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 v8: - Change dprintk XENLOG_DEBUG to XENLOG_ERR on dprintk. - Remove pointless parentheses on 0xdead... - Changed __INIT.. to init_or_xsplice - Added const to sort_exception_table last parameter. - Added __initconstrel #define --- xen/arch/x86/extable.c | 31 ++++++++++++++++++------------- xen/arch/x86/test/xen_hello_world_func.c | 13 +++++++++++++ xen/common/xsplice.c | 25 +++++++++++++++++++++++++ xen/include/asm-x86/uaccess.h | 2 ++ xen/include/xen/xsplice.h | 19 +++++++++++++++++++ 5 files changed, 77 insertions(+), 13 deletions(-) diff --git a/xen/arch/x86/extable.c b/xen/arch/x86/extable.c index 2a06cca..349df79 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_or_xsplice 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_or_xsplice 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_or_xsplice sort_exception_table(struct exception_table_entry *start, + const 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..2e4af9c 100644 --- a/xen/arch/x86/test/xen_hello_world_func.c +++ b/xen/arch/x86/test/xen_hello_world_func.c @@ -5,9 +5,22 @@ #include <xen/types.h> +#include <asm/uaccess.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 11b19dd..f68062f 100644 --- a/xen/common/xsplice.c +++ b/xen/common/xsplice.c @@ -533,6 +533,31 @@ 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_ERR, 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..5df26c2 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, + const struct exception_table_entry *stop); #endif /* __X86_UACCESS_H__ */ diff --git a/xen/include/xen/xsplice.h b/xen/include/xen/xsplice.h index 7f4c8f7..cbdbff1 100644 --- a/xen/include/xen/xsplice.h +++ b/xen/include/xen/xsplice.h @@ -14,6 +14,16 @@ struct xen_sysctl_xsplice_op; #include <xen/elfstructs.h> #ifdef CONFIG_XSPLICE +/* + * 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 init_or_xsplice_const +#define init_or_xsplice_constrel +#define init_or_xsplice_data +#define init_or_xsplice + /* Convenience define for printk. */ #define XSPLICE "xsplice: " /* ELF payload special section names. */ @@ -70,6 +80,15 @@ void arch_xsplice_mask(void); void arch_xsplice_unmask(void); #else +/* + * If not compiling with xSplice certain functionality should stay as + * __init. + */ +#define init_or_xsplice_const __initconst +#define init_or_xsplice_constrel __initconstrel +#define init_or_xsplice_data __initdata +#define init_or_xsplice __init + #include <xen/errno.h> /* For -ENOSYS */ static inline int xsplice_op(struct xen_sysctl_xsplice_op *op) { -- 2.5.0 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel