From: Ross Lagerwall <ross.lagerw...@citrix.com>
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.
To not grow the code-base if xSplice is not compiled in we add
certain #define to help in determining if code needs to be __init
or not.
Signed-off-by: Ross Lagerwall <ross.lagerw...@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>
---
Cc: Keir Fraser <k...@xen.org>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Andrew Cooper <andrew.coop...@citrix.com>
v3:
- s/module/payload/
- sanity checks.
- Move code around.
- s/module/payload/
v4: Use 'struct virtual_region'
v5:
- Expand test-case.
- Deal with struct exception_table_entry being const.
v6:
- Make the code have __init if not compiled with xSplice
- Remove not needed declarations.
v7:
- Make the non_canonical_addr be 0xdead000000000000ULL
- Remove casts
- Add Reviewed-by from Andrew
- Change ifdef to be !ARM
---
---
xen/arch/x86/extable.c | 31 ++++++++++++++++++-------------
xen/arch/x86/test/xen_hello_world_func.c | 11 +++++++++++
xen/common/xsplice.c | 25 +++++++++++++++++++++++++
xen/include/asm-x86/uaccess.h | 2 ++
xen/include/xen/xsplice.h | 17 +++++++++++++++++
5 files changed, 73 insertions(+), 13 deletions(-)
diff --git a/xen/arch/x86/extable.c b/xen/arch/x86/extable.c
index 2a06cca..e0ba35f 100644
--- a/xen/arch/x86/extable.c
+++ b/xen/arch/x86/extable.c
@@ -7,6 +7,7 @@
#include <xen/spinlock.h>
#include <asm/uaccess.h>
#include <xen/virtual_region.h>
+#include <xen/xsplice.h>
#define EX_FIELD(ptr, field) ((unsigned long)&(ptr)->field + (ptr)->field)
@@ -20,7 +21,7 @@ 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 __INIT 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 +36,7 @@ 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 __INIT swap_ex(void *a, void *b, int size)
{
struct exception_table_entry *l = a, *r = b, tmp;
long delta = b - a;
@@ -48,19 +49,23 @@ static void __init swap_ex(void *a, void *b, int size)
}
#endif
-void __init sort_exception_tables(void)
+void __INIT 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 +90,7 @@ search_exception_table(unsigned long addr)
const struct virtual_region *region = find_text_region(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 +99,7 @@ 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_func.c
b/xen/arch/x86/test/xen_hello_world_func.c
index 1ad002a..432954f 100644
--- a/xen/arch/x86/test/xen_hello_world_func.c
+++ b/xen/arch/x86/test/xen_hello_world_func.c
@@ -5,9 +5,20 @@
#include <xen/types.h>
+static unsigned long *non_canonical_addr = (unsigned long
*)(0xdead000000000000ULL);
+
/* Our replacement function for xen_extra_version. */
const char *xen_hello_world(void)
{
+ unsigned long tmp;
+ int rc;
+ /*
+ * Any BUG, or WARN_ON will contain symbol and payload name. Furthermore
+ * exceptions will be caught and processed properly.
+ */
+ rc = __get_user(tmp, non_canonical_addr);
+ BUG_ON(rc != -EFAULT);
+
return "Hello World";
}
diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c
index 8424c0f..c7f70c3 100644
--- a/xen/common/xsplice.c
+++ b/xen/common/xsplice.c
@@ -529,6 +529,31 @@ static int prepare_payload(struct payload *payload,
sizeof(*region->frame[i].bugs);
}
+#ifndef CONFIG_ARM
+ sec = xsplice_elf_sec_by_name(elf, ".ex_table");
+ if ( sec )
+ {
+ struct exception_table_entry *s, *e;
+
+ if ( !sec->sec->sh_size ||
+ (sec->sec->sh_size % sizeof(*region->ex)) )
+ {
+ dprintk(XENLOG_DEBUG, XSPLICE "%s: Wrong size of .ex_table
(exp:%lu vs %lu)!\n",
+ elf->name, sizeof(*region->ex),
+ sec->sec->sh_size);
+ return -EINVAL;
+ }
+
+ s = sec->load_addr;
+ e = sec->load_addr + sec->sec->sh_size;
+
+ sort_exception_table(s ,e);
+
+ region->ex = s;
+ region->ex_end = e;
+ }
+#endif
+
return 0;
}
diff --git a/xen/include/asm-x86/uaccess.h b/xen/include/asm-x86/uaccess.h
index 947470d..2c839a9 100644
--- a/xen/include/asm-x86/uaccess.h
+++ b/xen/include/asm-x86/uaccess.h
@@ -277,5 +277,7 @@ extern struct exception_table_entry __stop___pre_ex_table[];
extern unsigned long search_exception_table(unsigned long);
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__ */
diff --git a/xen/include/xen/xsplice.h b/xen/include/xen/xsplice.h
index 3ab3911..93b3374 100644
--- a/xen/include/xen/xsplice.h
+++ b/xen/include/xen/xsplice.h
@@ -54,6 +54,15 @@ struct xsplice_patch_func_internal {
};
#endif
+/*
+ * We use alternative and exception table code - which by default are __init
+ * only, however we need them during runtime. These macros allows us to build
+ * the image with these functions built-in. (See the #else below).
+ */
+#define __INITCONST
+#define __INITDATA
+#define __INIT
+
/* Convenience define for printk. */
#define XSPLICE "xsplice: "
@@ -112,6 +121,14 @@ void arch_xsplice_mask(void);
void arch_xsplice_unmask(void);
#else
+/*
+ * If not compiling with xSplice certain functionality should stay as
+ * __init.
+ */
+#define __INITCONST __initconst
+#define __INITDATA __initdata
+#define __INIT __init
+
#include <xen/errno.h> /* For -ENOSYS */
static inline int xsplice_op(struct xen_sysctl_xsplice_op *op)
{
--
2.5.0
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