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Date:   Tue, 1 Jun 2021 13:21:05 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexandre Ghiti <alex@ghiti.fr>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: mm: init: Consolidate vars, functions
Message-ID: <YLaWseLdg5JYElVx@Ryzen-9-3900X.localdomain>
References: <20210516211556.43c00055@xhacker>
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In-Reply-To: <20210516211556.43c00055@xhacker>
Precedence: bulk

Hi Jisheng,

On Sun, May 16, 2021 at 09:15:56PM +0800, Jisheng Zhang wrote:
> From: Jisheng Zhang <jszhang@kernel.org>
> 
> Consolidate the following items in init.c
> 
> Staticize global vars as much as possible;
> Add __initdata mark if the global var isn't needed after init
> Add __init mark if the func isn't needed after init
> Add __ro_after_init if the global var is read only after init
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/include/asm/set_memory.h |  2 +-
>  arch/riscv/mm/init.c                | 36 +++++++++++++++--------------
>  2 files changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
> index 086f757e8ba3..9d4d455726d4 100644
> --- a/arch/riscv/include/asm/set_memory.h
> +++ b/arch/riscv/include/asm/set_memory.h
> @@ -27,7 +27,7 @@ static inline int set_memory_rw_nx(unsigned long addr, int numpages) { return 0;
>  #endif
>  
>  #if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
> -void protect_kernel_linear_mapping_text_rodata(void);
> +void __init protect_kernel_linear_mapping_text_rodata(void);
>  #else
>  static inline void protect_kernel_linear_mapping_text_rodata(void) {}
>  #endif
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 4c4c92ce0bb8..eac2d5c27b3e 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -53,7 +53,7 @@ struct pt_alloc_ops {
>  #endif
>  };
>  
> -static phys_addr_t dma32_phys_limit __ro_after_init;
> +static phys_addr_t dma32_phys_limit __initdata;
>  
>  static void __init zone_sizes_init(void)
>  {
> @@ -184,7 +184,7 @@ extern char _sdata[], _edata[];
>  #endif /* CONFIG_XIP_KERNEL */
>  
>  #ifdef CONFIG_MMU
> -static struct pt_alloc_ops _pt_ops __ro_after_init;
> +static struct pt_alloc_ops _pt_ops __initdata;
>  
>  #ifdef CONFIG_XIP_KERNEL
>  #define pt_ops (*(struct pt_alloc_ops *)XIP_FIXUP(&_pt_ops))
> @@ -200,13 +200,13 @@ EXPORT_SYMBOL(va_pa_offset);
>  #endif
>  /* Offset between kernel mapping virtual address and kernel load address */
>  #ifdef CONFIG_64BIT
> -unsigned long va_kernel_pa_offset;
> +unsigned long va_kernel_pa_offset __ro_after_init;
>  EXPORT_SYMBOL(va_kernel_pa_offset);
>  #endif
>  #ifdef CONFIG_XIP_KERNEL
>  #define va_kernel_pa_offset    (*((unsigned long *)XIP_FIXUP(&va_kernel_pa_offset)))
>  #endif
> -unsigned long va_kernel_xip_pa_offset;
> +unsigned long va_kernel_xip_pa_offset __ro_after_init;
>  EXPORT_SYMBOL(va_kernel_xip_pa_offset);
>  #ifdef CONFIG_XIP_KERNEL
>  #define va_kernel_xip_pa_offset        (*((unsigned long *)XIP_FIXUP(&va_kernel_xip_pa_offset)))
> @@ -216,7 +216,7 @@ EXPORT_SYMBOL(pfn_base);
>  
>  pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
>  pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> -pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
> +static pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
>  
>  pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
>  
> @@ -253,7 +253,7 @@ static inline pte_t *__init get_pte_virt_fixmap(phys_addr_t pa)
>  	return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
>  }
>  
> -static inline pte_t *get_pte_virt_late(phys_addr_t pa)
> +static inline pte_t *__init get_pte_virt_late(phys_addr_t pa)
>  {
>  	return (pte_t *) __va(pa);
>  }
> @@ -272,7 +272,7 @@ static inline phys_addr_t __init alloc_pte_fixmap(uintptr_t va)
>  	return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>  }
>  
> -static phys_addr_t alloc_pte_late(uintptr_t va)
> +static phys_addr_t __init alloc_pte_late(uintptr_t va)
>  {
>  	unsigned long vaddr;
>  
> @@ -296,10 +296,10 @@ static void __init create_pte_mapping(pte_t *ptep,
>  
>  #ifndef __PAGETABLE_PMD_FOLDED
>  
> -pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
> -pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
> -pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
> -pmd_t early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
> +static pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
> +static pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
> +static pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
> +static pmd_t early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
>  
>  #ifdef CONFIG_XIP_KERNEL
>  #define trampoline_pmd ((pmd_t *)XIP_FIXUP(trampoline_pmd))
> @@ -319,7 +319,7 @@ static pmd_t *__init get_pmd_virt_fixmap(phys_addr_t pa)
>  	return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
>  }
>  
> -static pmd_t *get_pmd_virt_late(phys_addr_t pa)
> +static pmd_t *__init get_pmd_virt_late(phys_addr_t pa)
>  {
>  	return (pmd_t *) __va(pa);
>  }
> @@ -336,7 +336,7 @@ static phys_addr_t __init alloc_pmd_fixmap(uintptr_t va)
>  	return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>  }
>  
> -static phys_addr_t alloc_pmd_late(uintptr_t va)
> +static phys_addr_t __init alloc_pmd_late(uintptr_t va)
>  {
>  	unsigned long vaddr;
>  
> @@ -454,14 +454,16 @@ asmlinkage void __init __copy_data(void)
>  #error "setup_vm() is called from head.S before relocate so it should not use absolute addressing."
>  #endif
>  
> -uintptr_t load_pa, load_sz;
> +static uintptr_t load_pa __initdata;

