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Subject: Re: [RFC PATCH 04/10] powerpc/fsl_booke/32: introduce
 create_tlb_entry() helper
To:     Jason Yan <yanaijie@huawei.com>, mpe@ellerman.id.au,
        linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com,
        benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com,
        keescook@chromium.org, kernel-hardening@lists.openwall.com
Cc:     linux-kernel@vger.kernel.org, wangkefeng.wang@huawei.com,
        yebin10@huawei.com, thunder.leizhen@huawei.com,
        jingxiangfeng@huawei.com, fanchengyang@huawei.com
References: <20190717080621.40424-1-yanaijie@huawei.com>
 <20190717080621.40424-5-yanaijie@huawei.com>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <4e6c468d-287b-4bba-675c-8b3f73456500@c-s.fr>
Date:   Mon, 29 Jul 2019 13:05:04 +0200
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Le 17/07/2019 à 10:06, Jason Yan a écrit :
> Add a new helper create_tlb_entry() to create a tlb entry by the virtual
> and physical address. This is a preparation to support boot kernel at a
> randomized address.
> 
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> Cc: Diana Craciun <diana.craciun@nxp.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Kees Cook <keescook@chromium.org>
> ---
>   arch/powerpc/kernel/head_fsl_booke.S | 30 ++++++++++++++++++++++++++++
>   arch/powerpc/mm/mmu_decl.h           |  1 +
>   2 files changed, 31 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
> index adf0505dbe02..a57d44638031 100644
> --- a/arch/powerpc/kernel/head_fsl_booke.S
> +++ b/arch/powerpc/kernel/head_fsl_booke.S
> @@ -1114,6 +1114,36 @@ __secondary_hold_acknowledge:
>   	.long	-1
>   #endif
>   
> +/*
> + * Create a 64M tlb by address and entry
> + * r3/r4 - physical address
> + * r5 - virtual address
> + * r6 - entry
> + */
> +_GLOBAL(create_tlb_entry)
> +	lis     r7,0x1000               /* Set MAS0(TLBSEL) = 1 */
> +	rlwimi  r7,r6,16,4,15           /* Setup MAS0 = TLBSEL | ESEL(r6) */
> +	mtspr   SPRN_MAS0,r7            /* Write MAS0 */
> +
> +	lis     r6,(MAS1_VALID|MAS1_IPROT)@h
> +	ori     r6,r6,(MAS1_TSIZE(BOOK3E_PAGESZ_64M))@l
> +	mtspr   SPRN_MAS1,r6            /* Write MAS1 */
> +
> +	lis     r6,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@h
> +	ori     r6,r6,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@l
> +	and     r6,r6,r5
> +	ori	r6,r6,MAS2_M@l
> +	mtspr   SPRN_MAS2,r6            /* Write MAS2(EPN) */
> +
> +	mr      r8,r4
> +	ori     r8,r8,(MAS3_SW|MAS3_SR|MAS3_SX)

Could drop the mr r8, r4 and do:

ori     r8,r4,(MAS3_SW|MAS3_SR|MAS3_SX)

> +	mtspr   SPRN_MAS3,r8            /* Write MAS3(RPN) */
> +
> +	tlbwe                           /* Write TLB */
> +	isync
> +	sync
> +	blr
> +
>   /*
>    * Create a tlb entry with the same effective and physical address as
>    * the tlb entry used by the current running code. But set the TS to 1.
> diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
> index 32c1a191c28a..d7737cf97cee 100644
> --- a/arch/powerpc/mm/mmu_decl.h
> +++ b/arch/powerpc/mm/mmu_decl.h
> @@ -142,6 +142,7 @@ extern unsigned long calc_cam_sz(unsigned long ram, unsigned long virt,
>   extern void adjust_total_lowmem(void);
>   extern int switch_to_as1(void);
>   extern void restore_to_as0(int esel, int offset, void *dt_ptr, int bootcpu);
> +extern void create_tlb_entry(phys_addr_t phys, unsigned long virt, int entry);

Please please do not add new declarations with the useless 'extern' 
keyword. See checkpatch report: 
https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/8124//artifact/linux/checkpatch.log

>   #endif
>   extern void loadcam_entry(unsigned int index);
>   extern void loadcam_multi(int first_idx, int num, int tmp_idx);
>