Re: [PATCH 09/12] MIPS: mm: Pass scratch register through to iPTE_SW

From: James Hogan
Date: Fri Apr 15 2016 - 18:29:02 EST


On Fri, Apr 15, 2016 at 11:36:57AM +0100, Paul Burton wrote:
> Rather than hardcode a scratch register for the XPA case in iPTE_SW,
> pass one through from the work registers allocated by the caller. This
> allows for the XPA path to function correctly regardless of the work
> registers in use.

Looks good to me, although probably worth mentioning that the current
behaviour uses the $1 register, so this fixes another case of $1
clobbering.

Reviewed-by: James Hogan <james.hogan@xxxxxxxxxx>

Cheers
James

>
> Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
> ---
>
> arch/mips/mm/tlbex.c | 24 +++++++++++-------------
> 1 file changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
> index 004cd9f..d7a7b3d 100644
> --- a/arch/mips/mm/tlbex.c
> +++ b/arch/mips/mm/tlbex.c
> @@ -1526,14 +1526,12 @@ iPTE_LW(u32 **p, unsigned int pte, unsigned int ptr)
>
> static void
> iPTE_SW(u32 **p, struct uasm_reloc **r, unsigned int pte, unsigned int ptr,
> - unsigned int mode)
> + unsigned int mode, unsigned int scratch)
> {
> #ifdef CONFIG_PHYS_ADDR_T_64BIT
> unsigned int hwmode = mode & (_PAGE_VALID | _PAGE_DIRTY);
>
> if (config_enabled(CONFIG_XPA) && !cpu_has_64bits) {
> - const int scratch = 1; /* Our extra working register */
> -
> uasm_i_lui(p, scratch, (mode >> 16));
> uasm_i_or(p, pte, pte, scratch);
> } else
> @@ -1630,11 +1628,11 @@ build_pte_present(u32 **p, struct uasm_reloc **r,
> /* Make PTE valid, store result in PTR. */
> static void
> build_make_valid(u32 **p, struct uasm_reloc **r, unsigned int pte,
> - unsigned int ptr)
> + unsigned int ptr, unsigned int scratch)
> {
> unsigned int mode = _PAGE_VALID | _PAGE_ACCESSED;
>
> - iPTE_SW(p, r, pte, ptr, mode);
> + iPTE_SW(p, r, pte, ptr, mode, scratch);
> }
>
> /*
> @@ -1670,12 +1668,12 @@ build_pte_writable(u32 **p, struct uasm_reloc **r,
> */
> static void
> build_make_write(u32 **p, struct uasm_reloc **r, unsigned int pte,
> - unsigned int ptr)
> + unsigned int ptr, unsigned int scratch)
> {
> unsigned int mode = (_PAGE_ACCESSED | _PAGE_MODIFIED | _PAGE_VALID
> | _PAGE_DIRTY);
>
> - iPTE_SW(p, r, pte, ptr, mode);
> + iPTE_SW(p, r, pte, ptr, mode, scratch);
> }
>
> /*
> @@ -1780,7 +1778,7 @@ static void build_r3000_tlb_load_handler(void)
> build_r3000_tlbchange_handler_head(&p, K0, K1);
> build_pte_present(&p, &r, K0, K1, -1, label_nopage_tlbl);
> uasm_i_nop(&p); /* load delay */
> - build_make_valid(&p, &r, K0, K1);
> + build_make_valid(&p, &r, K0, K1, -1);
> build_r3000_tlb_reload_write(&p, &l, &r, K0, K1);
>
> uasm_l_nopage_tlbl(&l, p);
> @@ -1811,7 +1809,7 @@ static void build_r3000_tlb_store_handler(void)
> build_r3000_tlbchange_handler_head(&p, K0, K1);
> build_pte_writable(&p, &r, K0, K1, -1, label_nopage_tlbs);
> uasm_i_nop(&p); /* load delay */
> - build_make_write(&p, &r, K0, K1);
> + build_make_write(&p, &r, K0, K1, -1);
> build_r3000_tlb_reload_write(&p, &l, &r, K0, K1);
>
> uasm_l_nopage_tlbs(&l, p);
> @@ -1842,7 +1840,7 @@ static void build_r3000_tlb_modify_handler(void)
> build_r3000_tlbchange_handler_head(&p, K0, K1);
> build_pte_modifiable(&p, &r, K0, K1, -1, label_nopage_tlbm);
> uasm_i_nop(&p); /* load delay */
> - build_make_write(&p, &r, K0, K1);
> + build_make_write(&p, &r, K0, K1, -1);
> build_r3000_pte_reload_tlbwi(&p, K0, K1);
>
> uasm_l_nopage_tlbm(&l, p);
> @@ -2010,7 +2008,7 @@ static void build_r4000_tlb_load_handler(void)
> }
> uasm_l_tlbl_goaround1(&l, p);
> }
> - build_make_valid(&p, &r, wr.r1, wr.r2);
> + build_make_valid(&p, &r, wr.r1, wr.r2, wr.r3);
> build_r4000_tlbchange_handler_tail(&p, &l, &r, wr.r1, wr.r2);
>
> #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
> @@ -2124,7 +2122,7 @@ static void build_r4000_tlb_store_handler(void)
> build_pte_writable(&p, &r, wr.r1, wr.r2, wr.r3, label_nopage_tlbs);
> if (m4kc_tlbp_war())
> build_tlb_probe_entry(&p);
> - build_make_write(&p, &r, wr.r1, wr.r2);
> + build_make_write(&p, &r, wr.r1, wr.r2, wr.r3);
> build_r4000_tlbchange_handler_tail(&p, &l, &r, wr.r1, wr.r2);
>
> #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
> @@ -2180,7 +2178,7 @@ static void build_r4000_tlb_modify_handler(void)
> if (m4kc_tlbp_war())
> build_tlb_probe_entry(&p);
> /* Present and writable bits set, set accessed and dirty bits. */
> - build_make_write(&p, &r, wr.r1, wr.r2);
> + build_make_write(&p, &r, wr.r1, wr.r2, wr.r3);
> build_r4000_tlbchange_handler_tail(&p, &l, &r, wr.r1, wr.r2);
>
> #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
> --
> 2.8.0
>

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