Making load_pa static causing clang built kernels to no longer boot,
hanging after just a few lines of output in the console:

https://github.com/ClangBuiltLinux/continuous-integration2/runs/2717606254?check_suite_focus=true

I am not sure why that would make a difference nor why GCC is okay with
it. If it is a clang bug, it appears to be there for a while, given that
it reproduces back to clang-11.

If I can provide any more information or help debug, let me know!

Cheers,
Nathan

> +static uintptr_t load_sz __initdata;
>  #ifdef CONFIG_XIP_KERNEL
>  #define load_pa        (*((uintptr_t *)XIP_FIXUP(&load_pa)))
>  #define load_sz        (*((uintptr_t *)XIP_FIXUP(&load_sz)))
>  #endif
>  
>  #ifdef CONFIG_XIP_KERNEL
> -uintptr_t xiprom, xiprom_sz;
> +static uintptr_t xiprom __inidata;
> +static uintptr_t xiprom_sz __initdata;
>  #define xiprom_sz      (*((uintptr_t *)XIP_FIXUP(&xiprom_sz)))
>  #define xiprom         (*((uintptr_t *)XIP_FIXUP(&xiprom)))
>  
> @@ -646,7 +648,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>  }
>  
>  #if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
> -void protect_kernel_linear_mapping_text_rodata(void)
> +void __init protect_kernel_linear_mapping_text_rodata(void)
>  {
>  	unsigned long text_start = (unsigned long)lm_alias(_start);
>  	unsigned long init_text_start = (unsigned long)lm_alias(__init_text_begin);
> @@ -858,7 +860,7 @@ static void __init reserve_crashkernel(void)
>   * reserved once we call early_init_fdt_scan_reserved_mem()
>   * later on.
>   */
> -static int elfcore_hdr_setup(struct reserved_mem *rmem)
> +static int __init elfcore_hdr_setup(struct reserved_mem *rmem)
>  {
>  	elfcorehdr_addr = rmem->base;
>  	elfcorehdr_size = rmem->size;
> -- 
> 2.31.0
>