[PATCH] Detect 64-bit-ness in PowerPC Book III-E

Yao Qi
2014-12-11T11:15:50Z

This patch is to teach GDBServer to detect 64-bit inferior correctly.
We find a problem that GDBServer is unable to detect on an e5500 core
processor. Current GDBServer assumes that MSR is a 64-bit register,
but MSR is a 32-bit register in Book III-E. This patch is to fix this
problem by checking both bits in MSR, in order to handle both Book
III-S and Book III-E.

Is it OK?

gdb/gdbserver:

2014-12-11 Yao Qi <yao@codesourcery.com>

* linux-ppc-low.c (ppc_arch_setup) [__powerpc64__]: Change
variable msr to type 'unsigned long'. Check bit 63 or bit 31
is one.
---
gdb/gdbserver/linux-ppc-low.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/gdb/gdbserver/linux-ppc-low.c b/gdb/gdbserver/linux-ppc-low.c
index 8fd4b38..0c0ced6 100644
--- a/gdb/gdbserver/linux-ppc-low.c
+++ b/gdb/gdbserver/linux-ppc-low.c
@@ -401,7 +401,7 @@ ppc_arch_setup (void)
{
const struct target_desc *tdesc;
#ifdef __powerpc64__
- long msr;
+ unsigned long msr;
struct regcache *regcache;

/* On a 64-bit host, assume 64-bit inferior process with no
@@ -411,13 +411,17 @@ ppc_arch_setup (void)
current_process ()->tdesc = tdesc;
ppc_hwcap = 0;

- /* Only if the high bit of the MSR is set, we actually have
- a 64-bit inferior. */
+ /* We actually have a 64-bit inferior only if the certain bit of the
+ MSR is set. The PowerISA Book III-S MSR is different from the
+ PowerISA Book III-E MSR. The Book III-S MSR is 64 bits wide, and
+ its MSR[SF] is the bit 0 of a 64-bit value. Book III-E MSR is 32
+ bits wide, and its MSR[CM] is the bit 0 of a 32-bit value. We check
+ both here. */
regcache = new_register_cache (tdesc);
fetch_inferior_registers (regcache, find_regno (tdesc, "msr"));
collect_register_by_name (regcache, "msr", &msr);
free_register_cache (regcache);
- if (msr < 0)
+ if (msr & 0x8000000080000000)
{
ppc_get_hwcap (&ppc_hwcap);
if (ppc_hwcap & PPC_FEATURE_CELL)
--
1.9.3