linux-kernel - Re: [RFC PATCH -next V3 6/6] arm64: add cow to machine check safe

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Message-ID: <a58b640d-e12a-7b9d-2ab0-d95a3ae6950e@arm.com>
Date:   Tue, 12 Apr 2022 17:39:04 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Tong Tiangen <tongtiangen@...wei.com>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Kefeng Wang <wangkefeng.wang@...wei.com>,
        Xie XiuQi <xiexiuqi@...wei.com>
Subject: Re: [RFC PATCH -next V3 6/6] arm64: add cow to machine check safe

On 12/04/2022 8:25 am, Tong Tiangen wrote:
[...]
> +100:	ldp	x2, x3, [x1]
> +101:	ldp	x4, x5, [x1, #16]
> +102:	ldp	x6, x7, [x1, #32]
> +103:	ldp	x8, x9, [x1, #48]
> +104:	ldp	x10, x11, [x1, #64]
> +105:	ldp	x12, x13, [x1, #80]
> +106:	ldp	x14, x15, [x1, #96]
> +107:	ldp	x16, x17, [x1, #112]
> +
> +	add	x0, x0, #256
> +	add	x1, x1, #128
> +1:
> +	tst	x0, #(PAGE_SIZE - 1)
> +
> +alternative_if ARM64_HAS_NO_HW_PREFETCH
> +	prfm	pldl1strm, [x1, #384]
> +alternative_else_nop_endif
> +
> +	stnp	x2, x3, [x0, #-256]
> +200:	ldp	x2, x3, [x1]
> +	stnp	x4, x5, [x0, #16 - 256]
> +201:	ldp	x4, x5, [x1, #16]
> +	stnp	x6, x7, [x0, #32 - 256]
> +202:	ldp	x6, x7, [x1, #32]
> +	stnp	x8, x9, [x0, #48 - 256]
> +203:	ldp	x8, x9, [x1, #48]
> +	stnp	x10, x11, [x0, #64 - 256]
> +204:	ldp	x10, x11, [x1, #64]
> +	stnp	x12, x13, [x0, #80 - 256]
> +205:	ldp	x12, x13, [x1, #80]
> +	stnp	x14, x15, [x0, #96 - 256]
> +206:	ldp	x14, x15, [x1, #96]
> +	stnp	x16, x17, [x0, #112 - 256]
> +207:	ldp	x16, x17, [x1, #112]
> +
> +	add	x0, x0, #128
> +	add	x1, x1, #128
> +
> +	b.ne	1b
> +
> +	stnp	x2, x3, [x0, #-256]
> +	stnp	x4, x5, [x0, #16 - 256]
> +	stnp	x6, x7, [x0, #32 - 256]
> +	stnp	x8, x9, [x0, #48 - 256]
> +	stnp	x10, x11, [x0, #64 - 256]
> +	stnp	x12, x13, [x0, #80 - 256]
> +	stnp	x14, x15, [x0, #96 - 256]
> +	stnp	x16, x17, [x0, #112 - 256]
> +
> +300:	ret
> +
> +_asm_extable_copy_page_mc 100b, 300b
> +_asm_extable_copy_page_mc 101b, 300b
> +_asm_extable_copy_page_mc 102b, 300b
> +_asm_extable_copy_page_mc 103b, 300b
> +_asm_extable_copy_page_mc 104b, 300b
> +_asm_extable_copy_page_mc 105b, 300b
> +_asm_extable_copy_page_mc 106b, 300b
> +_asm_extable_copy_page_mc 107b, 300b
> +_asm_extable_copy_page_mc 200b, 300b
> +_asm_extable_copy_page_mc 201b, 300b
> +_asm_extable_copy_page_mc 202b, 300b
> +_asm_extable_copy_page_mc 203b, 300b
> +_asm_extable_copy_page_mc 204b, 300b
> +_asm_extable_copy_page_mc 205b, 300b
> +_asm_extable_copy_page_mc 206b, 300b
> +_asm_extable_copy_page_mc 207b, 300b


Please add a USER_MC() macro to parallel the existing USER() one (we can 
worry about names and eventually consolidating things later), then use 
that to save all the label mess here.

Thanks,
Robin.