[Xen-devel] [PATCH 1/2] trace: improve usefulness of hypercall trace record

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

Trace hypercalls using a more useful trace record format.

The EIP field is removed (it was always somewhere in the hypercall
page) and include selected hypercall arguments (the number of calls in
a multicall, and the number of PTE updates in an mmu_update).

To allow tracing tools to distinguish between the two formats, the new
format uses a new event ID (TRC_PV_HYPERCALL_V2).

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 xen/arch/x86/trace.c       |   33 +++++++++++++--------------------
 xen/common/trace.c         |   23 +++++++++++++++++++++++
 xen/include/public/trace.h |    1 +
 xen/include/xen/trace.h    |    2 ++
 4 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/xen/arch/x86/trace.c b/xen/arch/x86/trace.c
index 404f293..2b59017 100644
--- a/xen/arch/x86/trace.c
+++ b/xen/arch/x86/trace.c
@@ -14,35 +14,28 @@
 void trace_hypercall(void)
 {
     struct cpu_user_regs *regs = guest_cpu_user_regs();
+    unsigned long args[5];
 
 #ifdef __x86_64__
     if ( is_pv_32on64_vcpu(current) )
     {
-        struct {
-            u32 eip,eax;
-        } __attribute__((packed)) d;
-            
-        d.eip = regs->eip;
-        d.eax = regs->eax;
-
-        __trace_var(TRC_PV_HYPERCALL, 1, sizeof(d), &d);
+        args[0] = regs->ebx;
+        args[1] = regs->ecx;
+        args[2] = regs->edx;
+        args[3] = regs->esi;
+        args[4] = regs->edi;
     }
     else
 #endif
     {
-        struct {
-            unsigned long eip;
-            u32 eax;
-        } __attribute__((packed)) d;
-        u32 event;
-
-        event = TRC_PV_HYPERCALL;
-        event |= TRC_64_FLAG;
-        d.eip = regs->eip;
-        d.eax = regs->eax;
-
-        __trace_var(event, 1/*tsc*/, sizeof(d), &d);
+        args[0] = regs->rdi;
+        args[1] = regs->rsi;
+        args[2] = regs->rdx;
+        args[3] = regs->r10;
+        args[4] = regs->r11;
     }
+
+    __trace_hypercall(regs->eax, args);
 }
 
 void __trace_pv_trap(int trapnr, unsigned long eip,
diff --git a/xen/common/trace.c b/xen/common/trace.c
index cacaeb2..47c9a6a 100644
--- a/xen/common/trace.c
+++ b/xen/common/trace.c
@@ -816,6 +816,29 @@ unlock:
         tasklet_schedule(&trace_notify_dom0_tasklet);
 }
 
+void __trace_hypercall(unsigned long op, const unsigned long *args)
+{
+    struct {
+        uint32_t op;
+        uint32_t args[5];
+    } __attribute__((packed)) d;
+    uint32_t *a = d.args;
+
+    d.op = op;
+
+    switch (op) {
+    case __HYPERVISOR_multicall:
+        *a++ = args[1]; /* count */
+        break;
+    case __HYPERVISOR_mmu_update:
+        *a++ = args[1]; /* count */
+        break;
+    }
+
+    __trace_var(TRC_PV_HYPERCALL_V2, 1,
+                sizeof(uint32_t) * (1 + (a - d.args)), &d);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/public/trace.h b/xen/include/public/trace.h
index 0dfabe9..38a3f83 100644
--- a/xen/include/public/trace.h
+++ b/xen/include/public/trace.h
@@ -106,6 +106,7 @@
 #define TRC_PV_GDT_LDT_MAPPING_FAULT (TRC_PV + 10)
 #define TRC_PV_PTWR_EMULATION        (TRC_PV + 11)
 #define TRC_PV_PTWR_EMULATION_PAE    (TRC_PV + 12)
+#define TRC_PV_HYPERCALL_V2          (TRC_PV + 14)
   /* Indicates that addresses in trace record are 64 bits */
 #define TRC_64_FLAG               (0x100) 
 
diff --git a/xen/include/xen/trace.h b/xen/include/xen/trace.h
index b32f6c5..f601aeb 100644
--- a/xen/include/xen/trace.h
+++ b/xen/include/xen/trace.h
@@ -44,6 +44,8 @@ static inline void trace_var(u32 event, int cycles, int extra,
         __trace_var(event, cycles, extra, extra_data);
 }
 
+void __trace_hypercall(unsigned long call, const unsigned long *args);
+
 /* Convenience macros for calling the trace function. */
 #define TRACE_0D(_e)                            \
     do {                                        \
-- 
1.7.2.5


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