Subject: ACPI: Add the MWAIT C-state mask to avoid overflow
From: Zhao Yakui <yakui.zhao@xxxxxxxxx>
The Cx Register address obtained from the _CST object is used as the mait
hints if the register type is FFixedHW. And it is used to check whether
the Cx type is supported or not.
On some boxes the following Cx state package is obtained from _CST object:
>{
ResourceTemplate ()
{
Register (FFixedHW,
0x01, // Bit Width
0x02, // Bit Offset
0x0000000000889759, // Address
0x03, // Access Size
)
},
0x03,
0xF5,
0x015E }
In such case we should use the bit[7:4] of Cx address to check whether
the Cx type is supported or not.
Add the MWAIT C-state mask to avoid overflow
Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Acked-by:Venki Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
---
arch/x86/kernel/acpi/cstate.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
Index: linux-2.6/arch/x86/kernel/acpi/cstate.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/cstate.c
+++ linux-2.6/arch/x86/kernel/acpi/cstate.c
@@ -56,6 +56,7 @@ static struct cstate_entry *cpu_cstate_e
static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
#define MWAIT_SUBSTATE_MASK (0xf)
+#define MWAIT_CSTATE_MASK (0xf)
#define MWAIT_SUBSTATE_SIZE (4)
#define CPUID_MWAIT_LEAF (5)
@@ -98,7 +99,8 @@ int acpi_processor_ffh_cstate_probe(unsi
cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
/* Check whether this particular cx_type (in CST) is supported or not */
- cstate_type = (cx->address >> MWAIT_SUBSTATE_SIZE) + 1;
+ cstate_type = ((cx->address >> MWAIT_SUBSTATE_SIZE) &
+ MWAIT_CSTATE_MASK) + 1;
edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
