[PATCH] powerpc64/linux: Fix 64-bit process detection for Book III-E
James.Yang at freescale.com
Thu Oct 17 16:29:01 UTC 2013
strace does not detect 64-bit processes on PowerISA Book III-E processors
such as Freescale P5020 and T4240.
The PowerISA Book III-S MSR is different from the PowerISA Book III-E
MSR. The III-S MSR is 64 bits wide, and its MSR[SF] is the msb (bit 0
of a 64-bit value). III-E MSR is 32 bits wide, and its MSR[CM] is the
msb (bit 0 of a 32-bit value).
On Linux powerpc 64-bit, ppc_regs.msr is an unsigned long, which is a
The III-E MSR[SF] is bit 32 of ppc_regs.msr.
The III-S MSR[CM] is bit 0 of ppc_regs.msr.
This patch adds a test for the bit in ppc_regs.msr corresponding to
III-E's MSR[CM] bit so that 64-bit processes are correctly detected.
syscall.c | 18 ++++++++++++++++--
1 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/syscall.c b/syscall.c
index 3477dcd..5bf3e5a 100644
@@ -1222,8 +1222,22 @@ get_scno(struct tcb *tcp)
/* Check for 64/32 bit mode. */
- /* SF is bit 0 of MSR */
- if ((ppc_regs.msr >> 63) & 1)
+ /* In Book III-S, SF is bit 0 of MSR, which is 64-bits wide.
+ * In Book III-E, CM is bit 0 of MSR, which is 32-bits wide,
+ * and it is stored in the lower 32 bits of ppc_regs.msr.
+ * ppc_regs.msr meaning
+ * bit 0 bit 32 III-S III-E
+ * 0 0 32-bit 32-bit
+ * 0 1 32-bit 64-bit
+ * 1 0 64-bit not possible
+ * 1 1 64-bit not possible
+ * In case III-S MSR bit 32 ever becomes a non-reserved bit, test
+ * ppc_regs.msr bit 0 first since it will always be 0 for III-E.
+ if (((ppc_regs.msr >> 63) & 1) || (ppc_regs.msr >> 31) & 1)
currpers = 0;
currpers = 1;
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