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[PATCH 4.5 018/124] powerpc/process: Fix altivec SPR not being saved

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4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver O'Halloran <oohall@gmail.com>

commit 01d7c2a2de47890934faba91a71d183795e4348d upstream.

In save_sprs() in process.c contains the following test:

	if (cpu_has_feature(cpu_has_feature(CPU_FTR_ALTIVEC)))
		t->vrsave = mfspr(SPRN_VRSAVE);

CPU feature with the mask 0x1 is CPU_FTR_COHERENT_ICACHE so the test
is equivilent to:

	if (cpu_has_feature(CPU_FTR_ALTIVEC) &&
		cpu_has_feature(CPU_FTR_COHERENT_ICACHE))

On CPUs without support for both (i.e G5) this results in vrsave not
being saved between context switches. The vector register save/restore
code doesn't use VRSAVE to determine which registers to save/restore,
but the value of VRSAVE is used to determine if altivec is being used
in several code paths.

Fixes: 152d523e6307 ("powerpc: Create context switch helpers save_sprs() and restore_sprs()")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/powerpc/kernel/process.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -854,7 +854,7 @@ void restore_tm_state(struct pt_regs *re
 static inline void save_sprs(struct thread_struct *t)
 {
 #ifdef CONFIG_ALTIVEC
-	if (cpu_has_feature(cpu_has_feature(CPU_FTR_ALTIVEC)))
+	if (cpu_has_feature(CPU_FTR_ALTIVEC))
 		t->vrsave = mfspr(SPRN_VRSAVE);
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64

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[PATCH 4.5 000/124] 4.5.2-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 045/124] mlx4: add missing braces in verify_qp_parameters Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 007/124] parisc: Unbreak handling exceptions from kernel modules Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 047/124] ath9k: fix buffer overrun for ar9287 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 024/124] drm/radeon: add another R7 370 quirk Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 043/124] ipv4: Dont do expensive useless work during inetdev destroy. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 041/124] rocker: set FDB cleanup timer according to lowest ageing time Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 054/124] ipv4: fix broadcast packets reception Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 052/124] net: bcmgenet: fix dma api length mismatch Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 035/124] sh_eth: fix NULL pointer dereference in sh_eth_ring_format() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:40 +0200
  [PATCH 4.5 011/124] ALSA: hda - Apply fix for white noise on Asus N550JV, too Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 013/124] mm: fix invalid node in alloc_migrate_target() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 020/124] arm64: opcodes.h: Add arm big-endian config options before including arm header Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 010/124] ALSA: hda - Fix white noise on Asus N750JV headphone Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 015/124] s390/mm: handle PTE-mapped tail pages in fast gup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 018/124] powerpc/process: Fix altivec SPR not being saved Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 003/124] parisc: Fix SIGSYS signals in compat case Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 006/124] parisc: Fix kernel crash with reversed copy_from_user() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 019/124] compiler-gcc: disable -ftracer for __noclone functions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  [PATCH 4.5 016/124] libnvdimm: fix smart data retrieval Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-18 05:50 +0200
  Re: [PATCH 4.5 000/124] 4.5.2-stable review Guenter Roeck <linux@roeck-us.net> - 2016-04-18 18:40 +0200
    Re: [PATCH 4.5 000/124] 4.5.2-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-19 08:00 +0200
  Re: [PATCH 4.5 000/124] 4.5.2-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-04-18 18:40 +0200
    Re: [PATCH 4.5 000/124] 4.5.2-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-19 08:00 +0200
  Re: [PATCH 4.5 000/124] 4.5.2-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-19 08:00 +0200

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