Add support to xenctx for printing stack traces on x86_32 and x86_64.

To support this add xc_translate_foreign_address to libxc. This function
walks page tables and translates virtual addresses using a given domain
and vcpu page table.

Signed-off-by: Ian Campbell <Ian.Campbell@XenSource.com>

1 files changed, 192 insertions, 0 deletions

diff --git a/tools/libxc/xc_pagetab.c b/tools/libxc/xc_pagetab.c
new file mode 100644
index 0000000000..b63ea89ade
--- /dev/null
+++ b/tools/libxc/xc_pagetab.c
@@ -0,0 +1,192 @@
+/******************************************************************************
+ * xc_pagetab.c
+ *
+ * Function to translate virtual to physical addresses.
+ */
+#include "xc_private.h"
+
+#if defined(__i386__)
+
+#define L1_PAGETABLE_SHIFT_PAE	12
+#define L2_PAGETABLE_SHIFT_PAE	21
+#define L3_PAGETABLE_SHIFT_PAE	30
+
+#define L1_PAGETABLE_SHIFT		12
+#define L2_PAGETABLE_SHIFT		22
+
+#define L0_PAGETABLE_MASK_PAE	0x0000000ffffff000ULL
+#define L1_PAGETABLE_MASK_PAE	0x1ffULL
+#define L2_PAGETABLE_MASK_PAE	0x1ffULL
+#define L3_PAGETABLE_MASK_PAE	0x3ULL
+
+#define L0_PAGETABLE_MASK		0xfffff000ULL
+#define L1_PAGETABLE_MASK		0x3ffULL
+#define L2_PAGETABLE_MASK		0x3ffULL
+
+#elif defined(__x86_64__)
+
+#define L1_PAGETABLE_SHIFT_PAE	12
+#define L2_PAGETABLE_SHIFT_PAE	21
+#define L3_PAGETABLE_SHIFT_PAE	30
+#define L4_PAGETABLE_SHIFT_PAE	39
+
+#define L1_PAGETABLE_SHIFT		L1_PAGETABLE_SHIFT_PAE
+#define L2_PAGETABLE_SHIFT		L2_PAGETABLE_SHIFT_PAE
+
+#define L0_PAGETABLE_MASK_PAE	0x000000fffffff000ULL
+#define L1_PAGETABLE_MASK_PAE	0x1ffULL
+#define L2_PAGETABLE_MASK_PAE	0x1ffULL
+#define L3_PAGETABLE_MASK_PAE	0x1ffULL
+#define L4_PAGETABLE_MASK_PAE	0x1ffULL
+
+#define L0_PAGETABLE_MASK		L0_PAGETABLE_MASK_PAE
+#define L1_PAGETABLE_MASK		L1_PAGETABLE_MASK_PAE
+#define L2_PAGETABLE_MASK		L2_PAGETABLE_MASK_PAE
+
+#endif
+
+unsigned long xc_translate_foreign_address(int xc_handle, uint32_t dom,
+                                           int vcpu, unsigned long long virt )
+{
+    vcpu_guest_context_t ctx;
+    unsigned long long cr3;
+    void *pd, *pt, *pdppage = NULL, *pdp, *pml = NULL;
+    unsigned long long pde, pte, pdpe, pmle;
+    unsigned long mfn = 0;
+#if defined (__i386__)
+    static int pt_levels = 0;
+
+    if (pt_levels == 0) {
+        xen_capabilities_info_t xen_caps = "";
+
+        if (xc_version(xc_handle, XENVER_capabilities, &xen_caps) != 0)
+            goto out;
+        if (strstr(xen_caps, "xen-3.0-x86_64"))
+            pt_levels = 4;
+        else if (strstr(xen_caps, "xen-3.0-x86_32p"))
+            pt_levels = 3;
+        else if (strstr(xen_caps, "xen-3.0-x86_32"))
+            pt_levels = 2;
+        else
+            goto out;
+    }
+#elif defined (__x86_64__)
+#define pt_levels 4
+#endif
+
+    if (xc_domain_get_vcpu_context(xc_handle, dom, vcpu, &ctx) != 0) {
+        fprintf(stderr, "failed to retreive vcpu context\n");
+        goto out;
+    }
+    cr3 = ctx.ctrlreg[3];
+
+    /* Page Map Level 4 */
+
+#if defined(__i386__)
+    pmle = cr3;
+#elif defined(__x86_64__)
+    pml = xc_map_foreign_range(xc_handle, dom, PAGE_SIZE, PROT_READ, cr3 >> PAGE_SHIFT);
