[Crash-utility] [PATCH] s390x: Add page table walk information to vtop command

[Michael Holzheu]

Hello Dave,

This patch adds some output to the vtop command on s390x. Like on x86 we now
print information for the page table walk:

 * "Region-First-Table Entry" (RFTE)
 * "Region-Second-Table Entry" (RSTE)
 * "Region-Third-Table Entry" (RTTE)
 * "Segment Table Entry" (STE)
 * "Page Table Entry" (PTE)
 * "Read address of page" (PAGE)

Depending on the size of the address space the page tables can start at
different levels.

Example for three level page tables:

  crash> vtop 3ff8000c000
  VIRTUAL           PHYSICAL
  3ff8000c000       2e3832000

  PAGE DIRECTORY: 0000000000aaa000
   RTTE: 0000000000aadff8 => 00000002e3c00007
    STE: 00000002e3c00000 => 00000002e3df7000
    PTE: 00000002e3df7060 => 00000002e383203d
   PAGE: 00000002e3832000

        PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
  3d10b8e0c80      2e3832000                0        0  1 7fffc0000000000

The first entry e.g. "PTE: 00000002e3df7060" is the physical address
of the entry in the table. The second, e.g. "=> 00000002e383203d" is the
content of the entry itself (address and flags).

Reviewed-by: Heiko Carstens <heiko.carstens at de.ibm.com>
Tested-by: Mikhail Zaslonko <zaslonko at linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
---
 s390x.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/s390x.c b/s390x.c
index 96ce3dc..9246f75 100644
--- a/s390x.c
+++ b/s390x.c
@@ -613,16 +613,19 @@ static inline int s390x_pte_present(unsigned long x){
 
 /* Region or segment table traversal function */
 static ulong _kl_rsg_table_deref_s390x(ulong vaddr, ulong table,
-					 int len, int level)
+				       int len, int level, int verbose)
 {
-	ulong offset, entry;
+	const char *name_vec[] = {"STE", "RTTE", "RSTE", "RFTE"};
+	ulong offset, entry, addr;
 
 	offset = ((vaddr >> (11*level + 20)) & 0x7ffULL) * 8;
 	if (offset >= (len + 1)*4096)
 		/* Offset is over the table limit. */
 		return 0;
-	readmem(table + offset, KVADDR, &entry, sizeof(entry), "entry",
-		FAULT_ON_ERROR);
+	addr = table + offset;
+	readmem(addr, KVADDR, &entry, sizeof(entry), "entry", FAULT_ON_ERROR);
+	if (verbose)
+		fprintf(fp, "%5s: %016lx => %016lx\n", name_vec[level], addr, entry);
 	/*
 	 * Check if the segment table entry could be read and doesn't have
 	 * any of the reserved bits set.
@@ -653,13 +656,17 @@ static int swap_entry(ulong entry)
 }
 
 /* Page table traversal function */
-static ulong _kl_pg_table_deref_s390x(ulong vaddr, ulong table)
+static ulong _kl_pg_table_deref_s390x(ulong vaddr, ulong table, int verbose)
 {
-	ulong offset, entry;
+	ulong offset, entry, addr;
 
 	offset = ((vaddr >> 12) & 0xffULL) * 8;
-	readmem(table + offset, KVADDR, &entry, sizeof(entry), "entry",
-		FAULT_ON_ERROR);
+	addr = table + offset;
+	readmem(addr, KVADDR, &entry, sizeof(entry), "entry", FAULT_ON_ERROR);
+	if (verbose) {
+		fprintf(fp, "%5s: %016lx => %016lx\n", "PTE", addr, entry);
+		fprintf(fp, "%5s: %016llx\n", "PAGE", entry & ~0xfffULL);
+	}
 	/*
 	 * Return zero if the page table entry has the reserved (0x800) or
 	 * the invalid (0x400) bit set and it is not a swap entry.
@@ -676,6 +683,9 @@ int s390x_vtop(ulong table, ulong vaddr, physaddr_t *phys_addr, int verbose)
 	ulong entry, paddr;
 	int level, len;
 
+	if (verbose)
+		fprintf(fp, "PAGE DIRECTORY: %016lx\n", table);
+
 	*phys_addr = 0;
 	/*
 	 * Walk the region and segment tables.
@@ -693,7 +703,8 @@ int s390x_vtop(ulong table, ulong vaddr, physaddr_t *phys_addr, int verbose)
 		return FALSE;
 	}
 	while (level >= 0) {
-		entry = _kl_rsg_table_deref_s390x(vaddr, table, len, level);
+		entry = _kl_rsg_table_deref_s390x(vaddr, table, len, level,
+						  verbose);
 		if (!entry)
 			return FALSE;
 		table = entry & ~0xfffULL;
@@ -717,7 +728,7 @@ int s390x_vtop(ulong table, ulong vaddr, physaddr_t *phys_addr, int verbose)
 	}
 
 	/* Get the page table entry */
-	entry = _kl_pg_table_deref_s390x(vaddr, entry & ~0x7ffULL);
+	entry = _kl_pg_table_deref_s390x(vaddr, entry & ~0x7ffULL, verbose);
 	if (!entry)
 		return FALSE;
 
-- 
2.11.2

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