linux-user/elfload: Move PT_INTERP detection to first loop

For BTI, we need to know if the executable is static or dynamic,
which means looking for PT_INTERP earlier.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201021173749.111103-8-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 31 insertions, 29 deletions

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 210592aa90..107a628a9e 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2421,8 +2421,10 @@ static void load_elf_image(const char *image_name, int image_fd,
 
     mmap_lock();
 
-    /* Find the maximum size of the image and allocate an appropriate
-       amount of memory to handle that.  */
+    /*
+     * Find the maximum size of the image and allocate an appropriate
+     * amount of memory to handle that.  Locate the interpreter, if any.
+     */
     loaddr = -1, hiaddr = 0;
     info->alignment = 0;
     for (i = 0; i < ehdr->e_phnum; ++i) {
@@ -2438,6 +2440,33 @@ static void load_elf_image(const char *image_name, int image_fd,
             }
             ++info->nsegs;
             info->alignment |= eppnt->p_align;
+        } else if (eppnt->p_type == PT_INTERP && pinterp_name) {
+            g_autofree char *interp_name = NULL;
+
+            if (*pinterp_name) {
+                errmsg = "Multiple PT_INTERP entries";
+                goto exit_errmsg;
+            }
+            interp_name = g_malloc(eppnt->p_filesz);
+            if (!interp_name) {
+                goto exit_perror;
+            }
+
+            if (eppnt->p_offset + eppnt->p_filesz <= BPRM_BUF_SIZE) {
+                memcpy(interp_name, bprm_buf + eppnt->p_offset,
+                       eppnt->p_filesz);
+            } else {
+                retval = pread(image_fd, interp_name, eppnt->p_filesz,
+                               eppnt->p_offset);
+                if (retval != eppnt->p_filesz) {
+                    goto exit_perror;
+                }
+            }
+            if (interp_name[eppnt->p_filesz - 1] != 0) {
+                errmsg = "Invalid PT_INTERP entry";
+                goto exit_errmsg;
+            }
+            *pinterp_name = g_steal_pointer(&interp_name);
         }
     }
 
@@ -2590,33 +2619,6 @@ static void load_elf_image(const char *image_name, int image_fd,
             if (vaddr_em > info->brk) {
                 info->brk = vaddr_em;
             }
-        } else if (eppnt->p_type == PT_INTERP && pinterp_name) {
-            g_autofree char *interp_name = NULL;
-
-            if (*pinterp_name) {
-                errmsg = "Multiple PT_INTERP entries";
-                goto exit_errmsg;
-            }
-            interp_name = g_malloc(eppnt->p_filesz);
-            if (!interp_name) {
-                goto exit_perror;
-            }
-
-            if (eppnt->p_offset + eppnt->p_filesz <= BPRM_BUF_SIZE) {
-                memcpy(interp_name, bprm_buf + eppnt->p_offset,
-                       eppnt->p_filesz);
-            } else {
-                retval = pread(image_fd, interp_name, eppnt->p_filesz,
-                               eppnt->p_offset);
-                if (retval != eppnt->p_filesz) {
-                    goto exit_perror;
-                }
-            }
-            if (interp_name[eppnt->p_filesz - 1] != 0) {
-                errmsg = "Invalid PT_INTERP entry";
-                goto exit_errmsg;
-            }
-            *pinterp_name = g_steal_pointer(&interp_name);
 #ifdef TARGET_MIPS
         } else if (eppnt->p_type == PT_MIPS_ABIFLAGS) {
             Mips_elf_abiflags_v0 abiflags;