Re: [PATCH] arm: Move trampolines into code section

[Vladimir 'phcoder' Serbinenko]

LGTM

On Tue, 30 Apr 2019, 10:12 Alexander Graf, <address@hidden> wrote:

When creating T32->A32 transition jumps, the relocation code in grub
will generate trampolines. These trampolines live in the .data section
of our PE binary which means they are not marked as executable.

This misbehavior was unmasked by commit a51f953f4ee87 ("mkimage: Align
efi sections on 4k boundary") which made the X/NX boundary more obvious
because everything became page aligned.

To put things into proper order, let's move the arm trampolines into the
.text section instead. That way everyone knows they are executable.

Fixes: a51f953f4ee87 ("mkimage: Align efi sections on 4k boundary")
Reported-by: Julien ROBIN <address@hidden>
Reported-by: Leif Lindholm <address@hidden>

Signed-off-by: Alexander Graf <address@hidden>
---
 util/grub-mkimagexx.c | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/util/grub-mkimagexx.c b/util/grub-mkimagexx.c
index 2059890c3..af23fae52 100644
--- a/util/grub-mkimagexx.c
+++ b/util/grub-mkimagexx.c
@@ -2197,25 +2197,10 @@ SUFFIX (locate_sections) (Elf_Ehdr *e, const char *kernel_path,
          }
       }

-  layout->kernel_size = ALIGN_UP (layout->kernel_size + image_target->vaddr_offset,
-                             image_target->section_align)
-    - image_target->vaddr_offset;
-  layout->exec_size = layout->kernel_size;
-
-  /* .data */
-  for (i = 0, s = smd->sections;
-       i < smd->num_sections;
-       i++, s = (Elf_Shdr *) ((char *) s + smd->section_entsize))
-    if (SUFFIX (is_data_section) (s, image_target))
-      layout->kernel_size = SUFFIX (put_section) (s, i, layout->kernel_size, smd,
-                                                 image_target);
-
 #ifdef MKIMAGE_ELF32
   if (image_target->elf_target == EM_ARM)
     {
       grub_size_t tramp;
-      layout->kernel_size = ALIGN_UP (layout->kernel_size + image_target->vaddr_offset,
-                                     image_target->section_align) - image_target->vaddr_offset;

       layout->kernel_size = ALIGN_UP (layout->kernel_size, 16);

@@ -2223,10 +2208,22 @@ SUFFIX (locate_sections) (Elf_Ehdr *e, const char *kernel_path,
                                       smd->num_sections, image_target);

       layout->tramp_off = layout->kernel_size;
-      layout->kernel_size += ALIGN_UP (tramp, 16);
     }
 #endif

+  layout->kernel_size = ALIGN_UP (layout->kernel_size + image_target->vaddr_offset,
+                             image_target->section_align)
+    - image_target->vaddr_offset;
+  layout->exec_size = layout->kernel_size;
+
+  /* .data */
+  for (i = 0, s = smd->sections;
+       i < smd->num_sections;
+       i++, s = (Elf_Shdr *) ((char *) s + smd->section_entsize))
+    if (SUFFIX (is_data_section) (s, image_target))
+      layout->kernel_size = SUFFIX (put_section) (s, i, layout->kernel_size, smd,
+                                                 image_target);
+
   layout->bss_start = layout->kernel_size;
   layout->end = layout->kernel_size;

--
2.16.4


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