This provides a facility which is intended for use by KVM, where the
contents of the FP/VSX and VMX (Altivec) registers can be saved away
to somewhere other than the thread_struct when kernel code wants to
use floating point or VMX instructions. This is done by providing a
pointer in the thread_struct to indicate where the state should be
saved to. The giveup_fpu() and giveup_altivec() functions test these
pointers and save state to the indicated location if they are non-NULL.
Note that the MSR_FP/VEC bits in task->thread.regs->msr are still used
to indicate whether the CPU register state is live, even when an
alternate save location is being used.
This also provides load_fp_state() and load_vr_state() functions, which
load up FP/VSX and VMX state from memory into the CPU registers, and
corresponding store_fp_state() and store_vr_state() functions, which
store FP/VSX and VMX state into memory from the CPU registers.
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
---
arch/powerpc/include/asm/processor.h | 7 +++++++
arch/powerpc/kernel/asm-offsets.c | 2 ++
arch/powerpc/kernel/fpu.S | 25 ++++++++++++++++++++++++-
arch/powerpc/kernel/ppc_ksyms.c | 4 ++++
arch/powerpc/kernel/process.c | 7 +++++++
arch/powerpc/kernel/vector.S | 29 +++++++++++++++++++++++++++--
6 files changed, 71 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 92f709d..8bc9d66 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -212,6 +212,7 @@ struct thread_struct {
#endif
#endif
struct thread_fp_state fp_state;
+ struct thread_fp_state *fp_save_area;
int fpexc_mode; /* floating-point exception mode */
unsigned int align_ctl; /* alignment handling control */
#ifdef CONFIG_PPC64
@@ -230,6 +231,7 @@ struct thread_struct {
unsigned long trap_nr; /* last trap # on this thread */
#ifdef CONFIG_ALTIVEC
struct thread_vr_state vr_state;
+ struct thread_vr_state *vr_save_area;
unsigned long vrsave;
int used_vr; /* set if process has used altivec */
#endif /* CONFIG_ALTIVEC */
@@ -359,6 +361,11 @@ extern int set_endian(struct task_struct *tsk, unsigned int val);
extern int get_unalign_ctl(struct task_struct *tsk, unsigned long adr);
extern int set_unalign_ctl(struct task_struct *tsk, unsigned int val);
+extern void load_fp_state(struct thread_fp_state *fp);
+extern void store_fp_state(struct thread_fp_state *fp);
+extern void load_vr_state(struct thread_vr_state *vr);
+extern void store_vr_state(struct thread_vr_state *vr);
+
static inline unsigned int __unpack_fe01(unsigned long msr_bits)
{
return ((msr_bits & MSR_FE0) >> 10) | ((msr_bits & MSR_FE1) >> 8);
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 38ebe36..9049197 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -90,9 +90,11 @@ int main(void)
#endif
DEFINE(THREAD_FPEXC_MODE, offsetof(struct thread_struct, fpexc_mode));
DEFINE(THREAD_FPSTATE, offsetof(struct thread_struct, fp_state));
+ DEFINE(THREAD_FPSAVEAREA, offsetof(struct thread_struct, fp_save_area));
DEFINE(FPSTATE_FPSCR, offsetof(struct thread_fp_state, fpscr));
#ifdef CONFIG_ALTIVEC
DEFINE(THREAD_VRSTATE, offsetof(struct thread_struct, vr_state));
+ DEFINE(THREAD_VRSAVEAREA, offsetof(struct thread_struct, vr_save_area));
DEFINE(THREAD_VRSAVE, offsetof(struct thread_struct, vrsave));
DEFINE(THREAD_USED_VR, offsetof(struct thread_struct, used_vr));
DEFINE(VRSTATE_VSCR, offsetof(struct thread_vr_state, vscr));
diff --git a/arch/powerpc/kernel/fpu.S b/arch/powerpc/kernel/fpu.S
index 34b96e6..4dca05e 100644
--- a/arch/powerpc/kernel/fpu.S
+++ b/arch/powerpc/kernel/fpu.S
@@ -81,6 +81,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
/*
+ * Load state from memory into FP registers including FPSCR.
+ * Assumes the caller has enabled FP in the MSR.
+ */
+_GLOBAL(load_fp_state)
+ lfd fr0,FPSTATE_FPSCR(r3)
+ MTFSF_L(fr0)
+ REST_32FPVSRS(0, R4, R3)
+ blr
+
+/*
+ * Store FP state into memory, including FPSCR
+ * Assumes the caller has enabled FP in the MSR.
