Re: [PATCH v2] arm64/mm: Refactor {pgd, pud, pmd, pte}_ERROR()

[Gavin Shan]

Hi Anshuman,

On 9/14/20 3:31 PM, Anshuman Khandual wrote:

On 09/14/2020 05:17 AM, Gavin Shan wrote:

The function __{pgd, pud, pmd, pte}_error() are introduced so that
they can be called by {pgd, pud, pmd, pte}_ERROR(). However, some
of the functions could never be called when the corresponding page
table level isn't enabled. For example, __{pud, pmd}_error() are
unused when PUD and PMD are folded to PGD.

Right, it makes sense not to have these helpers generally available.
Given pxx_ERROR() is enabled only when required page table level is
available, with a CONFIG_PGTABLE_LEVEL check.

Yep.

This removes __{pgd, pud, pmd, pte}_error() and call pr_err() from
{pgd, pud, pmd, pte}_ERROR() directly, similar to what x86/powerpc
are doing. With this, the code looks a bit simplified either.

Do we need p4d_ERROR() here as well !

p4d_ERROR() is defined in include/asm-generic/pgtable-nop4d.h, which
is always included because we have 4 levels of page tables to the
maximum.

Signed-off-by: Gavin Shan <gs...@redhat.com>
---
v2: Fix build warning caused by wrong printk format
---
  arch/arm64/include/asm/pgtable.h | 17 ++++++++---------
  arch/arm64/kernel/traps.c        | 20 --------------------
  2 files changed, 8 insertions(+), 29 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index d5d3fbe73953..e0ab81923c30 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -35,11 +35,6 @@

extern struct page *vmemmap; -extern void __pte_error(const char *file, int line, unsigned long val);

-extern void __pmd_error(const char *file, int line, unsigned long val);
-extern void __pud_error(const char *file, int line, unsigned long val);
-extern void __pgd_error(const char *file, int line, unsigned long val);
-
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE

@@ -57,7 +52,8 @@ extern void __pgd_error(const char *file, int line, unsigned long val);

  extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
  #define ZERO_PAGE(vaddr)      phys_to_page(__pa_symbol(empty_zero_page))

-#define pte_ERROR(pte) __pte_error(__FILE__, __LINE__, pte_val(pte))

+#define pte_ERROR(e)   \
+       pr_err("%s:%d: bad pte %016llx.\n", __FILE__, __LINE__, pte_val(e))

/*

   * Macros to convert between a physical address and its placement in a
@@ -541,7 +537,8 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)

#if CONFIG_PGTABLE_LEVELS > 2 -#define pmd_ERROR(pmd) __pmd_error(__FILE__, __LINE__, pmd_val(pmd))

+#define pmd_ERROR(e)   \
+       pr_err("%s:%d: bad pmd %016llx.\n", __FILE__, __LINE__, pmd_val(e))

#define pud_none(pud) (!pud_val(pud))

  #define pud_bad(pud)          (!(pud_val(pud) & PUD_TABLE_BIT))
@@ -608,7 +605,8 @@ static inline unsigned long pud_page_vaddr(pud_t pud)

#if CONFIG_PGTABLE_LEVELS > 3 -#define pud_ERROR(pud) __pud_error(__FILE__, __LINE__, pud_val(pud))

+#define pud_ERROR(e)   \
+       pr_err("%s:%d: bad pud %016llx.\n", __FILE__, __LINE__, pud_val(e))

#define p4d_none(p4d) (!p4d_val(p4d))

  #define p4d_bad(p4d)          (!(p4d_val(p4d) & 2))
@@ -667,7 +665,8 @@ static inline unsigned long p4d_page_vaddr(p4d_t p4d)

#endif /* CONFIG_PGTABLE_LEVELS > 3 */ -#define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd))

+#define pgd_ERROR(e)   \
+       pr_err("%s:%d: bad pgd %016llx.\n", __FILE__, __LINE__, pgd_val(e))

A line break in these macros might not be required any more, as checkpatch.pl
now accepts bit longer lines.

Correct, but I guess it's nice to limit the width to 80 characters :)

#define pgd_set_fixmap(addr) ((pgd_t *)set_fixmap_offset(FIX_PGD, addr))

  #define pgd_clear_fixmap()    clear_fixmap(FIX_PGD)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 13ebd5ca2070..12fba7136dbd 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -935,26 +935,6 @@ asmlinkage void enter_from_user_mode(void)
  }
  NOKPROBE_SYMBOL(enter_from_user_mode);

-void __pte_error(const char *file, int line, unsigned long val)

-{
-       pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
-}
-
-void __pmd_error(const char *file, int line, unsigned long val)
-{
-       pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
-}
-
-void __pud_error(const char *file, int line, unsigned long val)
-{
-       pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
-}
-
-void __pgd_error(const char *file, int line, unsigned long val)
-{
-       pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
-}

While moving %016lx now becomes %016llx. I guess this should be okay.
Looks much cleaner to have removed these helpers from trap.c

Yep.

-
  /* GENERIC_BUG traps */

int is_valid_bugaddr(unsigned long addr)

Thanks,
Gavin