libsandbox: improve sparc trace code a bit more

This gets most of the tests passing, but syscall canceling still
does not work.  Need to talk to upstream to figure it out.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 26 insertions, 8 deletions

diff --git a/libsandbox/trace/linux/sparc.c b/libsandbox/trace/linux/sparc.c
index f410b73..b59a036 100644
--- a/libsandbox/trace/linux/sparc.c
+++ b/libsandbox/trace/linux/sparc.c
@@ -1,20 +1,28 @@
 #define SB_NO_TRACE_ARCH
 #if 0 /* XXX: broken sometimes #293632 */
 
-/* Indexes into the pt_regs.u_reg[] array -- UREG_XX from kernel are all off
- * by 1 and use Ix instead of Ox.  These work for both 32 and 64 bit Linux.
+/* Since sparc's g0 register is hardcoded to 0 in the ISA, the kernel does not
+ * bother copying it out when using the regs ptrace.  Instead it shifts things
+ * by one and stores [g1..g7] in [0..6] and [o0..o7] in [7..14] (leaving the
+ * last u_reg[15] unused).
+ *
+ * Oddly, the kernel defines are not adjusted to the values as they written in
+ * the register structure -- UREG_G0 is 0, UREG_G1 is 1, etc...  So we have to
+ * define our own to get correct behavior.  Also, the kernel uses UREG_I# when
+ * it's easier for us to think of it in terms of UREG_O# (register windows!).
+ *
+ * This should work for both 32 and 64 bit Linux userland.
  */
 #define U_REG_G1 0
 #define U_REG_O0 7
 
-static int trace_sysnum_regs(void *vregs)
-{
-	trace_regs *regs = vregs;
-	return regs->u_regs[U_REG_G1] ? : SB_SYS_EXECVE;
-}
-
+/* Sparc systems have swapped the addr/data args. */
 #undef trace_get_regs
 #define trace_get_regs(regs) do_ptrace(PTRACE_GETREGS, regs, NULL)
+#undef trace_set_regs
+#define trace_set_regs(regs) do_ptrace(PTRACE_SETREGS, regs, NULL)
+
+#define trace_reg_sysnum u_regs[U_REG_G1]
 
 static long trace_raw_ret(void *vregs)
 {
@@ -22,6 +30,16 @@ static long trace_raw_ret(void *vregs)
 	return regs->u_regs[U_REG_O0];
 }
 
+static void trace_set_ret(void *vregs, int err)
+{
+	trace_regs *regs = vregs;
+	/* The carry bit is used to flag errors. */
+	regs->psr |= PSR_C;
+	/* Userland negates the value on sparc. */
+	regs->u_regs[U_REG_O0] = err;
+	trace_set_regs(regs);
+}
+
 static unsigned long trace_arg(void *vregs, int num)
 {
 	trace_regs *regs = vregs;