[PATCH v2 4/7] ARM: mm: print out correct page table entries

Kefeng Wang
2021-06-02T06:53:52Z

Like commit 67ce16ec15ce ("arm64: mm: print out correct page table entries")
does, drop the struct mm_struct argument of show_pte(), print the tables
based on the faulting address.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
arch/arm/include/asm/bug.h | 2 +-
arch/arm/kernel/traps.c | 2 +-
arch/arm/mm/fault.c | 36 ++++++++++++++++++++----------------
3 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/arch/arm/include/asm/bug.h b/arch/arm/include/asm/bug.h
index ba8d9d7d242b..d618640e34aa 100644
--- a/arch/arm/include/asm/bug.h
+++ b/arch/arm/include/asm/bug.h
@@ -86,7 +86,7 @@ extern asmlinkage void c_backtrace(unsigned long fp, int pmode,
const char *loglvl);

struct mm_struct;
-void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr);
+void show_pte(const char *lvl, unsigned long addr);
extern void __show_regs(struct pt_regs *);
extern void __show_regs_alloc_free(struct pt_regs *regs);

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 64308e3a5d0c..98c904aeee78 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -736,7 +736,7 @@ baddataabort(int code, unsigned long instr, struct pt_regs *regs)
pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
task_pid_nr(current), current->comm, code, instr);
dump_instr(KERN_ERR, regs);
- show_pte(KERN_ERR, current->mm, addr);
+ show_pte(KERN_ERR, addr);
}
#endif

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 9a6d74f6ea1d..71a5c29488c2 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -27,15 +27,23 @@
#ifdef CONFIG_MMU

/*
- * This is useful to dump out the page tables associated with
- * 'addr' in mm 'mm'.
+ * Dump out the page tables associated with 'addr' in the currently active mm
*/
-void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
+void show_pte(const char *lvl, unsigned long addr)
{
pgd_t *pgd;
-
- if (!mm)
+ struct mm_struct *mm;
+
+ if (addr < TASK_SIZE) {
+ mm = current->active_mm;
+ if (mm == &init_mm) {
+ printk("%s[%08lx] user address but active_mm is swapper\n",
+ lvl, addr);
+ return;
+ }
+ } else {
mm = &init_mm;
+ }

printk("%spgd = %p\n", lvl, mm->pgd);
pgd = pgd_offset(mm, addr);
@@ -96,7 +104,7 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
pr_cont("\n");
}
#else /* CONFIG_MMU */
-void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
+void show_pte(const char *lvl, unsigned long addr)
{ }
#endif /* CONFIG_MMU */

@@ -104,8 +112,7 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
* Oops. The kernel tried to access some page that wasn't present.
*/
static void
-__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
- struct pt_regs *regs)
+__do_kernel_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
/*
* Are we prepared to handle this kernel fault?
@@ -122,7 +129,7 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
(addr < PAGE_SIZE) ? "NULL pointer dereference" :
"paging request", addr);

- show_pte(KERN_ALERT, mm, addr);
+ show_pte(KERN_ALERT, addr);
die("Oops", regs, fsr);
bust_spinlocks(0);
do_exit(SIGKILL);
@@ -147,7 +154,7 @@ __do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
pr_err("8<--- cut here ---\n");
pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
tsk->comm, sig, addr, fsr);
- show_pte(KERN_ERR, tsk->mm, addr);
+ show_pte(KERN_ERR, addr);
show_regs(regs);
}
#endif
@@ -166,9 +173,6 @@ __do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,

void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
- struct task_struct *tsk = current;
- struct mm_struct *mm = tsk->active_mm;
-
/*
* If we are in kernel mode at this point, we
* have no context to handle this fault with.
@@ -176,7 +180,7 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (user_mode(regs))
__do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
else
- __do_kernel_fault(mm, addr, fsr, regs);
+ __do_kernel_fault(addr, fsr, regs);
}

#ifdef CONFIG_MMU
@@ -336,7 +340,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
return 0;

no_context:
- __do_kernel_fault(mm, addr, fsr, regs);
+ __do_kernel_fault(addr, fsr, regs);
return 0;
}
#else /* CONFIG_MMU */
@@ -503,7 +507,7 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
pr_alert("8<--- cut here ---\n");
pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
inf->name, fsr, addr);
- show_pte(KERN_ALERT, current->mm, addr);
+ show_pte(KERN_ALERT, addr);

arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
fsr, 0);
--
2.26.2