Hi Denys,
> Just to be sure that we only fall back if PTRACE_GETREGS op is
> unknown, not in other cases (such as tracee killed under us) lets do
> this:
>
> if (get_regs_error && errno == ????)
>
> Which errno is generated in this case?
Makes sense. We get -EIO back if PTRACE_GETREGS is not available.
Tested on SLES10 (2.6.16).
Anton
--
PTRACE_GETREGS was added to the ppc kernel in 2.6.23. In order to
provide backward compatibility for very old kernels, add a manual
fallback.
* syscall.c (powerpc_getreg, powerpc_getregs_old): New functions.
(get_regs): use it
Index: b/syscall.c
===================================================================
--- a/syscall.c
+++ b/syscall.c
@@ -994,6 +994,55 @@ undefined_scno_name(struct tcb *tcp)
return buf;
}
+#ifdef POWERPC
+/*
+ * PTRACE_GETREGS was added to the PowerPC kernel in v2.6.23, so we
+ * provide a slow fallback for very old kernels.
+ */
+
+static long powerpc_getreg(pid_t pid, unsigned long offset, unsigned long *p)
+{
+ long val;
+
+ errno = 0;
+ val = ptrace(PTRACE_PEEKUSER, pid, (char *)offset, 0);
+ if (val == -1 && errno)
+ return -1;
+
+ *p = val;
+ return 0;
+}
+
+static long powerpc_getregs_old(pid_t pid)
+{
+ int i;
+ long r;
+
+ r = powerpc_getreg(pid, sizeof(unsigned long) * PT_MSR, &ppc_regs.msr);
+ if (r)
+ goto out;
+
+ r = powerpc_getreg(pid, sizeof(unsigned long) * PT_CCR, &ppc_regs.ccr);
+ if (r)
+ goto out;
+
+ r = powerpc_getreg(pid, sizeof(unsigned long) * PT_ORIG_R3,
+ &ppc_regs.orig_gpr3);
+ if (r)
+ goto out;
+
+ for (i = 0; i <= 8; i++) {
+ r = powerpc_getreg(pid, sizeof(unsigned long) * (PT_R0+i),
+ &ppc_regs.gpr[i]);
+ if (r)
+ goto out;
+ }
+
+out:
+ return r;
+}
+#endif
+
#ifndef get_regs
long get_regs_error;
@@ -1042,6 +1091,8 @@ get_regs(pid_t pid)
get_regs_error = ptrace(PTRACE_GETREGS, pid, (char *)&sparc_regs, 0);
# elif defined(POWERPC)
get_regs_error = ptrace(PTRACE_GETREGS, pid, NULL, (long) &ppc_regs);
+ if (get_regs_error && errno == EIO)
+ get_regs_error = powerpc_getregs_old(pid);
/* try PTRACE_GETREGSET first, fallback to PTRACE_GETREGS */
# else
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