Relocate binaries that conflict with the pk's address space

Of course, this is only possible for PIEs, e.g. the dynamic linker.

3 files changed, 13 insertions, 19 deletions

diff --git a/pk/elf.c b/pk/elf.c
index 79ee756..28760eb 100644
--- a/pk/elf.c
+++ b/pk/elf.c
@@ -21,6 +21,11 @@ void load_elf(const char* fn, elf_info* info)
         eh64.e_ident[2] == 'L'    && eh64.e_ident[3] == 'F'))
     goto fail;
 
+  size_t bias = 0;
+  extern char _end;
+  if (eh64.e_type == ET_DYN)
+    bias = ROUNDUP((uintptr_t)&_end, RISCV_PGSIZE);
+
   #define LOAD_ELF do { \
     eh = (typeof(eh))&eh64; \
     size_t phdr_size = eh->e_phnum*sizeof(*ph); \
@@ -29,16 +34,17 @@ void load_elf(const char* fn, elf_info* info)
     info->phdr = info->phdr_top - phdr_size; \
     ssize_t ret = file_pread(file, (void*)info->phdr, phdr_size, eh->e_phoff); \
     if (ret < (ssize_t)phdr_size) goto fail; \
-    info->entry = eh->e_entry; \
+    info->entry = bias + eh->e_entry; \
     info->phnum = eh->e_phnum; \
     info->phent = sizeof(*ph); \
     ph = (typeof(ph))info->phdr; \
     for(int i = 0; i < eh->e_phnum; i++, ph++) { \
-      if(ph->p_type == SHT_PROGBITS && ph->p_memsz) { \
-        info->brk_min = MAX(info->brk_min, ph->p_vaddr + ph->p_memsz); \
+      if(ph->p_type == PT_LOAD && ph->p_memsz) { \
+        info->brk_min = MAX(info->brk_min, bias + ph->p_vaddr + ph->p_memsz); \
         size_t vaddr = ROUNDDOWN(ph->p_vaddr, RISCV_PGSIZE), prepad = ph->p_vaddr - vaddr; \
         size_t memsz = ph->p_memsz + prepad, filesz = ph->p_filesz + prepad; \
         size_t offset = ph->p_offset - prepad; \
+        vaddr += bias; \
         if (__do_mmap(vaddr, filesz, -1, MAP_FIXED|MAP_PRIVATE, file, offset) != vaddr) \
           goto fail; \
         size_t mapped = ROUNDUP(filesz, RISCV_PGSIZE); \
diff --git a/pk/elf.h b/pk/elf.h
index dfe6c63..a05ccf2 100644
--- a/pk/elf.h
+++ b/pk/elf.h
@@ -12,8 +12,10 @@
 #define IS_ELF32(hdr) (IS_ELF(hdr) && (hdr).e_ident[4] == 1)
 #define IS_ELF64(hdr) (IS_ELF(hdr) && (hdr).e_ident[4] == 2)
 
-#define SHT_PROGBITS 1
-#define SHT_NOBITS   8
+#define ET_EXEC 2
+#define ET_DYN 3
+
+#define PT_LOAD 1
 
 #define AT_NULL   0
 #define AT_PHDR   3
diff --git a/pk/pk.ld b/pk/pk.ld
index 1bad03a..6a93b32 100644
--- a/pk/pk.ld
+++ b/pk/pk.ld
@@ -87,18 +87,4 @@ SECTIONS
   /* End of uninitialized data segment (used by syscalls.c for heap) */
   PROVIDE( end = . );
   _end = .;
-
-  /*--------------------------------------------------------------------*/
-  /* Special gcc sections (this was in idt32.ld)                        */
-  /*--------------------------------------------------------------------*/
-
-  .mdebug.abi32        0 : { KEEP(*(.mdebug.abi32))        }
-  .mdebug.abiN32       0 : { KEEP(*(.mdebug.abiN32))       }
-  .mdebug.abi64        0 : { KEEP(*(.mdebug.abi64))        }
-  .mdebug.abiO64       0 : { KEEP(*(.mdebug.abiO64))       }
-  .mdebug.eabi32       0 : { KEEP(*(.mdebug.eabi32))       }
-  .mdebug.eabi64       0 : { KEEP(*(.mdebug.eabi64))       }
-  .gcc_compiled_long32 0 : { KEEP(*(.gcc_compiled_long32)) }
-  .gcc_compiled_long64 0 : { KEEP(*(.gcc_compiled_long64)) }
-
 }