linux/arch/loongarch/mm/hugetlbpage.c
Tianyang Zhang ee084fa961 LoongArch: Fix panic caused by NULL-PMD in huge_pte_offset()
ERROR INFO:

CPU 25 Unable to handle kernel paging request at virtual address 0x0
         ...
 Call Trace:
 [<900000000023c30c>] huge_pte_offset+0x3c/0x58
 [<900000000057fd4c>] hugetlb_follow_page_mask+0x74/0x438
 [<900000000051fee8>] __get_user_pages+0xe0/0x4c8
 [<9000000000522414>] faultin_page_range+0x84/0x380
 [<9000000000564e8c>] madvise_vma_behavior+0x534/0xa48
 [<900000000056689c>] do_madvise+0x1bc/0x3e8
 [<9000000000566df4>] sys_madvise+0x24/0x38
 [<90000000015b9e88>] do_syscall+0x78/0x98
 [<9000000000221f18>] handle_syscall+0xb8/0x158

In some cases, pmd may be NULL and rely on NULL as the return value for
processing, so it is necessary to determine this situation here.

Cc: stable@vger.kernel.org
Fixes: bd51834d1c ("LoongArch: Return NULL from huge_pte_offset() for invalid PMD")
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2025-05-30 21:45:57 +08:00

66 lines
1.4 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
*/
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/err.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pte_t *pte = NULL;
pgd = pgd_offset(mm, addr);
p4d = p4d_alloc(mm, pgd, addr);
pud = pud_alloc(mm, p4d, addr);
if (pud)
pte = (pte_t *)pmd_alloc(mm, pud, addr);
return pte;
}
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr,
unsigned long sz)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd = NULL;
pgd = pgd_offset(mm, addr);
if (pgd_present(pgdp_get(pgd))) {
p4d = p4d_offset(pgd, addr);
if (p4d_present(p4dp_get(p4d))) {
pud = pud_offset(p4d, addr);
if (pud_present(pudp_get(pud)))
pmd = pmd_offset(pud, addr);
}
}
return (!pmd || pmd_none(pmdp_get(pmd))) ? NULL : (pte_t *) pmd;
}
uint64_t pmd_to_entrylo(unsigned long pmd_val)
{
uint64_t val;
/* PMD as PTE. Must be huge page */
if (!pmd_leaf(__pmd(pmd_val)))
panic("%s", __func__);
val = pmd_val ^ _PAGE_HUGE;
val |= ((val & _PAGE_HGLOBAL) >>
(_PAGE_HGLOBAL_SHIFT - _PAGE_GLOBAL_SHIFT));
return val;
}