The pte command converts the pte table entry into a physical address and
displays the page flags. Also fixed the pte part in the vtop command.

E.g. With this patch:
crash> vtop ffffffffc0004000
VIRTUAL           PHYSICAL
ffffffffc0004000  2504ac000

SEGMENT: sseg
PAGE DIRECTORY: ffffffff81330000
  PGD: ffffffff81333ff8 => 9800000255828000
  PMD: 000000025582bf00 => 98000002504bc000
  PTE: 00000002504bc008 => 0000001282563e0f
 PAGE: 00000002504ac000

   PTE      PHYSICAL   FLAGS
1282563e0f  2504ac000  (PRESENT|WRITE|ACCESSED|MODIFIED|GLOBAL|VALID|DIRTY)

      PAGE       PHYSICAL      MAPPING       INDEX CNT FLAGS
9800000257f04ac0 2504ac000                0        0  1 2501fff000000
crash> pte 1282563e0f
   PTE      PHYSICAL   FLAGS
1282563e0f  2504ac000  (PRESENT|WRITE|ACCESSED|MODIFIED|GLOBAL|VALID|DIRTY)

Signed-off-by: Huacai Chen <chenhua...@loongson.cn>
Signed-off-by: Youling Tang <tangyoul...@loongson.cn>
---
v1 -> v2:
 - No change.

 mips64.c | 118 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)

diff --git a/mips64.c b/mips64.c
index 89de5c3..e4cdaf5 100644
--- a/mips64.c
+++ b/mips64.c
@@ -23,6 +23,9 @@ static int mips64_uvtop(struct task_context *tc, ulong vaddr,
                        physaddr_t *paddr, int verbose);
 static int mips64_kvtop(struct task_context *tc, ulong kvaddr,
                        physaddr_t *paddr, int verbose);
+static void mips64_init_page_flags(void);
+static int mips64_translate_pte(ulong pte, void *physaddr,
+                       ulonglong pte64);
 
 /*
  * 3 Levels paging       PAGE_SIZE=16KB
@@ -75,6 +78,104 @@ static struct machine_specific mips64_machine_specific = { 
0 };
 static struct mips64_register *panic_task_regs;
 
