linux-user: introduce functions to detect CPU type

Add a function to return ELF e_flags and use it to select the CPU model. Signed-off-by: YunQiang Su <[email protected]> [lv: split the patch and some cleanup in get_elf_eflags()] Signed-off-by: Laurent Vivier <[email protected]> Reviewed-by: Richard Henderson <[email protected]> Message-Id: <[email protected]>
dreddy · Feb 25, 2018 · 768fe76 · 768fe76
1 parent 542ca43
commit 768fe76
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Showing 3 changed files with 46 additions and 10 deletions.
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
@@ -2396,6 +2396,41 @@ static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias)
     g_free(syms);
 }
 
+uint32_t get_elf_eflags(int fd)
+{
+    struct elfhdr ehdr;
+    off_t offset;
+    int ret;
+
+    /* Read ELF header */
+    offset = lseek(fd, 0, SEEK_SET);
+    if (offset == (off_t) -1) {
+        return 0;
+    }
+    ret = read(fd, &ehdr, sizeof(ehdr));
+    if (ret < sizeof(ehdr)) {
+        return 0;
+    }
+    offset = lseek(fd, offset, SEEK_SET);
+    if (offset == (off_t) -1) {
+        return 0;
+    }
+
+    /* Check ELF signature */
+    if (!elf_check_ident(&ehdr)) {
+        return 0;
+    }
+
+    /* check header */
+    bswap_ehdr(&ehdr);
+    if (!elf_check_ehdr(&ehdr)) {
+        return 0;
+    }
+
+    /* return architecture id */
+    return ehdr.e_flags;
+}
+
 int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
 {
     struct image_info interp_info;

diff --git a/linux-user/main.c b/linux-user/main.c
@@ -4344,8 +4344,17 @@ int main(int argc, char **argv, char **envp)
 
     init_qemu_uname_release();
 
+    execfd = qemu_getauxval(AT_EXECFD);
+    if (execfd == 0) {
+        execfd = open(filename, O_RDONLY);
+        if (execfd < 0) {
+            printf("Error while loading %s: %s\n", filename, strerror(errno));
+            _exit(EXIT_FAILURE);
+        }
+    }
+
     if (cpu_model == NULL) {
-        cpu_model = cpu_get_model(0);
+        cpu_model = cpu_get_model(get_elf_eflags(execfd));
     }
     tcg_exec_init(0);
     /* NOTE: we need to init the CPU at this stage to get
@@ -4438,15 +4447,6 @@ int main(int argc, char **argv, char **envp)
     cpu->opaque = ts;
     task_settid(ts);
 
-    execfd = qemu_getauxval(AT_EXECFD);
-    if (execfd == 0) {
-        execfd = open(filename, O_RDONLY);
-        if (execfd < 0) {
-            printf("Error while loading %s: %s\n", filename, strerror(errno));
-            _exit(EXIT_FAILURE);
-        }
-    }
-
     ret = loader_exec(execfd, filename, target_argv, target_environ, regs,
         info, &bprm);
     if (ret != 0) {

diff --git a/linux-user/qemu.h b/linux-user/qemu.h
@@ -186,6 +186,7 @@ int loader_exec(int fdexec, const char *filename, char **argv, char **envp,
              struct target_pt_regs * regs, struct image_info *infop,
              struct linux_binprm *);
 
+uint32_t get_elf_eflags(int fd);
 int load_elf_binary(struct linux_binprm *bprm, struct image_info *info);
 int load_flt_binary(struct linux_binprm *bprm, struct image_info *info);