mips: FIx clone3 implementation (BZ 31325)

For o32 we need to setup a minimal stack frame to allow cprestore
on __thread_start_clone3 (which instruct the linker to save the
gp for PIC).  Also, there is no guarantee by kABI that $8 will be
preserved after syscall execution, so we need to save it on the
provided stack.

Checked on mipsel-linux-gnu.

Reported-by: Khem Raj <raj.khem@gmail.com>
Tested-by: Khem Raj <raj.khem@gmail.com>

diff --git a/sysdeps/unix/sysv/linux/mips/clone3.S b/sysdeps/unix/sysv/linux/mips/clone3.S
index e9fec2fa471b99baa0d01bdf5bb10e7fb9959c9d..481b8ae96366fc7011e206a40d44dfd8dad62c63 100644 (file)
--- a/sysdeps/unix/sysv/linux/mips/clone3.S
+++ b/sysdeps/unix/sysv/linux/mips/clone3.S
@@ -37,11 +37,6 @@
 
        .text
        .set            nomips16
-#if _MIPS_SIM == _ABIO32
-# define EXTRA_LOCALS 1
-#else
-# define EXTRA_LOCALS 0
-#endif
 #define FRAMESZ ((NARGSAVE*SZREG)+ALSZ)&ALMASK
 GPOFF= FRAMESZ-(1*SZREG)
 NESTED(__clone3, SZREG, sp)
@@ -68,8 +63,31 @@ NESTED(__clone3, SZREG, sp)
        beqz    a0, L(error)    /* No NULL cl_args pointer.  */
        beqz    a2, L(error)    /* No NULL function pointer.  */
 
+#if _MIPS_SIM == _ABIO32
+       /* Both stack and stack_size on clone_args are defined as uint64_t, and
+          there is no need to handle values larger than to 32 bits for o32.  */
+# if __BYTE_ORDER == __BIG_ENDIAN
+#  define CL_STACKPOINTER_OFFSET  44
+#  define CL_STACKSIZE_OFFSET     52
+# else
+#  define CL_STACKPOINTER_OFFSET  40
+#  define CL_STACKSIZE_OFFSET     48
+# endif
+
+       /* For o32 we need to setup a minimal stack frame to allow cprestore
+          on __thread_start_clone3.  Also there is no guarantee by kABI that
+          $8 will be preserved after syscall execution (so we need to save it
+          on the provided stack).  */
+       lw      t0, CL_STACKPOINTER_OFFSET(a0)  /* Load the stack pointer.  */
+       lw      t1, CL_STACKSIZE_OFFSET(a0)     /* Load the stack_size.  */
+       addiu   t1, -32                         /* Update the stack size.  */
+       addu    t2, t1, t0                      /* Calculate the thread stack.  */
+       sw      a3, 0(t2)                       /* Save argument pointer.  */
+       sw      t1, CL_STACKSIZE_OFFSET(a0)     /* Save the new stack size.  */
+#else
        move    $8, a3          /* a3 is set to 0/1 for syscall success/error
                                   while a4/$8 is returned unmodified.  */
+#endif
 
        /* Do the system call, the kernel expects:
           v0: system call number
@@ -125,7 +143,11 @@ L(thread_start_clone3):
 
        /* Restore the arg for user's function.  */
        move            t9, a2          /* Function pointer.  */
+#if _MIPS_SIM == _ABIO32
+       PTR_L           a0, 0(sp)
+#else
        move            a0, $8          /* Argument pointer.  */
+#endif
 
        /* Call the user's function.  */
        jal             t9