sparc: Fix system call tracing register handling.

A system call trace trigger on entry allows the tracing
process to inspect and potentially change the traced
process's registers.

Account for that by reloading the %g1 (syscall number)
and %i0-%i5 (syscall argument) values.  We need to be
careful to revalidate the range of %g1, and reload the
system call table entry it corresponds to into %l7.

Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/arch/sparc/kernel/entry.S b/arch/sparc/kernel/entry.S
index 33c02b15f47859a8262677d08635fcfdbb8872cb..a83707c83be803b78b3019cac6dde9dba2cfabd6 100644 (file)
--- a/arch/sparc/kernel/entry.S
+++ b/arch/sparc/kernel/entry.S
@@ -948,7 +948,24 @@ linux_syscall_trace:
        cmp     %o0, 0
        bne     3f
         mov    -ENOSYS, %o0
+
+       /* Syscall tracing can modify the registers.  */
+       ld      [%sp + STACKFRAME_SZ + PT_G1], %g1
+       sethi   %hi(sys_call_table), %l7
+       ld      [%sp + STACKFRAME_SZ + PT_I0], %i0
+       or      %l7, %lo(sys_call_table), %l7
+       ld      [%sp + STACKFRAME_SZ + PT_I1], %i1
+       ld      [%sp + STACKFRAME_SZ + PT_I2], %i2
+       ld      [%sp + STACKFRAME_SZ + PT_I3], %i3
+       ld      [%sp + STACKFRAME_SZ + PT_I4], %i4
+       ld      [%sp + STACKFRAME_SZ + PT_I5], %i5
+       cmp     %g1, NR_syscalls
+       bgeu    3f
+        mov    -ENOSYS, %o0
+
+       sll     %g1, 2, %l4
        mov     %i0, %o0
+       ld      [%l7 + %l4], %l7
        mov     %i1, %o1
        mov     %i2, %o2
        mov     %i3, %o3

diff --git a/arch/sparc/kernel/syscalls.S b/arch/sparc/kernel/syscalls.S
index bb0008927598b1f7bbeeccdf30c6fa154219a4ce..c4a1b5c40e4efc7ed17bcc0d67d1f058ea4f09f8 100644 (file)
--- a/arch/sparc/kernel/syscalls.S
+++ b/arch/sparc/kernel/syscalls.S
@@ -158,7 +158,25 @@ linux_syscall_trace32:
         add    %sp, PTREGS_OFF, %o0
        brnz,pn %o0, 3f
         mov    -ENOSYS, %o0
+
+       /* Syscall tracing can modify the registers.  */
+       ldx     [%sp + PTREGS_OFF + PT_V9_G1], %g1
+       sethi   %hi(sys_call_table32), %l7
+       ldx     [%sp + PTREGS_OFF + PT_V9_I0], %i0
+       or      %l7, %lo(sys_call_table32), %l7
+       ldx     [%sp + PTREGS_OFF + PT_V9_I1], %i1
+       ldx     [%sp + PTREGS_OFF + PT_V9_I2], %i2
+       ldx     [%sp + PTREGS_OFF + PT_V9_I3], %i3
+       ldx     [%sp + PTREGS_OFF + PT_V9_I4], %i4
+       ldx     [%sp + PTREGS_OFF + PT_V9_I5], %i5
+
+       cmp     %g1, NR_syscalls
+       bgeu,pn %xcc, 3f
+        mov    -ENOSYS, %o0
+
+       sll     %g1, 2, %l4
        srl     %i0, 0, %o0
+       lduw    [%l7 + %l4], %l7
        srl     %i4, 0, %o4
        srl     %i1, 0, %o1
        srl     %i2, 0, %o2
@@ -170,7 +188,25 @@ linux_syscall_trace:
         add    %sp, PTREGS_OFF, %o0
        brnz,pn %o0, 3f
         mov    -ENOSYS, %o0
+
+       /* Syscall tracing can modify the registers.  */
+       ldx     [%sp + PTREGS_OFF + PT_V9_G1], %g1
+       sethi   %hi(sys_call_table64), %l7
+       ldx     [%sp + PTREGS_OFF + PT_V9_I0], %i0
+       or      %l7, %lo(sys_call_table64), %l7
+       ldx     [%sp + PTREGS_OFF + PT_V9_I1], %i1
+       ldx     [%sp + PTREGS_OFF + PT_V9_I2], %i2
+       ldx     [%sp + PTREGS_OFF + PT_V9_I3], %i3
+       ldx     [%sp + PTREGS_OFF + PT_V9_I4], %i4
+       ldx     [%sp + PTREGS_OFF + PT_V9_I5], %i5
+
+       cmp     %g1, NR_syscalls
+       bgeu,pn %xcc, 3f
+        mov    -ENOSYS, %o0
+
+       sll     %g1, 2, %l4
        mov     %i0, %o0
+       lduw    [%l7 + %l4], %l7
        mov     %i1, %o1
        mov     %i2, %o2
        mov     %i3, %o3