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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v5 17/28] xsplice: Add support for exception tables.
From: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Add support for exception tables contained within xSplice payloads. If an
exception occurs search either the main exception table or a particular
active payload's exception table depending on the instruction pointer.
Also we add an test-case to make sure we have an exception that
is handled.
Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
v3:
- s/module/payload/
- sanity checks.
- Move code around.
- s/module/payload/
v4: Use 'struct virtual_region'
v5:
- Expand test-case.
---
xen/arch/x86/extable.c | 30 +++++++++++++++++-------------
xen/arch/x86/test/xen_hello_world.c | 11 +++++++++++
xen/common/xsplice.c | 19 +++++++++++++++++++
xen/include/asm-x86/uaccess.h | 5 +++++
4 files changed, 52 insertions(+), 13 deletions(-)
diff --git a/xen/arch/x86/extable.c b/xen/arch/x86/extable.c
index c6c367a..a7f0144 100644
--- a/xen/arch/x86/extable.c
+++ b/xen/arch/x86/extable.c
@@ -20,7 +20,7 @@ static inline unsigned long ex_cont(const struct
exception_table_entry *x)
return EX_FIELD(x, cont);
}
-static int __init cmp_ex(const void *a, const void *b)
+static int cmp_ex(const void *a, const void *b)
{
const struct exception_table_entry *l = a, *r = b;
unsigned long lip = ex_addr(l);
@@ -35,7 +35,7 @@ static int __init cmp_ex(const void *a, const void *b)
}
#ifndef swap_ex
-static void __init swap_ex(void *a, void *b, int size)
+static void swap_ex(void *a, void *b, int size)
{
struct exception_table_entry *l = a, *r = b, tmp;
long delta = b - a;
@@ -48,19 +48,23 @@ static void __init swap_ex(void *a, void *b, int size)
}
#endif
-void __init sort_exception_tables(void)
+void sort_exception_table(struct exception_table_entry *start,
+ struct exception_table_entry *stop)
{
- sort(__start___ex_table, __stop___ex_table - __start___ex_table,
- sizeof(struct exception_table_entry), cmp_ex, swap_ex);
- sort(__start___pre_ex_table,
- __stop___pre_ex_table - __start___pre_ex_table,
+ sort(start, stop - start,
sizeof(struct exception_table_entry), cmp_ex, swap_ex);
}
-static inline unsigned long
-search_one_table(const struct exception_table_entry *first,
- const struct exception_table_entry *last,
- unsigned long value)
+void __init sort_exception_tables(void)
+{
+ sort_exception_table(__start___ex_table, __stop___ex_table);
+ sort_exception_table(__start___pre_ex_table, __stop___pre_ex_table);
+}
+
+unsigned long
+search_one_extable(const struct exception_table_entry *first,
+ const struct exception_table_entry *last,
+ unsigned long value)
{
const struct exception_table_entry *mid;
long diff;
@@ -85,7 +89,7 @@ search_exception_table(unsigned long addr)
struct virtual_region *region = search_for_text(addr);
if ( region && region->ex )
- return search_one_table(region->ex, region->ex_end-1, addr);
+ return search_one_extable(region->ex, region->ex_end-1, addr);
return 0;
}
@@ -94,7 +98,7 @@ unsigned long
search_pre_exception_table(struct cpu_user_regs *regs)
{
unsigned long addr = (unsigned long)regs->eip;
- unsigned long fixup = search_one_table(
+ unsigned long fixup = search_one_extable(
__start___pre_ex_table, __stop___pre_ex_table-1, addr);
if ( fixup )
{
diff --git a/xen/arch/x86/test/xen_hello_world.c
b/xen/arch/x86/test/xen_hello_world.c
index 5364114..0f26b06 100644
--- a/xen/arch/x86/test/xen_hello_world.c
+++ b/xen/arch/x86/test/xen_hello_world.c
@@ -12,6 +12,7 @@
static char xen_hello_world_name[] = "xen_hello_world";
extern const char *xen_hello_world(void);
+static unsigned long *non_canonical_addr = (unsigned long *)(1UL<<48);
/* External symbol. */
extern const char *xen_extra_version(void);
@@ -26,10 +27,20 @@ void apply_hook(void)
void revert_hook(void)
{
+ unsigned long tmp = 0xdeadbeef;
+ int rc;
+
printk(KERN_DEBUG "Hook unloaded.\n");
/* The hook is called _after_ the unpatching. */
if ( !strcmp(xen_extra_version(), "Hello World") )
BUG();
+ /*
+ * But before unregistering the virtual region. Which means any
+ * BUG, or WARN_ON will contain symbol name. And also exceptions
+ * will be caught and processed properly.
+ */
+ rc = __get_user(tmp, non_canonical_addr);
+ BUG_ON(rc != -EFAULT);
}
XSPLICE_LOAD_HOOK(apply_hook);
diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c
index 7b92602..4548b8b 100644
--- a/xen/common/xsplice.c
+++ b/xen/common/xsplice.c
@@ -573,6 +573,25 @@ static int prepare_payload(struct payload *payload,
region->frame[i].n_bugs = sec->sec->sh_size / sizeof(struct bug_frame);
}
+#ifdef CONFIG_X86
+ sec = xsplice_elf_sec_by_name(elf, ".ex_table");
+ if ( sec )
+ {
+ if ( !sec->sec->sh_size ||
+ (sec->sec->sh_size % sizeof (struct exception_table_entry)) )
+ {
+ dprintk(XENLOG_DEBUG, "%s%s: Wrong size of .ex_table (exp:%lu vs
%lu)!\n",
+ XSPLICE, elf->name, sizeof (struct exception_table_entry),
+ sec->sec->sh_size);
+ return -EINVAL;
+ }
+
+ region->ex = (struct exception_table_entry *)sec->load_addr;
+ region->ex_end = (struct exception_table_entry *)(sec->load_addr +
sec->sec->sh_size);
+
+ sort_exception_table(region->ex, region->ex_end);
+ }
+#endif
return 0;
}
diff --git a/xen/include/asm-x86/uaccess.h b/xen/include/asm-x86/uaccess.h
index 947470d..9e67bf0 100644
--- a/xen/include/asm-x86/uaccess.h
+++ b/xen/include/asm-x86/uaccess.h
@@ -276,6 +276,11 @@ extern struct exception_table_entry
__start___pre_ex_table[];
extern struct exception_table_entry __stop___pre_ex_table[];
extern unsigned long search_exception_table(unsigned long);
+extern unsigned long search_one_extable(const struct exception_table_entry
*first,
+ const struct exception_table_entry
*last,
+ unsigned long value);
extern void sort_exception_tables(void);
+extern void sort_exception_table(struct exception_table_entry *start,
+ struct exception_table_entry *stop);
#endif /* __X86_UACCESS_H__ */
--
2.5.0
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