by Palmer Dabbelt

[permalink] [raw]

Subject: Re: [PATCH v5 2/9] RISC-V: Add early ioremap support

On Wed, 12 Aug 2020 16:47:51 PDT (-0700), Atish Patra wrote:
> UEFI uses early IO or memory mappings for runtime services before
> normal ioremap() is usable. Add the necessary fixmap bindings and
> pmd mappings for generic ioremap support to work.
>
> Signed-off-by: Atish Patra <[email protected]>
> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/include/asm/Kbuild | 1 +
> arch/riscv/include/asm/fixmap.h | 13 +++++++++++++
> arch/riscv/include/asm/io.h | 1 +
> arch/riscv/kernel/setup.c | 1 +
> arch/riscv/mm/init.c | 33 +++++++++++++++++++++++++++++++++
> 6 files changed, 50 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 7b5905529146..15597f5f504f 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -37,6 +37,7 @@ config RISCV
> select GENERIC_ARCH_TOPOLOGY if SMP
> select GENERIC_ATOMIC64 if !64BIT
> select GENERIC_CLOCKEVENTS
> + select GENERIC_EARLY_IOREMAP
> select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
> select GENERIC_IOREMAP
> select GENERIC_IRQ_MULTI_HANDLER
> diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
> index 3d9410bb4de0..59dd7be55005 100644
> --- a/arch/riscv/include/asm/Kbuild
> +++ b/arch/riscv/include/asm/Kbuild
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0
> +generic-y += early_ioremap.h
> generic-y += extable.h
> generic-y += flat.h
> generic-y += kvm_para.h
> diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> index 11613f38228a..54cbf07fb4e9 100644
> --- a/arch/riscv/include/asm/fixmap.h
> +++ b/arch/riscv/include/asm/fixmap.h
> @@ -27,6 +27,19 @@ enum fixed_addresses {
> FIX_TEXT_POKE1,
> FIX_TEXT_POKE0,
> FIX_EARLYCON_MEM_BASE,
> +
> + __end_of_permanent_fixed_addresses,
> + /*
> + * Temporary boot-time mappings, used by early_ioremap(),
> + * before ioremap() is functional.
> + */
> +#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE)
> +#define FIX_BTMAPS_SLOTS 7
> +#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> +
> + FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
> + FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
> +
> __end_of_fixed_addresses
> };
>
> diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
> index 3835c3295dc5..c025a746a148 100644
> --- a/arch/riscv/include/asm/io.h
> +++ b/arch/riscv/include/asm/io.h
> @@ -14,6 +14,7 @@
> #include <linux/types.h>
> #include <linux/pgtable.h>
> #include <asm/mmiowb.h>
> +#include <asm/early_ioremap.h>
>
> /*
> * MMIO access functions are separated out to break dependency cycles
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 6a0ee2405813..c71788e6aff4 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -72,6 +72,7 @@ void __init setup_arch(char **cmdline_p)
>
> *cmdline_p = boot_command_line;
>
> + early_ioremap_setup();
> parse_early_param();
>
> setup_bootmem();
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 2b651f63f5c4..b75ebe8e7a92 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -403,6 +403,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> uintptr_t load_pa = (uintptr_t)(&_start);
> uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
> uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
> +#ifndef __PAGETABLE_PMD_FOLDED
> + pmd_t fix_bmap_spmd, fix_bmap_epmd;
> +#endif
>
> va_pa_offset = PAGE_OFFSET - load_pa;
> pfn_base = PFN_DOWN(load_pa);
> @@ -456,6 +459,36 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL);
> dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE - 1));
> dtb_early_pa = dtb_pa;
> +
> + /*
> + * Bootime fixmap only can handle PMD_SIZE mapping. Thus, boot-ioremap
> + * range can not span multiple pmds.
> + */
> + BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
> + != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
> +
> +#ifndef __PAGETABLE_PMD_FOLDED
> + /*
> + * Early ioremap fixmap is already created as it lies within first 2MB
> + * of fixmap region. We always map PMD_SIZE. Thus, both FIX_BTMAP_END
> + * FIX_BTMAP_BEGIN should lie in the same pmd. Verify that and warn
> + * the user if not.
> + */
> + fix_bmap_spmd = fixmap_pmd[pmd_index(__fix_to_virt(FIX_BTMAP_BEGIN))];
> + fix_bmap_epmd = fixmap_pmd[pmd_index(__fix_to_virt(FIX_BTMAP_END))];
> + if (pmd_val(fix_bmap_spmd) != pmd_val(fix_bmap_epmd)) {
> + WARN_ON(1);
> + pr_warn("fixmap btmap start [%08lx] != end [%08lx]\n",
> + pmd_val(fix_bmap_spmd), pmd_val(fix_bmap_epmd));
> + pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
> + fix_to_virt(FIX_BTMAP_BEGIN));
> + pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n",
> + fix_to_virt(FIX_BTMAP_END));
> +
> + pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END);
> + pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN);
> + }
> +#endif
> }
>
> static void __init setup_vm_final(void)

Reviewed-by: Palmer Dabbelt <[email protected]>