diff mbox series

[2/6] xen/memory: Remove tail padding from TRC_MEM_* records

Message ID 20210917084559.22673-3-andrew.cooper3@citrix.com (mailing list archive)
State Superseded
Headers show
Series xen/trace: Fix leakage of uninitialised stack into the tracebuffer | expand

Commit Message

Andrew Cooper Sept. 17, 2021, 8:45 a.m. UTC 
Four TRC_MEM_* records supply custom structures with tail padding, leaking
stack rubble into the trace buffer.  Three of the records were fine in 32-bit
builds of Xen, due to the relaxed alignment of 64-bit integers, but
POD_SUPERPAGE_SPLITER was broken right from the outset.

We could pack the datastructures to remove the padding, but xentrace_format
has no way of rendering the upper half of a 16-bit field.  Instead, expand all
16-bit fields to 32-bit.

For POD_SUPERPAGE_SPLINTER, introduce an order field as it is relevant
information, and to matche DECREASE_RESERVATION, and so it doesn't require a
__packed attribute to drop tail padding.

Update xenalyze's structures to match, and introduce xentrace_format rendering
which was absent previously.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Ian Jackson <iwj@xenproject.org>
CC: Jan Beulich <JBeulich@suse.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Wei Liu <wl@xen.org>
CC: Julien Grall <julien@xen.org>
CC: Dario Faggioli <dfaggioli@suse.com>

The xentrace_format script isn't remotely Py3 compatible, and was another
script missed by our previous efforts.
---
 tools/xentrace/formats    |  4 ++++
 tools/xentrace/xenalyze.c | 12 ++++++------
 xen/arch/x86/mm/p2m-pod.c | 17 +++++++++--------
 xen/common/memory.c       |  4 ++--
 4 files changed, 21 insertions(+), 16 deletions(-)

Comments

Jan Beulich Sept. 17, 2021, 1:04 p.m. UTC | #1 
On 17.09.2021 10:45, Andrew Cooper wrote:
> Four TRC_MEM_* records supply custom structures with tail padding, leaking
> stack rubble into the trace buffer.  Three of the records were fine in 32-bit
> builds of Xen, due to the relaxed alignment of 64-bit integers, but
> POD_SUPERPAGE_SPLITER was broken right from the outset.
> 
> We could pack the datastructures to remove the padding, but xentrace_format
> has no way of rendering the upper half of a 16-bit field.  Instead, expand all
> 16-bit fields to 32-bit.
> 
> For POD_SUPERPAGE_SPLINTER, introduce an order field as it is relevant
> information, and to matche DECREASE_RESERVATION, and so it doesn't require a
> __packed attribute to drop tail padding.
> 
> Update xenalyze's structures to match, and introduce xentrace_format rendering
> which was absent previously.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Hypervisor part
Reviewed-by: Jan Beulich <jbeulich@suse.com>

Jan
diff mbox series

Patch

diff --git a/tools/xentrace/formats b/tools/xentrace/formats
index deac4d8598b0..0fcc327a4078 100644
--- a/tools/xentrace/formats
+++ b/tools/xentrace/formats
@@ -136,6 +136,10 @@ 
 0x0010f001  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  page_grant_map      [ domid = %(1)d ]
 0x0010f002  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  page_grant_unmap    [ domid = %(1)d ]
 0x0010f003  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  page_grant_transfer [ domid = %(1)d ]
+0x0010f005  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  decrease_reservation   [ d%(3)d gfn 0x%(2)08x%(1)08x, order %(4)u ]
+0x0010f010  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  pod_populate           [ d%(5)d gfn 0x%(2)08x%(1)08x => mfn 0x%(4)08x%(3)08x, order %(6)u ]
+0x0010f011  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  pod_zero_reclaim       [ d%(5)d gfn 0x%(2)08x%(1)08x => mfn 0x%(4)08x%(3)08x, order %(6)u ]
+0x0010f012  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  pod_superpage_splinter [ d%(3)d gfn 0x%(2)08x%(1)08x, order %(4)u ]
 
