Messages in this thread Patch in this message | | | From | ira.weiny@intel ... | Subject | [RFC PATCH 2/5] entry: Add calls for save/restore auxiliary pt_regs | Date | Fri, 5 Aug 2022 10:30:06 -0700 |
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From: Ira Weiny <ira.weiny@intel.com>
Some architectures have auxiliary pt_regs space available to store information on the stack during exceptions. This information is easier to obtain and store within C code rather than in arch specific assembly.
Define empty calls to architecture specific save and restore auxiliary pt_regs functions. Call these functions on generic entry/exit.
NOTE: Due to the split nature of the Xen exit code irqentry_exit_cond_resched() requires an unbalanced call to arch_restore_aux_pt_regs().
Cc: Rik van Riel <riel@surriel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
--- Forward ported from PKS series https://lore.kernel.org/lkml/20220419170649.1022246-20-ira.weiny@intel.com/ --- include/linux/entry-common.h | 8 ++++++++ kernel/entry/common.c | 16 ++++++++++++++-- 2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 976cce7cf803..1c09ba64ad28 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -79,6 +79,14 @@ static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs); static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {} #endif +#ifndef arch_save_aux_pt_regs +static inline void arch_save_aux_pt_regs(struct pt_regs *regs) { } +#endif + +#ifndef arch_restore_aux_pt_regs +static inline void arch_restore_aux_pt_regs(struct pt_regs *regs) { } +#endif + /** * enter_from_user_mode - Establish state when coming from user mode * diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 8c0f334c4b75..a70a0f314aee 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -317,7 +317,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) if (user_mode(regs)) { irqentry_enter_from_user_mode(regs); - return ret; + goto aux_save; } /* @@ -356,7 +356,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) instrumentation_end(); ret.exit_rcu = true; - return ret; + goto aux_save; } /* @@ -371,6 +371,11 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) trace_hardirqs_off_finish(); instrumentation_end(); +aux_save: + instrumentation_begin(); + arch_save_aux_pt_regs(regs); + instrumentation_end(); + return ret; } @@ -401,6 +406,7 @@ void dynamic_irqentry_exit_cond_resched(void) void irqentry_exit_cond_resched(struct pt_regs *regs) { + arch_restore_aux_pt_regs(regs); irqentry_exit_cond_resched_internal(); } @@ -408,6 +414,10 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) { lockdep_assert_irqs_disabled(); + instrumentation_begin(); + arch_restore_aux_pt_regs(regs); + instrumentation_end(); + /* Check whether this returns to user mode */ if (user_mode(regs)) { irqentry_exit_to_user_mode(regs); @@ -459,6 +469,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) instrumentation_begin(); trace_hardirqs_off_finish(); ftrace_nmi_enter(); + arch_save_aux_pt_regs(regs); instrumentation_end(); return irq_state; @@ -467,6 +478,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state) { instrumentation_begin(); + arch_restore_aux_pt_regs(regs); ftrace_nmi_exit(); if (irq_state.lockdep) { trace_hardirqs_on_prepare(); -- 2.35.3
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