Re: [Xen-devel] [PATCH 03/38] arm: handy function to print a walk of a domain's p2m.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

> > > > > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > > > > index 4f624d8..fdbecbc 100644
> > > > > --- a/xen/arch/arm/p2m.c
> > > > > +++ b/xen/arch/arm/p2m.c
> > > > > @@ -5,6 +5,40 @@
> > > > >  #include <xen/domain_page.h>
> > > > >  #include <asm/flushtlb.h>
> > > > >  
> > > > > +void dump_p2m_lookup(struct domain *d, paddr_t addr)
> > > > > +{
[...]
> > > > > +}
> > > > 
> > > > Can this be unified with dump_pt_walk?
> > > 
> > > Not all that easily, mainly because dump_pt_walk walks xenheap pages
> > > (which don't need mapping) while dump_p2m_walk dumps domheap pages
> > > (which need mapping as we go). I probably could write something generic
> > > enough but I fear that it would be a mass of if's.
> > 
> > Is there any harm in mapping xenheap pages?  Since this is only invoked
> > on error paths, we don't particularly need it to be fast. 
> 
> For some reason I thought it just didn't work -- I'll give it a go
> though.

Well it works, this means that this patch and the previous patch then
collapse down into a single patch:

8<-------------------------------------------------------

>From 055fe5f4a3a77f292d5a2a6b9f56a4d14dad3519 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date: Fri, 2 Mar 2012 12:02:42 +0000
Subject: [PATCH] arm: handy function to print a walk of a page table

Include helpers for dumping hypervisor walks and guest p2m walks.

Useful for debug but not actually used in this patch.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/arch/arm/mm.c          |   49 +++++++++++++++++++++++++++++++++++++++++++-
 xen/arch/arm/p2m.c         |   15 +++++++++++++
 xen/include/asm-arm/page.h |   26 +++++++++++++++++++++++
 3 files changed, 89 insertions(+), 1 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 10ff883..715a98a 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -26,6 +26,7 @@
 #include <xen/preempt.h>
 #include <xen/errno.h>
 #include <xen/guest_access.h>
+#include <xen/domain_page.h>
 #include <asm/page.h>
 #include <asm/current.h>
 #include <public/memory.h>
@@ -42,6 +43,8 @@ static lpae_t xen_xenmap[LPAE_ENTRIES] 
__attribute__((__aligned__(4096)));
 /* Non-boot CPUs use this to find the correct pagetables. */
 uint64_t boot_httbr;
 
+static paddr_t phys_offset;
+
 /* Limits of the Xen heap */
 unsigned long xenheap_mfn_start, xenheap_mfn_end;
 unsigned long xenheap_virt_end;
@@ -53,6 +56,50 @@ unsigned long max_page;
 
 extern char __init_begin[], __init_end[];
 
+void dump_pt_walk(lpae_t *first, paddr_t addr)
+{
+    lpae_t *second = NULL, *third = NULL;
+
+    if ( first_table_offset(addr) >= LPAE_ENTRIES )
+        return;
+
+    printk("1ST[0x%llx] = 0x%"PRIpaddr"\n",
+           first_table_offset(addr),
+           first[first_table_offset(addr)].bits);
+    if ( !first[first_table_offset(addr)].walk.valid ||
+         !first[first_table_offset(addr)].walk.table )
+        goto done;
+
+    second = map_domain_page(first[first_table_offset(addr)].walk.base);
+    printk("2ND[0x%llx] = 0x%"PRIpaddr"\n",
+           second_table_offset(addr),
+           second[second_table_offset(addr)].bits);
+    if ( !second[second_table_offset(addr)].walk.valid ||
+         !second[second_table_offset(addr)].walk.table )
+        goto done;
+
+    third = map_domain_page(second[second_table_offset(addr)].walk.base);
+    printk("3RD[0x%llx] = 0x%"PRIpaddr"\n",
+           third_table_offset(addr),
+           third[third_table_offset(addr)].bits);
+
+done:
+    if (third) unmap_domain_page(third);
+    if (second) unmap_domain_page(second);
+
+}
+
+void dump_hyp_walk(uint32_t addr)
+{
+    uint64_t httbr = READ_CP64(HTTBR);
+
+    printk("Walking Hypervisor VA 0x%08"PRIx32" via HTTBR 0x%016"PRIx64"\n",
+           addr, httbr);
+
+    BUG_ON( (lpae_t *)(unsigned long)(httbr - phys_offset) != xen_pgtable );
+    dump_pt_walk(xen_pgtable, addr);
+}
+
 /* Map a 4k page in a fixmap entry */
 void set_fixmap(unsigned map, unsigned long mfn, unsigned attributes)
 {
@@ -159,7 +206,7 @@ void unmap_domain_page(const void *va)
  * Changes here may need matching changes in head.S */
 void __init setup_pagetables(unsigned long boot_phys_offset)
 {
-    paddr_t xen_paddr, phys_offset;
+    paddr_t xen_paddr;
     unsigned long dest_va;
     lpae_t pte, *p;
     int i;
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 4f624d8..ea385a6 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -5,6 +5,21 @@
 #include <xen/domain_page.h>
 #include <asm/flushtlb.h>
 
+void dump_p2m_lookup(struct domain *d, paddr_t addr)
+{
+    struct p2m_domain *p2m = &d->arch.p2m;
+    lpae_t *first;
+
+    printk("dom%d IPA 0x%"PRIpaddr"\n", d->domain_id, addr);
+
+    printk("P2M @ %p mfn:0x%lx\n",
+           p2m->first_level, page_to_mfn(p2m->first_level));
+
+    first = __map_domain_page(p2m->first_level);
+    dump_pt_walk(first, addr);
+    unmap_domain_page(first);
+}
+
 void p2m_load_VTTBR(struct domain *d)
 {
     struct p2m_domain *p2m = &d->arch.p2m;
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index b6df64e..183ba5f 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -132,10 +132,28 @@ typedef struct {
     unsigned long sbz1:5;
 } __attribute__((__packed__)) lpae_p2m_t;
 
+/*
+ * Walk is the common bits of p2m and pt entries which are needed to
+ * simply walk the table (e.g. for debug).
+ */
+typedef struct {
+    /* These are used in all kinds of entry. */
+    unsigned long valid:1;      /* Valid mapping */
+    unsigned long table:1;      /* == 1 in 4k map entries too */
+
+    unsigned long pad2:10;
+
+    /* The base address must be appropriately aligned for Block entries */
+    unsigned long base:28;      /* Base address of block or next table */
+
+    unsigned long pad1:24;
+} __attribute__((__packed__)) lpae_walk_t;
+
 typedef union {
     uint64_t bits;
     lpae_pt_t pt;
     lpae_p2m_t p2m;
+    lpae_walk_t walk;
 } lpae_t;
 
 /* Standard entry type that we'll use to build Xen's own pagetables.
@@ -252,6 +270,14 @@ static inline void flush_guest_tlb(void)
     WRITE_CP32(r0 /* dummy */, TLBIALLNSNH);
 }
 
+/* Print a walk of an arbitrary page table */
+void dump_pt_walk(lpae_t *table, paddr_t addr);
+
+/* Print a walk of the hypervisor's page tables for a virtual addr. */
+extern void dump_hyp_walk(uint32_t addr);
+/* Print a walk of the p2m for a domain for a physical address. */
+extern void dump_p2m_lookup(struct domain *d, paddr_t addr);
+
 /* Ask the MMU to translate a VA for us */
 static inline uint64_t __va_to_par(uint32_t va)
 {
-- 
1.7.9.1





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