binfmt_elf_fdpic: support auxvec base platform string

Commit 483fad1c3fa1060d7e6710e84a065ad514571739 ("ELF loader support for
auxvec base platform string") introduced AT_BASE_PLATFORM, but only
implemented it for binfmt_elf.

Given that AT_VECTOR_SIZE_BASE is unconditionally enlarged for us, and
it's only optionally added in for the platforms that set
ELF_BASE_PLATFORM, wire it up for binfmt_elf_fdpic, too.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 43 insertions, 7 deletions

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 80c1f952ef78..e4eb472558ca 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -455,6 +455,16 @@ error_kill:
 }
 
 /*****************************************************************************/
+
+#ifndef ELF_BASE_PLATFORM
+/*
+ * AT_BASE_PLATFORM indicates the "real" hardware/microarchitecture.
+ * If the arch defines ELF_BASE_PLATFORM (in asm/elf.h), the value
+ * will be copied to the user stack in the same manner as AT_PLATFORM.
+ */
+#define ELF_BASE_PLATFORM NULL
+#endif
+
 /*
  * present useful information to the program
  */
@@ -466,8 +476,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
         unsigned long sp, csp, nitems;
         elf_caddr_t __user *argv, *envp;
         size_t platform_len = 0, len;
-        char *k_platform;
-        char __user *u_platform, *p;
+        char *k_platform, *k_base_platform;
+        char __user *u_platform, *u_base_platform, *p;
         long hwcap;
         int loop;
         int nr; /* reset for each csp adjustment */
@@ -483,11 +493,14 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
                 return -EFAULT;
 #endif
 
-        /* get hold of platform and hardware capabilities masks for the machine
-         * we are running on.  In some cases (Sparc), this info is impossible
-         * to get, in others (i386) it is merely difficult.
-         */
         hwcap = ELF_HWCAP;
+
+        /*
+         * If this architecture has a platform capability string, copy it
+         * to userspace.  In some cases (Sparc), this info is impossible
+         * for userspace to get any other way, in others (i386) it is
+         * merely difficult.
+         */
         k_platform = ELF_PLATFORM;
         u_platform = NULL;
 
@@ -499,6 +512,21 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
                         return -EFAULT;
         }
 
+        /*
+         * If this architecture has a "base" platform capability
+         * string, copy it to userspace.
+         */
+        k_base_platform = ELF_BASE_PLATFORM;
+        u_base_platform = NULL;
+
+        if (k_base_platform) {
+                platform_len = strlen(k_base_platform) + 1;
+                sp -= platform_len;
+                u_base_platform = (char __user *) sp;
+                if (__copy_to_user(u_base_platform, k_base_platform, platform_len) != 0)
+                        return -EFAULT;
+        }
+
 #if defined(__i386__) && defined(CONFIG_SMP)
         /* in some cases (e.g. Hyper-Threading), we want to avoid L1 evictions
          * by the processes running on the same package. One thing we can do is
@@ -543,7 +571,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
         /* force 16 byte _final_ alignment here for generality */
 #define DLINFO_ITEMS 13
 
-        nitems = 1 + DLINFO_ITEMS + (k_platform ? 1 : 0) + AT_VECTOR_SIZE_ARCH;
+        nitems = 1 + DLINFO_ITEMS + (k_platform ? 1 : 0) +
+                (k_base_platform ? 1 : 0) + AT_VECTOR_SIZE_ARCH;
 
         csp = sp;
         sp -= nitems * 2 * sizeof(unsigned long);
@@ -575,6 +604,13 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
                             (elf_addr_t) (unsigned long) u_platform);
         }
 
+        if (k_base_platform) {
+                nr = 0;
+                csp -= 2 * sizeof(unsigned long);
+                NEW_AUX_ENT(AT_BASE_PLATFORM,
+                            (elf_addr_t) (unsigned long) u_base_platform);
+        }
+
         nr = 0;
         csp -= DLINFO_ITEMS * 2 * sizeof(unsigned long);
         NEW_AUX_ENT(AT_HWCAP,   hwcap);