+    if (pml == NULL) {
+        fprintf(stderr, "failed to map PML4\n");
+        goto out;
+    }
+    pmle = *(unsigned long long *)(pml + 8 * ((virt >> L4_PAGETABLE_SHIFT_PAE) & L4_PAGETABLE_MASK_PAE));
+    if((pmle & 1) == 0) {
+        fprintf(stderr, "page entry not present in PML4\n");
+        goto out_unmap_pml;
+    }
+#endif
+
+    /* Page Directory Pointer Table */
+
+    if (pt_levels >= 3) {
+        pdppage = xc_map_foreign_range(xc_handle, dom, PAGE_SIZE, PROT_READ, pmle >> PAGE_SHIFT);
+        if (pdppage == NULL) {
+            fprintf(stderr, "failed to map PDP\n");
+            goto out_unmap_pml;
+        }
+        if (pt_levels >= 4)
+            pdp = pdppage;
+        else
+            /* PDP is only 32 bit aligned with 3 level pts */
+            pdp = pdppage + (pmle & ~(XC_PAGE_MASK | 0x1f));
+
+        pdpe = *(unsigned long long *)(pdp + 8 * ((virt >> L3_PAGETABLE_SHIFT_PAE) & L3_PAGETABLE_MASK_PAE));
+
+        if((pdpe & 1) == 0) {
+            fprintf(stderr, "page entry not present in PDP\n");
+            goto out_unmap_pdp;
+        }
+    } else {
+        pdpe = pmle;
+    }
+
+    /* Page Directory */
+
+    pd = xc_map_foreign_range(xc_handle, dom, PAGE_SIZE, PROT_READ, pdpe >> PAGE_SHIFT);
+    if (pd == NULL) {
+        fprintf(stderr, "failed to map PD\n");
+        goto out_unmap_pdp;
+    }
+
+    if (pt_levels >= 3)
+        pde = *(unsigned long long *)(pd + 8 * ((virt >> L2_PAGETABLE_SHIFT_PAE) & L2_PAGETABLE_MASK_PAE));
+    else
+        pde = *(unsigned long long *)(pd + 4 * ((virt >> L2_PAGETABLE_SHIFT) & L2_PAGETABLE_MASK));
+
+    if ((pde & 1) == 0) {
+        fprintf(stderr, "page entry not present in PD\n");
+        goto out_unmap_pd;
+    }
+
+    /* Page Table */
+
+    if (pde & 0x00000008) { /* 4M page (or 2M in PAE mode) */
+        fprintf(stderr, "Cannot currently cope with 2/4M pages\n");
+        exit(-1);
+    } else { /* 4k page */
+        pt = xc_map_foreign_range(xc_handle, dom, PAGE_SIZE, PROT_READ,
+                                  pde >> PAGE_SHIFT);
+
+        if (pt == NULL) {
+            fprintf(stderr, "failed to map PT\n");
+            goto out_unmap_pd;
+        }
+
+        if (pt_levels >= 3)
+            pte = *(unsigned long long *)(pt + 8 * ((virt >> L1_PAGETABLE_SHIFT_PAE) & L1_PAGETABLE_MASK_PAE));
+        else
+            pte = *(unsigned long long *)(pt + 4 * ((virt >> L1_PAGETABLE_SHIFT) & L1_PAGETABLE_MASK));
+
+        if ((pte & 0x00000001) == 0) {
+            fprintf(stderr, "page entry not present in PT\n");
+            goto out_unmap_pt;
+        }
+
+        if (pt_levels >= 3)
+            mfn = (pte & L0_PAGETABLE_MASK_PAE) >> PAGE_SHIFT;
+        else
+            mfn = (pte & L0_PAGETABLE_MASK) >> PAGE_SHIFT;
+    }
+
+ out_unmap_pt:
+    munmap(pt, PAGE_SIZE);
+ out_unmap_pd:
+    munmap(pd, PAGE_SIZE);
+ out_unmap_pdp:
+    munmap(pdppage, PAGE_SIZE);
+ out_unmap_pml:
+    munmap(pml, PAGE_SIZE);
+ out:
+    return mfn;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-set-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */