[PATCH 4/6] powerpc: Define ppr in thread_struct

[Haren Myneni]

[PATCH 4/6] powerpc: Define ppr in thread_struct

ppr in thread_struct is used to save PPR and restore it before process exits
from kernel.

This patch sets the default priority to 3 when tasks are created such
that users can use 4 for higher priority tasks.

Signed-off-by: Haren Myneni <ha...@us.ibm.com>
---
 arch/powerpc/include/asm/processor.h |    6 ++++++
 arch/powerpc/kernel/asm-offsets.c    |    1 +
 arch/powerpc/kernel/process.c        |    2 ++
 3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h 
b/arch/powerpc/include/asm/processor.h
index 8750204..7db5df4 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -245,6 +245,7 @@ struct thread_struct {
 #ifdef CONFIG_PPC64
        unsigned long   dscr;
        int             dscr_inherit;
+       unsigned long   ppr;
 #endif
 };
 
@@ -270,6 +271,10 @@ struct thread_struct {
        SPEFSCR_INIT \
 }
 #else
+/* Default SMT priority is 3. Use 11- 13bits to save priority. */
+/* .ppr is used to save/restore only on P7 or later processors */
+#define INIT_PPR (3ull << 50)
+
 #define INIT_THREAD  { \
        .ksp = INIT_SP, \
        .ksp_limit = INIT_SP_LIMIT, \
@@ -278,6 +283,7 @@ struct thread_struct {
        .fpr = {{0}}, \
        .fpscr = { .val = 0, }, \
        .fpexc_mode = 0, \
+       .ppr = INIT_PPR, \
 }
 #endif
 
diff --git a/arch/powerpc/kernel/asm-offsets.c 
b/arch/powerpc/kernel/asm-offsets.c
index 7523539..41f65ec 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -77,6 +77,7 @@ int main(void)
        DEFINE(NMI_MASK, NMI_MASK);
        DEFINE(THREAD_DSCR, offsetof(struct thread_struct, dscr));
        DEFINE(THREAD_DSCR_INHERIT, offsetof(struct thread_struct, 
dscr_inherit));
+       DEFINE(TASKTHREADPPR, offsetof(struct task_struct, thread.ppr));
 #else
        DEFINE(THREAD_INFO, offsetof(struct task_struct, stack));
 #endif /* CONFIG_PPC64 */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ba48233..2563acc 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -814,6 +814,8 @@ int copy_thread(unsigned long clone_flags, unsigned long 
usp,
                p->thread.dscr_inherit = current->thread.dscr_inherit;
                p->thread.dscr = current->thread.dscr;
        }
+       if (cpu_has_feature(CPU_FTR_HAS_PPR))
+               p->thread.ppr = INIT_PPR;
 #endif
        /*
         * The PPC64 ABI makes use of a TOC to contain function 
-- 
1.7.1



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