6.9-stable review patch. If anyone has any objections, please let me know.
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From: Benjamin Gray bgray@linux.ibm.com
[ Upstream commit 75171f06c4507c3b6b5a69d793879fb20d108bb1 ]
Add capability to make the DEXCR act as a per-process SPR.
We do not yet have an interface for changing the values per task. We also expect the kernel to use a single DEXCR value across all tasks while in privileged state, so there is no need to synchronize after changing it (the userspace aspects will synchronize upon returning to userspace).
Signed-off-by: Benjamin Gray bgray@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/20240417112325.728010-3-bgray@linux.ibm.com Stable-dep-of: bbd99922d0f4 ("powerpc/dexcr: Reset DEXCR value across exec") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/processor.h | 1 + arch/powerpc/kernel/process.c | 10 ++++++++++ arch/powerpc/kernel/ptrace/ptrace-view.c | 7 +------ 3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index b2c51d337e60c..882e31296ea6b 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -260,6 +260,7 @@ struct thread_struct { unsigned long sier2; unsigned long sier3; unsigned long hashkeyr; + unsigned long dexcr;
#endif }; diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 9452a54d356c9..d482c3fd81d7a 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1185,6 +1185,9 @@ static inline void save_sprs(struct thread_struct *t)
if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE)) t->hashkeyr = mfspr(SPRN_HASHKEYR); + + if (cpu_has_feature(CPU_FTR_ARCH_31)) + t->dexcr = mfspr(SPRN_DEXCR); #endif }
@@ -1267,6 +1270,10 @@ static inline void restore_sprs(struct thread_struct *old_thread, if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE) && old_thread->hashkeyr != new_thread->hashkeyr) mtspr(SPRN_HASHKEYR, new_thread->hashkeyr); + + if (cpu_has_feature(CPU_FTR_ARCH_31) && + old_thread->dexcr != new_thread->dexcr) + mtspr(SPRN_DEXCR, new_thread->dexcr); #endif
} @@ -1878,6 +1885,9 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) #ifdef CONFIG_PPC_BOOK3S_64 if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE)) p->thread.hashkeyr = current->thread.hashkeyr; + + if (cpu_has_feature(CPU_FTR_ARCH_31)) + p->thread.dexcr = mfspr(SPRN_DEXCR); #endif return 0; } diff --git a/arch/powerpc/kernel/ptrace/ptrace-view.c b/arch/powerpc/kernel/ptrace/ptrace-view.c index 584cf5c3df509..c1819e0a66842 100644 --- a/arch/powerpc/kernel/ptrace/ptrace-view.c +++ b/arch/powerpc/kernel/ptrace/ptrace-view.c @@ -469,12 +469,7 @@ static int dexcr_get(struct task_struct *target, const struct user_regset *regse if (!cpu_has_feature(CPU_FTR_ARCH_31)) return -ENODEV;
- /* - * The DEXCR is currently static across all CPUs, so we don't - * store the target's value anywhere, but the static value - * will also be correct. - */ - membuf_store(&to, (u64)lower_32_bits(DEXCR_INIT)); + membuf_store(&to, (u64)lower_32_bits(target->thread.dexcr));
/* * Technically the HDEXCR is per-cpu, but a hypervisor can't reasonably