 0x00201001  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  hypercall  [ eip = 0x%(1)08x, eax = 0x%(2)08x ]
 0x00201101  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  hypercall  [ rip = 0x%(2)08x%(1)08x, eax = 0x%(3)08x ]
diff --git a/tools/xentrace/xenalyze.c b/tools/xentrace/xenalyze.c
index 5de167031e01..12dcca964645 100644
--- a/tools/xentrace/xenalyze.c
+++ b/tools/xentrace/xenalyze.c
@@ -8121,7 +8121,7 @@  void mem_pod_zero_reclaim_process(struct pcpu_info *p)
 
     struct {
         uint64_t gfn, mfn;
-        int d:16,order:16;
+        uint32_t d, order;
     } *r = (typeof(r))ri->d;
 
     if ( v && v->hvm.vmexit_valid )
@@ -8171,7 +8171,7 @@  void mem_pod_populate_process(struct pcpu_info *p)
 
     struct {
         uint64_t gfn, mfn;
-        int d:16,order:16;
+        uint32_t d, order;
     } *r = (typeof(r))ri->d;
 
     if ( opt.dump_all )
@@ -8204,14 +8204,14 @@  void mem_pod_superpage_splinter_process(struct pcpu_info *p)
 
     struct {
         uint64_t gfn;
-        int d:16;
+        uint32_t d, order;
     } *r = (typeof(r))ri->d;
 
     if ( opt.dump_all )
     {
-        printf(" %s pod_spage_splinter d%d g %llx\n",
+        printf(" %s pod_spage_splinter d%d o%d g %"PRIx64"\n",
                ri->dump_header,
-               r->d, (unsigned long long)r->gfn);
+               r->d, r->order, r->gfn);
     }
 }
 
@@ -8255,7 +8255,7 @@  void mem_decrease_reservation_process(struct pcpu_info *p)
 
     struct {
         uint64_t gfn;
-        int d:16,order:16;
+        uint32_t d, order;
     } *r = (typeof(r))ri->d;
 
     if ( opt.dump_all )
diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index 8abc57265c10..90f02ae765f6 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -819,8 +819,8 @@  p2m_pod_zero_check_superpage(struct p2m_domain *p2m, gfn_t gfn)
     if ( tb_init_done )
     {
         struct {
-            u64 gfn, mfn;
-            int d:16,order:16;
+            uint64_t gfn, mfn;
+            uint32_t d, order;
         } t;
 
         t.gfn = gfn_x(gfn);
@@ -987,8 +987,8 @@  p2m_pod_zero_check(struct p2m_domain *p2m, const gfn_t *gfns, unsigned int count
             if ( tb_init_done )
             {
                 struct {
-                    u64 gfn, mfn;
-                    int d:16,order:16;
+                    uint64_t gfn, mfn;
+                    uint32_t d, order;
                 } t;
 
                 t.gfn = gfn_x(gfns[i]);
@@ -1217,8 +1217,8 @@  p2m_pod_demand_populate(struct p2m_domain *p2m, gfn_t gfn,
     if ( tb_init_done )
     {
         struct {
-            u64 gfn, mfn;
-            int d:16,order:16;
+            uint64_t gfn, mfn;
+            uint32_t d, order;
         } t;
 
         t.gfn = gfn_x(gfn);
@@ -1260,12 +1260,13 @@  p2m_pod_demand_populate(struct p2m_domain *p2m, gfn_t gfn,
     if ( tb_init_done )
     {
         struct {
-            u64 gfn;
-            int d:16;
+            uint64_t gfn;
+            uint32_t d, order;
         } t;
 
         t.gfn = gfn_x(gfn);
         t.d = d->domain_id;
+        t.order = order;
 
         __trace_var(TRC_MEM_POD_SUPERPAGE_SPLINTER, 0, sizeof(t), &t);
     }
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 63642278fda9..8fd88ccb70bf 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -450,8 +450,8 @@  static void decrease_reservation(struct memop_args *a)
         if ( tb_init_done )
         {
             struct {
-                u64 gfn;
-                int d:16,order:16;
+                uint64_t gfn;
+                uint32_t d, order;
             } t;
 
             t.gfn = gmfn;