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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] reenabling ptrace for paravirtualized guests
Here is a new version of the patch which reenables ptrace for
paravirtualized guests and enables single-stepping in GDB. Changes:
- Added to_ma function which translates a physical address to a
machine address for HVM guests and just returns the address for PV
guests.
- Use to_ma() in map_domain_va_32, map_domain_va_pae and
map_domain_va_64 to abstract away differences between HVM and PV
guests.
- Reenable single-stepping for attached domains
- (From Keir, Ryan) Export CR0 to PV guests as well.
I've removed the address checks against 0 since the last version since
physical/machine address 0 should be valid. Invalid translations
should be catched in xc_map_foreign_domain.
As before, I have not been able to test the patch on HVM, PAE or
64-bit domains and would appreciate if someone could give the patch a
try.
Signed-Off-By: Simon Kagstrom <simon.kagstrom@xxxxxx>
===File /tmp/xc_ptrace.patch================================
diff -r 5df90f95916e tools/libxc/xc_ptrace.c
--- a/tools/libxc/xc_ptrace.c Fri May 12 10:36:26 2006 +0200
+++ b/tools/libxc/xc_ptrace.c Fri May 12 11:13:14 2006 +0200
@@ -157,6 +157,27 @@ static long nr_pages
static long nr_pages = 0;
static unsigned long *page_array = NULL;
+
+/*
+ * Translates physical addresses to machine addresses for HVM
+ * guests. For paravirtual domains the function will just return the
+ * given address.
+ *
+ * This function should be used when reading page directories/page
+ * tables.
+ *
+ */
+static unsigned long
+to_ma(int cpu,
+ unsigned long in_addr)
+{
+ unsigned long maddr = in_addr;
+
+ if ( (ctxt[cpu].flags & VGCF_HVM_GUEST) && paging_enabled(&ctxt[cpu]) )
+ maddr = page_array[maddr >> PAGE_SHIFT] << PAGE_SHIFT;
+ return maddr;
+}
+
static void *
map_domain_va_32(
int xc_handle,
@@ -188,10 +209,7 @@ map_domain_va_32(
if ( cr3_virt[cpu] == NULL )
return NULL;
}
- if ( (pde = cr3_virt[cpu][vtopdi(va)]) == 0 )
- return NULL;
- if ( (ctxt[cpu].flags & VGCF_HVM_GUEST) && paging_enabled(&ctxt[cpu]) )
- pde = page_array[pde >> PAGE_SHIFT] << PAGE_SHIFT;
+ pde = to_ma(cpu, cr3_virt[cpu][vtopdi(va)]);
if ( pde != pde_phys[cpu] )
{
pde_phys[cpu] = pde;
@@ -203,10 +221,8 @@ map_domain_va_32(
if ( pde_virt[cpu] == NULL )
return NULL;
}
- if ( (page = pde_virt[cpu][vtopti(va)]) == 0 )
- return NULL;
- if (ctxt[cpu].flags & VGCF_HVM_GUEST)
- page = page_array[page >> PAGE_SHIFT] << PAGE_SHIFT;
+ page = to_ma(cpu, pde_virt[cpu][vtopti(va)]);
+
if ( (page != page_phys[cpu]) || (perm != prev_perm[cpu]) )
{
page_phys[cpu] = page;
@@ -243,25 +259,22 @@ map_domain_va_pae(
if ( l3 == NULL )
return NULL;
- l2p = l3[l3_table_offset_pae(va)] >> PAGE_SHIFT;
- l2p = page_array[l2p];
- l2 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, PROT_READ,
l2p);
+ l2p = to_ma(cpu, l3[l3_table_offset_pae(va)]);
+ l2 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, PROT_READ,
l2p >> PAGE_SHIFT);
munmap(l3, PAGE_SIZE);
if ( l2 == NULL )
return NULL;
- l1p = l2[l2_table_offset_pae(va)] >> PAGE_SHIFT;
- l1p = page_array[l1p];
- l1 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm, l1p);
+ l1p = to_ma(cpu, l2[l2_table_offset_pae(va)]);
