[PATCH 14/19] powerpc: Add ppc_strict_facility_enable boot option
From: Anton Blanchard <hidden>
Date: 2015-10-29 01:07:07
Subsystem:
documentation, linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Jonathan Corbet, Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
Add a boot option that strictly manages the MSR unavailable bits. This catches kernel uses of FP/Altivec/SPE that would otherwise corrupt user state. Signed-off-by: Anton Blanchard <redacted> --- Documentation/kernel-parameters.txt | 6 ++++++ arch/powerpc/include/asm/reg.h | 9 +++++++++ arch/powerpc/include/asm/switch_to.h | 24 +++++++++++++++++++----- arch/powerpc/kernel/process.c | 17 +++++++++++++++-- 4 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22a4b68..f535a02 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt@@ -2939,6 +2939,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. may be specified. Format: <port>,<port>.... + ppc_strict_facility_enable + [PPC] This option catches any kernel floating point, + Altivec, VSX and SPE outside of regions specifically + allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). + There is some performance impact when enabling this. + print-fatal-signals= [KNL] debug: print fatal signals
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 987dac0..eb2986e 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h@@ -1214,6 +1214,15 @@ static inline void mtmsr_isync(unsigned long val) : "r" ((unsigned long)(v)) \ : "memory") +extern void msr_check_and_set(unsigned long bits); +extern bool strict_msr_control; +extern void __msr_check_and_clear(unsigned long bits); +static inline void msr_check_and_clear(unsigned long bits) +{ + if (strict_msr_control) + __msr_check_and_clear(bits); +} + static inline unsigned long mfvtb (void) { #ifdef CONFIG_PPC_BOOK3S_64
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 438502f..9414dcb 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h@@ -4,6 +4,8 @@ #ifndef _ASM_POWERPC_SWITCH_TO_H #define _ASM_POWERPC_SWITCH_TO_H +#include <asm/reg.h> + struct thread_struct; struct task_struct; struct pt_regs;
@@ -26,15 +28,15 @@ extern void enable_kernel_spe(void); extern void load_up_spe(struct task_struct *); extern void switch_booke_debug_regs(struct debug_reg *new_debug); -static inline void disable_kernel_fp(void) { } -static inline void disable_kernel_altivec(void) { } -static inline void disable_kernel_spe(void) { } -static inline void disable_kernel_vsx(void) { } - #ifdef CONFIG_PPC_FPU extern void flush_fp_to_thread(struct task_struct *); extern void giveup_fpu(struct task_struct *); extern void __giveup_fpu(struct task_struct *); +static inline void disable_kernel_fp(void) +{ + msr_check_and_clear(MSR_FP); +} + #else static inline void flush_fp_to_thread(struct task_struct *t) { } static inline void giveup_fpu(struct task_struct *t) { }
@@ -45,6 +47,10 @@ static inline void __giveup_fpu(struct task_struct *t) { } extern void flush_altivec_to_thread(struct task_struct *); extern void giveup_altivec(struct task_struct *); extern void __giveup_altivec(struct task_struct *); +static inline void disable_kernel_altivec(void) +{ + msr_check_and_clear(MSR_VEC); +} #else static inline void flush_altivec_to_thread(struct task_struct *t) { } static inline void giveup_altivec(struct task_struct *t) { }
@@ -53,6 +59,10 @@ static inline void __giveup_altivec(struct task_struct *t) { } #ifdef CONFIG_VSX extern void flush_vsx_to_thread(struct task_struct *); +static inline void disable_kernel_vsx(void) +{ + msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX); +} #else static inline void flush_vsx_to_thread(struct task_struct *t) {
@@ -63,6 +73,10 @@ static inline void flush_vsx_to_thread(struct task_struct *t) extern void flush_spe_to_thread(struct task_struct *); extern void giveup_spe(struct task_struct *); extern void __giveup_spe(struct task_struct *); +static inline void disable_kernel_spe(void) +{ + msr_check_and_clear(MSR_SPE); +} #else static inline void flush_spe_to_thread(struct task_struct *t) { } static inline void giveup_spe(struct task_struct *t) { }
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 5cdd35c..1eafcee 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c@@ -87,7 +87,19 @@ static void check_if_tm_restore_required(struct task_struct *tsk) static inline void check_if_tm_restore_required(struct task_struct *tsk) { } #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ -static void msr_check_and_set(unsigned long bits) +bool strict_msr_control; +EXPORT_SYMBOL(strict_msr_control); + +static int __init enable_strict_msr_control(char *str) +{ + strict_msr_control = true; + pr_info("Enabling strict facility control\n"); + + return 0; +} +early_param("ppc_strict_facility_enable", enable_strict_msr_control); + +void msr_check_and_set(unsigned long bits) { unsigned long oldmsr = mfmsr(); unsigned long newmsr;
@@ -103,7 +115,7 @@ static void msr_check_and_set(unsigned long bits) mtmsr_isync(newmsr); } -static void msr_check_and_clear(unsigned long bits) +void __msr_check_and_clear(unsigned long bits) { unsigned long oldmsr = mfmsr(); unsigned long newmsr;
@@ -118,6 +130,7 @@ static void msr_check_and_clear(unsigned long bits) if (oldmsr != newmsr) mtmsr_isync(newmsr); } +EXPORT_SYMBOL(__msr_check_and_clear); #ifdef CONFIG_PPC_FPU void giveup_fpu(struct task_struct *tsk)
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2.5.0