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When an interrupt is taken, the SRR registers are set to return to where it left off. Unless they are modified in the meantime, or the return address or MSR are modified, there is no need to reload these registers when returning from interrupt. Introduce per-CPU flags that track the validity of SRR and HSRR registers. These are cleared when returning from interrupt, when using the registers for something else (e.g., OPAL calls), when adjusting the return address or MSR of a context, and when context switching (which changes the return address and MSR). This improves the performance of interrupt returns. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Fold in fixup patch from Nick] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com
41 lines
1.1 KiB
C
41 lines
1.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* livepatch.h - powerpc-specific Kernel Live Patching Core
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*
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* Copyright (C) 2015-2016, SUSE, IBM Corp.
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*/
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#ifndef _ASM_POWERPC_LIVEPATCH_H
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#define _ASM_POWERPC_LIVEPATCH_H
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#include <linux/sched/task_stack.h>
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#ifdef CONFIG_LIVEPATCH
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static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip)
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{
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struct pt_regs *regs = ftrace_get_regs(fregs);
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regs_set_return_ip(regs, ip);
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}
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#define klp_get_ftrace_location klp_get_ftrace_location
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static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
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{
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/*
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* Live patch works only with -mprofile-kernel on PPC. In this case,
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* the ftrace location is always within the first 16 bytes.
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*/
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return ftrace_location_range(faddr, faddr + 16);
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}
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static inline void klp_init_thread_info(struct task_struct *p)
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{
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/* + 1 to account for STACK_END_MAGIC */
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task_thread_info(p)->livepatch_sp = end_of_stack(p) + 1;
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}
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#else
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static inline void klp_init_thread_info(struct task_struct *p) { }
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#endif /* CONFIG_LIVEPATCH */
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#endif /* _ASM_POWERPC_LIVEPATCH_H */
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