[PATCH] powerpc: Remove lppaca structure from the PACA

At present the lppaca - the structure shared with the iSeries
hypervisor and phyp - is contained within the PACA, our own low-level
per-cpu structure.  This doesn't have to be so, the patch below
removes it, making a separate array of lppaca structures.

This saves approximately 500*NR_CPUS bytes of image size and kernel
memory, because we don't need aligning gap between the Linux and
hypervisor portions of every PACA.  On the other hand it means an
extra level of dereference in many accesses to the lppaca.

The patch also gets rid of several places where we assign the paca
address to a local variable for no particular reason.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 24 insertions, 12 deletions

diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index 999bdd816769..5d1b708086bd 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -25,6 +25,28 @@
  * field correctly */
 extern unsigned long __toc_start;
 
+/*
+ * iSeries structure which the hypervisor knows about - this structure
+ * should not cross a page boundary.  The vpa_init/register_vpa call
+ * is now known to fail if the lppaca structure crosses a page
+ * boundary.  The lppaca is also used on POWER5 pSeries boxes.  The
+ * lppaca is 640 bytes long, and cannot readily change since the
+ * hypervisor knows its layout, so a 1kB alignment will suffice to
+ * ensure that it doesn't cross a page boundary.
+ */
+struct lppaca lppaca[] = {
+        [0 ... (NR_CPUS-1)] = {
+                .desc = 0xd397d781,     /* "LpPa" */
+                .size = sizeof(struct lppaca),
+                .dyn_proc_status = 2,
+                .decr_val = 0x00ff0000,
+                .fpregs_in_use = 1,
+                .end_of_quantum = 0xfffffffffffffffful,
+                .slb_count = 64,
+                .vmxregs_in_use = 0,
+        },
+};
+
 /* The Paca is an array with one entry per processor.  Each contains an
  * lppaca, which contains the information shared between the
  * hypervisor and Linux.
@@ -35,27 +57,17 @@ extern unsigned long __toc_start;
  * processor (not thread).
  */
 #define PACA_INIT_COMMON(number, start, asrr, asrv)                         \
+        .lppaca_ptr = &lppaca[number],                                      \
         .lock_token = 0x8000,                                               \
         .paca_index = (number),         /* Paca Index */                    \
         .kernel_toc = (unsigned long)(&__toc_start) + 0x8000UL,             \
         .stab_real = (asrr),            /* Real pointer to segment table */ \
         .stab_addr = (asrv),            /* Virt pointer to segment table */ \
         .cpu_start = (start),           /* Processor start */               \
-        .hw_cpu_id = 0xffff,                                                \
-        .lppaca = {                                                         \
-                .desc = 0xd397d781,     /* "LpPa" */                        \
-                .size = sizeof(struct lppaca),                              \
-                .dyn_proc_status = 2,                                       \
-                .decr_val = 0x00ff0000,                                     \
-                .fpregs_in_use = 1,                                         \
-                .end_of_quantum = 0xfffffffffffffffful,                     \
-                .slb_count = 64,                                            \
-                .vmxregs_in_use = 0,                                        \
-        },                                                                  \
+        .hw_cpu_id = 0xffff,
 
 #ifdef CONFIG_PPC_ISERIES
 #define PACA_INIT_ISERIES(number)                                           \
-        .lppaca_ptr = &paca[number].lppaca,                                 \
         .reg_save_ptr = &iseries_reg_save[number],
 
 #define PACA_INIT(number)                                                   \