++------------
 6 files changed, 40 insertions(+), 38 deletions(-)
 create mode 100644 xen/arch/x86/boot/reloc-trampoline.c
 create mode 120000 xen/arch/x86/boot/reloc-trampoline64.c

Patch

diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index ed8d55866d..42fd1721de 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -1,6 +1,6 @@ 
-obj-bin-y += head.o cbundle.o
+obj-bin-y += head.o cbundle.o reloc-trampoline64.o
 
-head-bin-objs := cmdline.o reloc.o
+head-bin-objs := cmdline.o reloc.o reloc-trampoline.o
 
 nocov-y   += $(head-bin-objs)
 noubsan-y += $(head-bin-objs)
@@ -43,7 +43,7 @@  $(obj)/cbundle.o: $(head-bin-objs) $(obj)/build32.other.lds $(obj)/build32.final
 	$(PYTHON) $(srctree)/tools/make_output \
 		--script $(obj)/build32.final.lds \
 		--bin1 $@.1.bin --bin2 $@.2.bin \
-		--map $(obj)/cbundle.map --exports cmdline_parse_early,reloc \
+		--map $(obj)/cbundle.map --exports cmdline_parse_early,reloc,reloc_trampoline32 \
 		--section-header '.section .init.text, "ax", @progbits' \
 		--output $(obj)/cbundle.s
 	$(CC) -c $(obj)/cbundle.s -o $@.tmp
diff --git a/xen/arch/x86/boot/build32.lds.S b/xen/arch/x86/boot/build32.lds.S
index 87d2a589b5..0b7341edeb 100644
--- a/xen/arch/x86/boot/build32.lds.S
+++ b/xen/arch/x86/boot/build32.lds.S
@@ -43,6 +43,10 @@  SECTIONS
          * Potentially they should be all variables. */
         DECLARE_IMPORT(__base_relocs_start);
         DECLARE_IMPORT(__base_relocs_end);
+        DECLARE_IMPORT(__trampoline_rel_start);
+        DECLARE_IMPORT(__trampoline_rel_stop);
+        DECLARE_IMPORT(__trampoline_seg_start);
+        DECLARE_IMPORT(__trampoline_seg_stop);
         . = . + GAP;
         *(.text)
         *(.text.*)
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 791a1fee80..8e35f2a791 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -817,28 +817,8 @@  trampoline_setup:
         mov     %edx, sym_offs(l1_bootmap)(%esi, %ecx, 8)
 
         /* Apply relocations to bootstrap trampoline. */
-        mov     sym_esi(trampoline_phys), %edx
-        lea     sym_esi(__trampoline_rel_start), %edi
-        lea     sym_esi(__trampoline_rel_stop), %ecx
-1:
-        mov     (%edi), %eax
-        add     %edx, (%edi, %eax)
-        add     $4,%edi
-
-        cmp     %ecx, %edi
-        jb      1b
-
-        /* Patch in the trampoline segment. */
-        shr     $4,%edx
-        lea     sym_esi(__trampoline_seg_start), %edi
-        lea     sym_esi(__trampoline_seg_stop), %ecx
-1:
-        mov     (%edi), %eax
-        mov     %dx, (%edi, %eax)
-        add     $4,%edi
-
-        cmp     %ecx, %edi
-        jb      1b
+        mov     sym_esi(trampoline_phys), %eax
+        call    reloc_trampoline32
 
         /* Do not parse command line on EFI platform here. */
         cmpb    $0, sym_esi(efi_platform)
diff --git a/xen/arch/x86/boot/reloc-trampoline.c b/xen/arch/x86/boot/reloc-trampoline.c
new file mode 100644
index 0000000000..2a48890483
--- /dev/null
+++ b/xen/arch/x86/boot/reloc-trampoline.c
@@ -0,0 +1,28 @@ 
+
+#include <xen/stdint.h>
+
+#pragma GCC visibility push(hidden)
+extern const int32_t __trampoline_rel_start[], __trampoline_rel_stop[];
+extern const int32_t __trampoline_seg_start[], __trampoline_seg_stop[];
+#pragma GCC visibility pop
+
+#if defined(__i386__)
+void reloc_trampoline32(unsigned long phys)
+#elif defined (__x86_64__)
+void reloc_trampoline64(unsigned long phys)
+#else
+#error Unknow architecture
+#endif
+{
+    const int32_t *trampoline_ptr;
+
+    /* Apply relocations to trampoline. */
+    for ( trampoline_ptr = __trampoline_rel_start;
+          trampoline_ptr < __trampoline_rel_stop;
+          ++trampoline_ptr )
+        *(uint32_t *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
+    for ( trampoline_ptr = __trampoline_seg_start;
+          trampoline_ptr < __trampoline_seg_stop;
+          ++trampoline_ptr )
+        *(uint16_t *)(*trampoline_ptr + (long)trampoline_ptr) = phys >> 4;
+}
diff --git a/xen/arch/x86/boot/reloc-trampoline64.c b/xen/arch/x86/boot/reloc-trampoline64.c
new file mode 120000
index 0000000000..20d6dfae1a
--- /dev/null
+++ b/xen/arch/x86/boot/reloc-trampoline64.c
@@ -0,0 +1 @@ 
+reloc-trampoline.c
\ No newline at end of file
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index f282358435..87a7f8abcf 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -101,27 +101,16 @@  static void __init efi_arch_relocate_image(unsigned long delta)
     }
 }
 
-extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[];
-extern const s32 __trampoline_seg_start[], __trampoline_seg_stop[];
+void reloc_trampoline64(unsigned long phys);
 
 static void __init relocate_trampoline(unsigned long phys)
 {
-    const s32 *trampoline_ptr;
-
     trampoline_phys = phys;
 
     if ( !efi_enabled(EFI_LOADER) )
         return;
 
-    /* Apply relocations to trampoline. */
-    for ( trampoline_ptr = __trampoline_rel_start;
-          trampoline_ptr < __trampoline_rel_stop;
-          ++trampoline_ptr )
-        *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
-    for ( trampoline_ptr = __trampoline_seg_start;
-          trampoline_ptr < __trampoline_seg_stop;
-          ++trampoline_ptr )
-        *(u16 *)(*trampoline_ptr + (long)trampoline_ptr) = phys >> 4;
+    reloc_trampoline64(phys);
 }
 
 static void __init place_string(u32 *addr, const char *s)