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SubjectRe: [RFC PATCH 3/4] powerpc: Optimize register usage for dear register
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Le 26/07/2021 à 16:30, sxwjean@me.com a écrit :
> From: Xiongwei Song <sxwjean@gmail.com>
>
> Create an anonymous union for dar and dear regsiters, we can reference
> dear to get the effective address when CONFIG_4xx=y or CONFIG_BOOKE=y.
> Otherwise, reference dar. This makes code more clear.

Same comment here as for patch 1.


>
> Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
> ---
> arch/powerpc/include/asm/ptrace.h | 5 ++++-
> arch/powerpc/include/uapi/asm/ptrace.h | 5 ++++-
> arch/powerpc/kernel/process.c | 2 +-
> arch/powerpc/kernel/ptrace/ptrace.c | 2 ++
> arch/powerpc/kernel/traps.c | 5 ++++-
> arch/powerpc/mm/fault.c | 2 +-
> 6 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
> index c252d04b1206..fa725e3238c2 100644
> --- a/arch/powerpc/include/asm/ptrace.h
> +++ b/arch/powerpc/include/asm/ptrace.h
> @@ -43,7 +43,10 @@ struct pt_regs
> unsigned long mq;
> #endif
> unsigned long trap;
> - unsigned long dar;
> + union {
> + unsigned long dar;
> + unsigned long dear;
> + };
> union {
> unsigned long dsisr;
> unsigned long esr;
> diff --git a/arch/powerpc/include/uapi/asm/ptrace.h b/arch/powerpc/include/uapi/asm/ptrace.h
> index e357288b5f34..9ae150fb4c4b 100644
> --- a/arch/powerpc/include/uapi/asm/ptrace.h
> +++ b/arch/powerpc/include/uapi/asm/ptrace.h
> @@ -52,7 +52,10 @@ struct pt_regs
> unsigned long trap; /* Reason for being here */
> /* N.B. for critical exceptions on 4xx, the dar and dsisr
> fields are overloaded to hold srr0 and srr1. */
> - unsigned long dar; /* Fault registers */
> + union {
> + unsigned long dar; /* Fault registers */
> + unsigned long dear;
> + };
> union {
> unsigned long dsisr; /* on Book-S used for DSISR */
> unsigned long esr; /* on 4xx/Book-E used for ESR */
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index f74af8f9133c..50436b52c213 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1499,7 +1499,7 @@ static void __show_regs(struct pt_regs *regs)
> trap == INTERRUPT_DATA_STORAGE ||
> trap == INTERRUPT_ALIGNMENT) {
> if (IS_ENABLED(CONFIG_4xx) || IS_ENABLED(CONFIG_BOOKE))
> - pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar, regs->esr);
> + pr_cont("DEAR: "REG" ESR: "REG" ", regs->dear, regs->esr);
> else
> pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
> }
> diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
> index 00789ad2c4a3..969dca8b0718 100644
> --- a/arch/powerpc/kernel/ptrace/ptrace.c
> +++ b/arch/powerpc/kernel/ptrace/ptrace.c
> @@ -373,6 +373,8 @@ void __init pt_regs_check(void)
> offsetof(struct user_pt_regs, trap));
> BUILD_BUG_ON(offsetof(struct pt_regs, dar) !=
> offsetof(struct user_pt_regs, dar));
> + BUILD_BUG_ON(offsetof(struct pt_regs, dear) !=
> + offsetof(struct user_pt_regs, dear));
> BUILD_BUG_ON(offsetof(struct pt_regs, dsisr) !=
> offsetof(struct user_pt_regs, dsisr));
> BUILD_BUG_ON(offsetof(struct pt_regs, esr) !=
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 2164f5705a0b..0796630d3d23 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -1609,7 +1609,10 @@ DEFINE_INTERRUPT_HANDLER(alignment_exception)
> }
> bad:
> if (user_mode(regs))
> - _exception(sig, regs, code, regs->dar);
> + if (IS_ENABLED(CONFIG_4xx) || IS_ENABLED(CONFIG_BOOKE))
> + _exception(sig, regs, code, regs->dear);
> + else
> + _exception(sig, regs, code, regs->dar);
> else
> bad_page_fault(regs, sig);
> }
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 62953d4e7c93..3db6b39a1178 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -542,7 +542,7 @@ static __always_inline void __do_page_fault(struct pt_regs *regs)
> long err;
>
> if (IS_ENABLED(CONFIG_4xx) || IS_ENABLED(CONFIG_BOOKE))
> - err = ___do_page_fault(regs, regs->dar, regs->esr);
> + err = ___do_page_fault(regs, regs->dear, regs->esr);
> else
> err = ___do_page_fault(regs, regs->dar, regs->dsisr);
>
>

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