Adjust PT_MIPS_ABIFLAGS segment if present

When loading the executable on MIPS, the dynamic loader looks for MIPS
ABI flags using PT_MIPS_ABIFLAGS header. The flags themselves are stored
in the .MIPS.abiflags section, so the header must be updated when the
section is moved.

Here we also import PT_MIPS_ABIFLAGS definition from glibc commit
0bd956720c457ff054325b48f26ac7c91cb060e8.

Closes: #82
Signed-off-by: Ivan A. Melnikov <[email protected]>

Author: iv-m

src/elf.h

@@ -1574,9 +1574,10 @@ typedef struct
 
 /* Legal values for p_type field of Elf32_Phdr.  */
 
-#define PT_MIPS_REGINFO	0x70000000	/* Register usage information */
-#define PT_MIPS_RTPROC  0x70000001	/* Runtime procedure table. */
-#define PT_MIPS_OPTIONS 0x70000002
+#define PT_MIPS_REGINFO	  0x70000000	/* Register usage information. */
+#define PT_MIPS_RTPROC	  0x70000001	/* Runtime procedure table. */
+#define PT_MIPS_OPTIONS	  0x70000002
+#define PT_MIPS_ABIFLAGS  0x70000003	/* FP mode requirement. */
 
 /* Special program header types.  */
 

src/patchelf.cc

@@ -766,6 +766,18 @@ void ElfFile<ElfFileParamNames>::writeReplacedSections(Elf_Off & curOff,
                 }
         }
 
+        /* If there is .MIPS.abiflags section, then the PT_MIPS_ABIFLAGS
+           segment must be sync'ed with it. */
+        if (sectionName == ".MIPS.abiflags") {
+            for (auto & phdr : phdrs) {
+                if (rdi(phdr.p_type) == PT_MIPS_ABIFLAGS) {
+                    phdr.p_offset = shdr.sh_offset;
+                    phdr.p_vaddr = phdr.p_paddr = shdr.sh_addr;
+                    phdr.p_filesz = phdr.p_memsz = shdr.sh_size;
+                }
+            }
+        }
+
         curOff += roundUp(i.second.size(), sectionAlignment);
     }