[gdb/testsuite] use -Ttext-segment for jit-elf tests

Removes the need to manually relocate loaded ELF binary by using a fixed
constant as both mmap base address and as a requested first segment
address supplied to the linker.

In future will enable JIT tests with a valid DWARF debug info.  Current
tests still need to compile without a debug info though, because they do
a function name modification.

gdb/testsuite/ChangeLog:

2020-02-18  Mihails Strasuns  <mihails.strasuns@intel.com>

	* lib/jit-elf-helpers.exp: Supply -Ttext-segment linker flag and
	  define LOAD_ADDRESS/LOAD_INCREMENT macros for the compiled binaries.
	* gdb.base/jit-elf-main.c: Use LOAD_ADDRESS/LOAD_INCREMENT to
	  calculate the mmap address.

1 files changed, 15 insertions, 12 deletions

diff --git a/gdb/testsuite/gdb.base/jit-elf-main.c b/gdb/testsuite/gdb.base/jit-elf-main.c
index acfd17d4179..be7185ef1a1 100644
--- a/gdb/testsuite/gdb.base/jit-elf-main.c
+++ b/gdb/testsuite/gdb.base/jit-elf-main.c
@@ -51,20 +51,16 @@ usage (void)
   exit (1);
 }
 
-/* Update .p_vaddr and .sh_addr as if the code was JITted to ADDR.  */
+/* Rename jit_function_XXXX to match idx  */
 
 static void
-update_locations (const void *const addr, int idx)
+update_name (const void *const addr, int idx)
 {
   const ElfW (Ehdr) *const ehdr = (ElfW (Ehdr) *)addr;
   ElfW (Shdr) *const shdr = (ElfW (Shdr) *)((char *)addr + ehdr->e_shoff);
   ElfW (Phdr) *const phdr = (ElfW (Phdr) *)((char *)addr + ehdr->e_phoff);
   int i;
 
-  for (i = 0; i < ehdr->e_phnum; ++i)
-    if (phdr[i].p_type == PT_LOAD)
-      phdr[i].p_vaddr += (ElfW (Addr))addr;
-
   for (i = 0; i < ehdr->e_shnum; ++i)
     {
       if (shdr[i].sh_type == SHT_STRTAB)
@@ -81,9 +77,6 @@ update_locations (const void *const addr, int idx)
             if (strcmp (p, "jit_function_XXXX") == 0)
               sprintf (p, "jit_function_%04d", idx);
         }
-
-      if (shdr[i].sh_flags & SHF_ALLOC)
-        shdr[i].sh_addr += (ElfW (Addr))addr;
     }
 }
 
@@ -96,6 +89,15 @@ update_locations (const void *const addr, int idx)
 #define MAIN main
 #endif
 
+/* Must be defined by .exp file when compiling to know
+   what address to map the ELF binary to.  */
+#ifndef LOAD_ADDRESS
+#error "Must define LOAD_ADDRESS"
+#endif
+#ifndef LOAD_INCREMENT
+#error "Must define LOAD_INCREMENT"
+#endif
+
 /* Used to spin waiting for GDB.  */
 volatile int wait_for_gdb = ATTACH;
 #define WAIT_FOR_GDB do {} while (wait_for_gdb)
@@ -139,8 +141,9 @@ MAIN (int argc, char *argv[])
 	  exit (1);
 	}
 
-      const void *const addr = mmap (0, st.st_size, PROT_READ|PROT_WRITE,
-				     MAP_PRIVATE, fd, 0);
+      void *load_addr = (void *) (size_t) (LOAD_ADDRESS + (i - 1) * LOAD_INCREMENT);
+      const void *const addr = mmap (load_addr, st.st_size, PROT_READ|PROT_WRITE,
+				     MAP_PRIVATE | MAP_FIXED, fd, 0);
       struct jit_code_entry *const entry = calloc (1, sizeof (*entry));
 
       if (addr == MAP_FAILED)
@@ -149,7 +152,7 @@ MAIN (int argc, char *argv[])
 	  exit (1);
 	}
 
-      update_locations (addr, i);
+      update_name (addr, i);
 
       /* Link entry at the end of the list.  */
       entry->symfile_addr = (const char *)addr;