+ l1 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm, l1p
>> PAGE_SHIFT);
munmap(l2, PAGE_SIZE);
if ( l1 == NULL )
return NULL;
- p = l1[l1_table_offset_pae(va)] >> PAGE_SHIFT;
- p = page_array[p];
+ p = to_ma(cpu, l1[l1_table_offset_pae(va)]);
if ( v != NULL )
munmap(v, PAGE_SIZE);
- v = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm, p);
+ v = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm, p >>
PAGE_SHIFT);
munmap(l1, PAGE_SIZE);
if ( v == NULL )
return NULL;
@@ -289,38 +302,35 @@ map_domain_va_64(
if ( l4 == NULL )
return NULL;
- l3p = l4[l4_table_offset(va)] >> PAGE_SHIFT;
- l3p = page_array[l3p];
- l3 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, PROT_READ,
l3p);
+ l3p = to_ma(cpu, l4[l4_table_offset(va)]);
+ l3 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, PROT_READ,
l3p >> PAGE_SHIFT);
munmap(l4, PAGE_SIZE);
if ( l3 == NULL )
return NULL;
- l2p = l3[l3_table_offset(va)] >> PAGE_SHIFT;
- l2p = page_array[l2p];
- l2 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, PROT_READ,
l2p);
+ l2p = to_ma(cpu, l3[l3_table_offset(va)]);
+ l2 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, PROT_READ,
l2p >> PAGE_SHIFT);
munmap(l3, PAGE_SIZE);
if ( l2 == NULL )
return NULL;
l1 = NULL;
- l1e = l2[l2_table_offset(va)];
+ l1e = to_ma(cpu, l2[l2_table_offset(va)]);
l1p = l1e >> PAGE_SHIFT;
if (l1e & 0x80) { /* 2M pages */
- p = (l1p + l1_table_offset(va));
+ p = to_ma(cpu, (l1p + l1_table_offset(va)) << PAGE_SHIFT);
} else { /* 4K pages */
- l1p = page_array[l1p];
- l1 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm,
l1p);
+ l1p = to_ma(cpu, l1e[l1_table_offset(va)]);
+ l1 = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm,
l1p >> PAGE_SHIFT);
munmap(l2, PAGE_SIZE);
if ( l1 == NULL )
return NULL;
- p = l1[l1_table_offset(va)] >> PAGE_SHIFT;
- }
- p = page_array[p];
+ p = to_ma(cpu, l1[l1_table_offset(va)]);
+ }
if ( v != NULL )
munmap(v, PAGE_SIZE);
- v = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm, p);
+ v = xc_map_foreign_range(xc_handle, current_domid, PAGE_SIZE, perm, p >>
PAGE_SHIFT);
if (l1)
munmap(l1, PAGE_SIZE);
if ( v == NULL )
@@ -381,7 +391,7 @@ map_domain_va(
if ( v != NULL )
munmap(v, PAGE_SIZE);
- page = page_array[va >> PAGE_SHIFT] << PAGE_SHIFT;
+ page = to_ma(cpu, page_array[va >> PAGE_SHIFT]);
v = xc_map_foreign_range( xc_handle, current_domid, PAGE_SIZE,
perm, page >> PAGE_SHIFT);
@@ -526,7 +536,7 @@ xc_ptrace(
break;
case PTRACE_SINGLESTEP:
- if (!current_isfile)
+ if (current_isfile)
goto out_unspported; /* XXX not yet supported */
/* XXX we can still have problems if the user switches threads
* during single-stepping - but that just seems retarded
diff -r 5df90f95916e xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c Fri May 12 10:36:26 2006 +0200
+++ b/xen/arch/x86/domain.c Fri May 12 11:13:14 2006 +0200
@@ -379,6 +379,9 @@ int arch_set_info_guest(
v->arch.flags |= TF_kernel_mode;
memcpy(&v->arch.guest_context, c, sizeof(*c));
+ /* Only CR0.TS is modifiable by guest or admin. */
+ v->arch.guest_context.ctrlreg[0] &= X86_CR0_TS;
+ v->arch.guest_context.ctrlreg[0] |= read_cr0() & ~X86_CR0_TS;
init_int80_direct_trap(v);
if ( !(c->flags & VGCF_HVM_GUEST) )
============================================================
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