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 fffb8bf772
VIRTUAL           PHYSICAL
fffb8bf772        40000001231bf772

SEGMENT: xuvrange
PAGE DIRECTORY: 9000000096d10000
  PGD: 9000000096d10078 => 900000009665c000
  PMD: 000000009665ffe8 => 9000000098894000
  PTE: 0000000098897178 => 40000001231bc39f
 PAGE: 40000001231bc000

      PTE             PHYSICAL      FLAGS
40000001231bc39f  40000001231bc000  
(VALID|DIRTY|PLV|PRESENT|WRITE|PROTNONE|NO_EXEC)

      VMA              START             END        FLAGS FILE
90000000a4927660       fffb89c000       fffb8c0000 100173

Co-developed-by: Youling Tang <[email protected]>
Signed-off-by: Youling Tang <[email protected]>
Signed-off-by: Ming Wang <[email protected]>
---
 loongarch64.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/loongarch64.c b/loongarch64.c
index 4e63e40..15d1474 100644
--- a/loongarch64.c
+++ b/loongarch64.c
@@ -46,6 +46,8 @@ static int loongarch64_uvtop(struct task_context *tc, ulong 
vaddr,
                        physaddr_t *paddr, int verbose);
 static int loongarch64_kvtop(struct task_context *tc, ulong kvaddr,
                        physaddr_t *paddr, int verbose);
+static int loongarch64_translate_pte(ulong pte, void *physaddr,
+                       ulonglong pte64);
 
 /*
  * 3 Levels paging       PAGE_SIZE=16KB
@@ -80,6 +82,110 @@ typedef struct { ulong pte; } pte_t;
 
 static struct machine_specific loongarch64_machine_specific = { 0 };
 
+/*
+ * Check and print the flags on the page
+ */
+static void
+check_page_flags(ulong pte)
+{
+#define CHECK_PAGE_FLAG(flag)                          \
+       if ((_PAGE_##flag) && (pte & _PAGE_##flag))     \
+               fprintf(fp, "%s" #flag, others++ ? "|" : "")
+
+       int others = 0;
+       fprintf(fp, "(");
+
+       if (pte) {
+               CHECK_PAGE_FLAG(VALID);
+               CHECK_PAGE_FLAG(DIRTY);
+               CHECK_PAGE_FLAG(PLV);
+
+               /* Determine whether it is a huge page format */
+               if (pte & _PAGE_HGLOBAL) {
+                       CHECK_PAGE_FLAG(HUGE);
+                       CHECK_PAGE_FLAG(HGLOBAL);
+               } else {
+                       CHECK_PAGE_FLAG(GLOBAL);
+               }
+
+               CHECK_PAGE_FLAG(PRESENT);
+               CHECK_PAGE_FLAG(WRITE);
+               CHECK_PAGE_FLAG(PROTNONE);
+               CHECK_PAGE_FLAG(SPECIAL);
+               CHECK_PAGE_FLAG(NO_READ);
+               CHECK_PAGE_FLAG(NO_EXEC);
+               CHECK_PAGE_FLAG(RPLV);
+       } else {
+               fprintf(fp, "no mapping");
+       }
+
+       fprintf(fp, ")\n");
+}
+
+/*
+ * Translate a PTE, returning TRUE if the page is present.
+ * If a physaddr pointer is passed in, don't print anything.
+ */
+static int
+loongarch64_translate_pte(ulong pte, void *physaddr, ulonglong unused)
+{
+       char ptebuf[BUFSIZE];
+       char physbuf[BUFSIZE];
+       char buf1[BUFSIZE];
+       char buf2[BUFSIZE];
+       char buf3[BUFSIZE];
+       char *arglist[MAXARGS];
+       int page_present;
+       int c, len1, len2, len3;
+       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(buf1, len1, CENTER | LJUST, "PTE"));
+
+       if (!page_present) {
+               swap_location(pte, buf1);
+               if ((c = parse_line(buf1, arglist)) != 3)
+                       error(FATAL, "cannot determine swap location\n");
+
+               len2 = MAX(strlen(arglist[0]), strlen("SWAP"));
+               len3 = MAX(strlen(arglist[2]), strlen("OFFSET"));
+
+               fprintf(fp, "%s  %s\n",
+                       mkstring(buf2, len2, CENTER|LJUST, "SWAP"),
+                       mkstring(buf3, len3, CENTER|LJUST, "OFFSET"));
+
+               strcpy(buf2, arglist[0]);
+               strcpy(buf3, arglist[2]);
+               fprintf(fp, "%s  %s  %s\n",
+                       mkstring(ptebuf, len1, CENTER|RJUST, NULL),
+                       mkstring(buf2, len2, CENTER|RJUST, NULL),
+                       mkstring(buf3, len3, CENTER|RJUST, NULL));
+               return page_present;
+       }
+
+       sprintf(physbuf, "%lx", paddr);
+       len2 = MAX(strlen(physbuf), strlen("PHYSICAL"));
+       fprintf(fp, "%s  ", mkstring(buf1, len2, CENTER | LJUST, "PHYSICAL"));
+
+       fprintf(fp, "FLAGS\n");
+       fprintf(fp, "%s  %s  ",
+               mkstring(ptebuf, len1, CENTER | RJUST, NULL),
+               mkstring(physbuf, len2, CENTER | RJUST, NULL));
+
+       check_page_flags(pte);
+
+       return page_present;
+}
+
 /*
  * Identify and print the segment name to which the virtual address belongs
  */
@@ -147,6 +253,21 @@ loongarch64_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");
+                       loongarch64_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));
+               loongarch64_translate_pte(pte_val, 0, 0);
+       }
+
        return TRUE;
 no_page:
        fprintf(fp, "invalid\n");
@@ -347,6 +468,7 @@ loongarch64_init(int when)
                machdep->processor_speed = loongarch64_processor_speed;
                machdep->get_stackbase = generic_get_stackbase;
                machdep->get_stacktop = generic_get_stacktop;
+               machdep->translate_pte = loongarch64_translate_pte;
                machdep->memory_size = generic_memory_size;
                machdep->is_task_addr = loongarch64_is_task_addr;
                machdep->get_smp_cpus = loongarch64_get_smp_cpus;
-- 
2.39.2
--
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