[Xen-changelog] [xen staging] The hvmloader binary generated when using LLVM LD doesn't work

[patchbot@xxxxxxx]

commit 09b3907f93fe023ebca809c9f706f3d022801dce
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Sep 3 17:54:12 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Sep 3 17:54:12 2018 +0200

    The hvmloader binary generated when using LLVM LD doesn't work
    properly and seems to get stuck while trying to generate and load the
    ACPI tables. This is caused by the layout of the binary when linked
    with LLVM LD.
    
    LLVM LD has a different default linker script that GNU LD, and the
    resulting hvmloader binary is slightly different:
    
    LLVM LD:
    Program Headers:
      Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
      PHDR           0x000034 0x000ff034 0x000ff034 0x00060 0x00060 R   0x4
      LOAD           0x000000 0x000ff000 0x000ff000 0x38000 0x38000 RWE 0x1000
      GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0
    
    GNU LD:
    Program Headers:
      Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
      LOAD           0x000080 0x00100000 0x00100000 0x36308 0x3fd74 RWE 0x10
      GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0x4
    
    Note that in the LLVM LD case (as with GNU LD) the .text section does
    indeed have the address set to 0x100000 as requested on the command
    line:
    
    [ 1] .text             PROGBITS        00100000 001000 00dd10 00  AX  0   0 
16
    
    There's however the PHDR which is not present when using GNU LD.
    
    Fix this by using a very simple linker script that generates the same
    binary regardless of whether LLVM or GNU LD is used. By using a linker
    script the usage of -Ttext can also be avoided by placing the desired
    .text load address directly in the linker script.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 tools/firmware/hvmloader/Makefile      |  7 ++-----
 tools/firmware/hvmloader/hvmloader.lds | 13 +++++++++++++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/tools/firmware/hvmloader/Makefile 
b/tools/firmware/hvmloader/Makefile
index 496ac72b77..e980ce7c5f 100644
--- a/tools/firmware/hvmloader/Makefile
+++ b/tools/firmware/hvmloader/Makefile
@@ -20,9 +20,6 @@
 XEN_ROOT = $(CURDIR)/../../..
 include $(XEN_ROOT)/tools/firmware/Rules.mk
 
-
-LOADADDR = 0x100000
-
 # SMBIOS spec requires format mm/dd/yyyy
 SMBIOS_REL_DATE ?= $(shell date +%m/%d/%Y)
 
@@ -82,8 +79,8 @@ vpath build.c $(ACPI_PATH)
 vpath static_tables.c $(ACPI_PATH)
 OBJS += $(ACPI_OBJS)
 
-hvmloader: $(OBJS)
-       $(LD) $(LDFLAGS_DIRECT) -N -Ttext $(LOADADDR) -o $@ $^
+hvmloader: $(OBJS) hvmloader.lds
+       $(LD) $(LDFLAGS_DIRECT) -N -T hvmloader.lds -o $@ $(OBJS)
 
 roms.inc: $(ROMS)
        echo "/* Autogenerated file. DO NOT EDIT */" > $@.new
diff --git a/tools/firmware/hvmloader/hvmloader.lds 
b/tools/firmware/hvmloader/hvmloader.lds
new file mode 100644
index 0000000000..4471d7af27
--- /dev/null
+++ b/tools/firmware/hvmloader/hvmloader.lds
@@ -0,0 +1,13 @@
+SECTIONS
+{
+  . = 0x100000;
+  /*
+   * NB: there's no need to use the AT keyword in order to set the LMA, by
+   * default the linker will use VMA = LMA unless specified otherwise.
+   */
+  .text : { *(.text) *(.text.*) }
+  .rodata : { *(.rodata) *(.rodata.*) }
+  .data : { *(.data) *(.data.*) }
+  .bss : { *(.bss) *(.bss.*) }
+  _end = .;
+}
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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