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x86/head/64: Move early exception dispatch to C code

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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>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-36-joro@8bytes.org
This commit is contained in:
Joerg Roedel 2020-09-07 15:15:36 +02:00 committed by Borislav Petkov
parent 097ee5b778
commit 4b47cdbda6
4 changed files with 20 additions and 16 deletions
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2
arch/x86/include/asm/pgtable.h
View file

@ -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,

4
arch/x86/include/asm/setup.h
View file

@ -39,6 +39,8 @@ void vsmp_init(void);
static inline void vsmp_init(void) { }
#endif
struct pt_regs;
void setup_bios_corruption_check(void);
void early_platform_quirks(void);
@ -49,8 +51,8 @@ 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_setup_idt(void);
extern void __init do_early_exception(struct pt_regs *regs, int trapnr);
#ifdef CONFIG_X86_INTEL_MID
extern void x86_intel_mid_early_setup(void);

19
arch/x86/kernel/head64.c
View file

@ -38,6 +38,8 @@
#include <asm/fixmap.h>
#include <asm/realmode.h>
#include <asm/desc.h>
#include <asm/extable.h>
#include <asm/trapnr.h>
/*
* Manage page tables very early on.
@ -317,7 +319,7 @@ 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;
@ -327,7 +329,7 @@ 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;
@ -384,10 +386,10 @@ 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;
@ -397,6 +399,15 @@ 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)

11
arch/x86/kernel/head_64.S
View file

@ -341,18 +341,9 @@ 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)