+ */
+_GLOBAL(store_fp_state)
+ SAVE_32FPVSRS(0, R4, R3)
+ mffs fr0
+ stfd fr0,FPSTATE_FPSCR(r3)
+ blr
+
+/*
* This task wants to use the FPU now.
* On UP, disable FP for the task which had the FPU previously,
* and save its floating-point registers in its thread_struct.
@@ -172,9 +192,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
PPC_LCMPI 0,r3,0
beqlr- /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
+ PPC_LL r6,THREAD_FPSAVEAREA(r3)
PPC_LL r5,PT_REGS(r3)
- PPC_LCMPI 0,r5,0
+ PPC_LCMPI 0,r6,0
+ bne 2f
addi r6,r3,THREAD_FPSTATE
+2: PPC_LCMPI 0,r5,0
SAVE_32FPVSRS(0, R4, R6)
mffs fr0
stfd fr0,FPSTATE_FPSCR(r6)
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index 21646db..56a4bec 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -98,9 +98,13 @@ EXPORT_SYMBOL(start_thread);
#ifdef CONFIG_PPC_FPU
EXPORT_SYMBOL(giveup_fpu);
+EXPORT_SYMBOL(load_fp_state);
+EXPORT_SYMBOL(store_fp_state);
#endif
#ifdef CONFIG_ALTIVEC
EXPORT_SYMBOL(giveup_altivec);
+EXPORT_SYMBOL(load_vr_state);
+EXPORT_SYMBOL(store_vr_state);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_VSX
EXPORT_SYMBOL(giveup_vsx);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 94c1257..69785a5 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1007,6 +1007,11 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
p->thread.ptrace_bps[0] = NULL;
#endif
+ p->thread.fp_save_area = NULL;
+#ifdef CONFIG_ALTIVEC
+ p->thread.vr_save_area = NULL;
+#endif
+
#ifdef CONFIG_PPC_STD_MMU_64
if (mmu_has_feature(MMU_FTR_SLB)) {
unsigned long sp_vsid;
@@ -1113,9 +1118,11 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
current->thread.used_vsr = 0;
#endif
memset(¤t->thread.fp_state, 0, sizeof(current->thread.fp_state));
+ current->thread.fp_save_area = NULL;
#ifdef CONFIG_ALTIVEC
memset(¤t->thread.vr_state, 0, sizeof(current->thread.vr_state));
current->thread.vr_state.vscr.u[3] = 0x00010000; /* Java mode disabled */
+ current->thread.vr_save_area = NULL;
current->thread.vrsave = 0;
current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index a48df87..eacda4e 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -37,6 +37,28 @@ _GLOBAL(do_load_up_transact_altivec)
#endif
/*
+ * Load state from memory into VMX registers including VSCR.
+ * Assumes the caller has enabled VMX in the MSR.
+ */
+_GLOBAL(load_vr_state)
+ li r4,VRSTATE_VSCR
+ lvx vr0,r4,r3
+ mtvscr vr0
+ REST_32VRS(0,r4,r3)
+ blr
+
+/*
+ * Store VMX state into memory, including VSCR.
+ * Assumes the caller has enabled VMX in the MSR.
+ */
+_GLOBAL(store_vr_state)
+ SAVE_32VRS(0, r4, r3)
+ mfvscr vr0
+ li r4, VRSTATE_VSCR
+ stvx vr0, r4, r3
+ blr
+
+/*
* Disable VMX for the task which had it previously,
* and save its vector registers in its thread_struct.
* Enables the VMX for use in the kernel on return.
@@ -144,9 +166,12 @@ _GLOBAL(giveup_altivec)
PPC_LCMPI 0,r3,0
beqlr /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
- addi r7,r3,THREAD_VRSTATE
+ PPC_LL r7,THREAD_VRSAVEAREA(r3)
PPC_LL r5,PT_REGS(r3)
- PPC_LCMPI 0,r5,0
+ PPC_LCMPI 0,r7,0
+ bne 2f
+ addi r7,r3,THREAD_VRSTATE
+2: PPC_LCMPI 0,r5,0
SAVE_32VRS(0,r4,r7)
mfvscr vr0
li r4,VRSTATE_VSCR
--
1.8.4.rc3
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