From 1195892c091a15cc862f4e202482a36adc924e12 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Fri, 2 Jun 2017 18:43:30 -0300 Subject: powerpc/kernel: Fix FP and vector register restoration Currently tsk->thread->load_vec and load_fp are not initialized during task creation, which can lead to garbage values in these variables (non-zero values). These variables will be checked later in restore_math() to validate if the FP and vector registers are being utilized. Since these values might be non-zero, the restore_math() will continue to save the FP and vectors even if they were never utilized by the userspace application. load_fp and load_vec counters will then overflow (they wrap at 255) and the FP and Altivec will be finally disabled, but before that condition is reached (counter overflow) several context switches will have restored FP and vector registers without need, causing a performance degradation. Fixes: 70fe3d980f5f ("powerpc: Restore FPU/VEC/VSX if previously used") Cc: stable@vger.kernel.org # v4.6+ Signed-off-by: Breno Leitao Signed-off-by: Gustavo Romero Acked-by: Anton Blanchard Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/process.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/powerpc/kernel/process.c') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index baae104b16c7..a9435397eab8 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1666,6 +1666,7 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp) #ifdef CONFIG_VSX current->thread.used_vsr = 0; #endif + current->thread.load_fp = 0; memset(¤t->thread.fp_state, 0, sizeof(current->thread.fp_state)); current->thread.fp_save_area = NULL; #ifdef CONFIG_ALTIVEC @@ -1674,6 +1675,7 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp) current->thread.vr_save_area = NULL; current->thread.vrsave = 0; current->thread.used_vr = 0; + current->thread.load_vec = 0; #endif /* CONFIG_ALTIVEC */ #ifdef CONFIG_SPE memset(current->thread.evr, 0, sizeof(current->thread.evr)); -- cgit From 7f22ced4377628074e2ac25f41a88f98eb3b03f1 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Mon, 5 Jun 2017 11:40:59 -0300 Subject: powerpc/kernel: Initialize load_tm on task creation Currently tsk->thread.load_tm is not initialized in the task creation and can contain garbage on a new task. This is an undesired behaviour, since it affects the timing to enable and disable the transactional memory laziness (disabling and enabling the MSR TM bit, which affects TM reclaim and recheckpoint in the scheduling process). Fixes: 5d176f751ee3 ("powerpc: tm: Enable transactional memory (TM) lazily for userspace") Cc: stable@vger.kernel.org # v4.9+ Signed-off-by: Breno Leitao Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/process.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/powerpc/kernel/process.c') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index a9435397eab8..2ad725ef4368 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1687,6 +1687,7 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp) current->thread.tm_tfhar = 0; current->thread.tm_texasr = 0; current->thread.tm_tfiar = 0; + current->thread.load_tm = 0; #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ } EXPORT_SYMBOL(start_thread); -- cgit