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    Subject[PATCH v5 36/75] x86/head/64: Move early exception dispatch to C code
    Date
    From: Joerg Roedel <jroedel@suse.de>

    Move the assembly coded dispatch between page-faults and all other
    exceptions to C code to make it easier to maintain and extend.

    Also change the return-type of early_make_pgtable() to bool and make it
    static.

    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    ---
    arch/x86/include/asm/pgtable.h | 2 +-
    arch/x86/include/asm/setup.h | 1 -
    arch/x86/kernel/head64.c | 19 +++++++++++++++----
    arch/x86/kernel/head_64.S | 11 +----------
    4 files changed, 17 insertions(+), 16 deletions(-)

    diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
    index b836138ce852..7b8f2127de37 100644
    --- a/arch/x86/include/asm/pgtable.h
    +++ b/arch/x86/include/asm/pgtable.h
    @@ -28,7 +28,7 @@
    #include <asm-generic/pgtable_uffd.h>

    extern pgd_t early_top_pgt[PTRS_PER_PGD];
    -int __init __early_make_pgtable(unsigned long address, pmdval_t pmd);
    +bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd);

    void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm);
    void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
    diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
    index 5c09f50ecf1c..78bdc0f686fb 100644
    --- a/arch/x86/include/asm/setup.h
    +++ b/arch/x86/include/asm/setup.h
    @@ -49,7 +49,6 @@ extern void i386_reserve_resources(void);
    extern unsigned long __startup_64(unsigned long physaddr, struct boot_params *bp);
    extern unsigned long __startup_secondary_64(void);
    extern void startup_64_setup_env(unsigned long physbase);
    -extern int early_make_pgtable(unsigned long address);
    extern void early_idt_setup_early_handler(unsigned long physaddr);
    extern void early_load_idt(void);

    diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
    index 096b09d06d1c..41514ec1e6f0 100644
    --- a/arch/x86/kernel/head64.c
    +++ b/arch/x86/kernel/head64.c
    @@ -37,6 +37,8 @@
    #include <asm/kasan.h>
    #include <asm/fixmap.h>
    #include <asm/realmode.h>
    +#include <asm/extable.h>
    +#include <asm/trapnr.h>

    /*
    * Manage page tables very early on.
    @@ -314,7 +316,7 @@ static void __init reset_early_page_tables(void)
    }

    /* Create a new PMD entry */
    -int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
    +bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
    {
    unsigned long physaddr = address - __PAGE_OFFSET;
    pgdval_t pgd, *pgd_p;
    @@ -324,7 +326,7 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)

    /* Invalid address or early pgt is done ? */
    if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
    - return -1;
    + return false;

    again:
    pgd_p = &early_top_pgt[pgd_index(address)].pgd;
    @@ -381,10 +383,10 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
    }
    pmd_p[pmd_index(address)] = pmd;

    - return 0;
    + return true;
    }

    -int __init early_make_pgtable(unsigned long address)
    +static bool __init early_make_pgtable(unsigned long address)
    {
    unsigned long physaddr = address - __PAGE_OFFSET;
    pmdval_t pmd;
    @@ -394,6 +396,15 @@ int __init early_make_pgtable(unsigned long address)
    return __early_make_pgtable(address, pmd);
    }

    +void __init do_early_exception(struct pt_regs *regs, int trapnr)
    +{
    + if (trapnr == X86_TRAP_PF &&
    + early_make_pgtable(native_read_cr2()))
    + return;
    +
    + early_fixup_exception(regs, trapnr);
    +}
    +
    /* Don't add a printk in there. printk relies on the PDA which is not initialized
    yet. */
    static void __init clear_bss(void)
    diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
    index 28de83fecda3..08412f308de3 100644
    --- a/arch/x86/kernel/head_64.S
    +++ b/arch/x86/kernel/head_64.S
    @@ -349,18 +349,9 @@ SYM_CODE_START_LOCAL(early_idt_handler_common)
    pushq %r15 /* pt_regs->r15 */
    UNWIND_HINT_REGS

    - cmpq $14,%rsi /* Page fault? */
    - jnz 10f
    - GET_CR2_INTO(%rdi) /* can clobber %rax if pv */
    - call early_make_pgtable
    - andl %eax,%eax
    - jz 20f /* All good */
    -
    -10:
    movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */
    - call early_fixup_exception
    + call do_early_exception

    -20:
    decl early_recursion_flag(%rip)
    jmp restore_regs_and_return_to_kernel
    SYM_CODE_END(early_idt_handler_common)
    --
    2.27.0
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