 /*
+ * 31                15 14    12 11 10  9  8  7  6  5  4  3  2  1  0
+ * +-------------------+--------+--+--+--+--+--+--+--+--+--+--+--+--+
+ * |       VPN         |    C   | D| V| G|RI|XI|SP|PN| H| M| A| W| P|
+ * +-------------------+--------+--+--+--+--+--+--+--+--+--+--+--+--+
+ */
+static void
+mips64_init_page_flags(void)
+{
+       ulong shift = 0;
+
+       _PAGE_PRESENT = 1UL << shift++;
+       _PAGE_WRITE = 1UL << shift++;
+       _PAGE_ACCESSED = 1UL << shift++;
+       _PAGE_MODIFIED = 1UL << shift++;
+       _PAGE_HUGE = 1UL << shift++;
+       _PAGE_PROTNONE = 1UL << shift++;
+
+       if (THIS_KERNEL_VERSION >= LINUX(4,5,0))
+               _PAGE_SPECIAL = 1UL << shift++;
+
+       _PAGE_NO_EXEC = 1UL << shift++;
+       _PAGE_NO_READ = _PAGE_READ = 1UL << shift++;
+       _PAGE_GLOBAL = 1UL << shift++;
+       _PAGE_VALID = 1UL << shift++;
+       _PAGE_DIRTY = 1UL << shift++;
+
+       _PFN_SHIFT =  PAGESHIFT() - 12 + shift + 3;
+}
+
+/*
+ * Translate a PTE, returning TRUE if the page is present.
+ * If a physaddr pointer is passed in, don't print anything.
+ */
+static int
+mips64_translate_pte(ulong pte, void *physaddr, ulonglong pte64)
+{
+       char ptebuf[BUFSIZE];
+       char physbuf[BUFSIZE];
+       char buf[BUFSIZE];
+       int page_present;
+       int len1, len2, others;
+       ulong paddr;
+
+       paddr = PTOB(pte >> _PFN_SHIFT);
+       page_present = !!(pte & _PAGE_PRESENT);
+
+       if (physaddr) {
+               *(ulong *)physaddr = paddr;
+               return page_present;
+       }
+
+       sprintf(ptebuf, "%lx", pte);
+       len1 = MAX(strlen(ptebuf), strlen("PTE"));
+       fprintf(fp, "%s  ", mkstring(buf, len1, CENTER | LJUST, "PTE"));
+
+       if (!page_present)
+               return page_present;
+
+       sprintf(physbuf, "%lx", paddr);
+       len2 = MAX(strlen(physbuf), strlen("PHYSICAL"));
+       fprintf(fp, "%s  ", mkstring(buf, len2, CENTER | LJUST, "PHYSICAL"));
+
+       fprintf(fp, "FLAGS\n");
+       fprintf(fp, "%s  %s  ",
+               mkstring(ptebuf, len1, CENTER | RJUST, NULL),
+               mkstring(physbuf, len2, CENTER | RJUST, NULL));
+
+       fprintf(fp, "(");
+       others = 0;
+
+#define CHECK_PAGE_FLAG(flag)                          \
+       if ((_PAGE_##flag) && (pte & _PAGE_##flag))     \
+               fprintf(fp, "%s" #flag, others++ ? "|" : "")
+
+       if (pte) {
+               CHECK_PAGE_FLAG(PRESENT);
+               CHECK_PAGE_FLAG(WRITE);
+               CHECK_PAGE_FLAG(ACCESSED);
+               CHECK_PAGE_FLAG(MODIFIED);
+               CHECK_PAGE_FLAG(HUGE);
+               CHECK_PAGE_FLAG(PROTNONE);
+               CHECK_PAGE_FLAG(SPECIAL);
+               CHECK_PAGE_FLAG(NO_EXEC);
+               CHECK_PAGE_FLAG(NO_READ);
+               CHECK_PAGE_FLAG(READ);
+               CHECK_PAGE_FLAG(GLOBAL);
+               CHECK_PAGE_FLAG(VALID);
+               CHECK_PAGE_FLAG(DIRTY);
+       } else {
+               fprintf(fp, "no mapping");
+       }
+
+       fprintf(fp, ")\n");
+
+       return page_present;
+}
+
+/*
  * Virtual to physical memory translation. This function will be called
  * by both mips64_kvtop and mips64_uvtop.
  */
@@ -140,6 +241,21 @@ mips64_pgd_vtop(ulong *pgd, ulong vaddr, physaddr_t 
*paddr, int verbose)
        if (!pte_val)
                goto no_page;
 
+       if (!(pte_val & _PAGE_PRESENT)) {
+               if (verbose) {
+                       fprintf(fp, "\n");
+                       mips64_translate_pte((ulong)pte_val, 0, pte_val);
+               }
+               return FALSE;
+       }
+
+       *paddr = PTOB(pte_val >> _PFN_SHIFT) + PAGEOFFSET(vaddr);
+
+       if (verbose) {
+               fprintf(fp, " PAGE: %016lx\n\n", PAGEBASE(*paddr));
+               mips64_translate_pte(pte_val, 0, 0);
+       }
+
        return TRUE;
 no_page:
        fprintf(fp, "invalid\n");
@@ -320,6 +436,7 @@ mips64_init(int when)
                machdep->processor_speed = mips64_processor_speed;
                machdep->get_stackbase = generic_get_stackbase;
                machdep->get_stacktop = generic_get_stacktop;
+               machdep->translate_pte = mips64_translate_pte;
                machdep->memory_size = generic_memory_size;
                machdep->is_task_addr = mips64_is_task_addr;
                machdep->get_smp_cpus = mips64_get_smp_cpus;
@@ -328,6 +445,7 @@ mips64_init(int when)
                break;
 
        case POST_GDB:
+               mips64_init_page_flags();
                machdep->section_size_bits = _SECTION_SIZE_BITS;
                machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
                break;
-- 
2.1.0

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