From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: [PATCH v2 12/13] xsplice: Add support for exception tables. (v2) Date: Thu, 14 Jan 2016 16:47:10 -0500 Message-ID: <1452808031-706-13-git-send-email-konrad.wilk@oracle.com> References: <1452808031-706-1-git-send-email-konrad.wilk@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aJpjt-0006Ru-HV for xen-devel@lists.xenproject.org; Thu, 14 Jan 2016 21:47:29 +0000 In-Reply-To: <1452808031-706-1-git-send-email-konrad.wilk@oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xenproject.org, ross.lagerwall@citrix.com, mpohlack@amazon.com, andrew.cooper3@citrix.com, stefano.stabellini@citrix.com, jbeulich@suse.com, ian.jackson@eu.citrix.com, ian.campbell@citrix.com, wei.liu2@citrix.com, sasha.levin@oracle.com Cc: Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org From: Ross Lagerwall 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. Signed-off-by: Ross Lagerwall Signed-off-by: Konrad Rzeszutek Wilk --- v2: - s/module/payload/ - sanity checks. --- xen/arch/x86/extable.c | 36 +++++++++++++++++++++-------------- xen/common/xsplice.c | 44 +++++++++++++++++++++++++++++++++++++++++++ xen/include/asm-x86/uaccess.h | 5 +++++ xen/include/xen/xsplice.h | 5 +++++ 4 files changed, 76 insertions(+), 14 deletions(-) diff --git a/xen/arch/x86/extable.c b/xen/arch/x86/extable.c index 89b5bcb..2787a92 100644 --- a/xen/arch/x86/extable.c +++ b/xen/arch/x86/extable.c @@ -4,6 +4,7 @@ #include #include #include +#include #include #define EX_FIELD(ptr, field) ((unsigned long)&(ptr)->field + (ptr)->field) @@ -18,7 +19,7 @@ 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); @@ -33,7 +34,7 @@ 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; @@ -46,19 +47,23 @@ 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; @@ -80,15 +85,18 @@ search_one_table(const struct exception_table_entry *first, unsigned long search_exception_table(unsigned long addr) { - return search_one_table( - __start___ex_table, __stop___ex_table-1, addr); + if ( likely(is_kernel(addr)) ) + return search_one_extable( + __start___ex_table, __stop___ex_table-1, addr); + else + return search_module_extables(addr); } 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/common/xsplice.c b/xen/common/xsplice.c index 02cb4a8..53a67a9 100644 --- a/xen/common/xsplice.c +++ b/xen/common/xsplice.c @@ -47,6 +47,10 @@ struct payload { size_t core_text_size; /* Everything else - .data,.rodata, etc. */ struct bug_frame *start_bug_frames[BUGFRAME_NR]; /* .bug.frame patching. */ struct bug_frame *stop_bug_frames[BUGFRAME_NR]; +#ifdef CONFIG_X86 + struct exception_table_entry *start_ex_table; + struct exception_table_entry *stop_ex_table; +#endif char name[XEN_XSPLICE_NAME_SIZE + 1];/* Name of it. */ }; @@ -668,6 +672,20 @@ static int find_special_sections(struct payload *payload, payload->start_bug_frames[i] = (struct bug_frame *)sec->load_addr; payload->stop_bug_frames[i] = (struct bug_frame *)(sec->load_addr + sec->sec->sh_size); } +#ifdef CONFIG_X86 + sec = xsplice_elf_sec_by_name(elf, ".ex_table"); + if ( sec ) + { + if ( ( !sec->sec->sh_size ) || + ( sec->sec->sh_size % sizeof *sec->load_addr ) ) + return -EINVAL; + + payload->start_ex_table = (struct exception_table_entry *)sec->load_addr; + payload->stop_ex_table = (struct exception_table_entry *)(sec->load_addr + sec->sec->sh_size); + + sort_exception_table(payload->start_ex_table, payload->stop_ex_table); + } +#endif return 0; } @@ -1029,6 +1047,32 @@ bool_t is_active_module_text(unsigned long addr) return 0; } +#ifdef CONFIG_X86 +unsigned long search_module_extables(unsigned long addr) +{ + struct payload *data; + unsigned long ret; + + /* No locking since this list is only ever changed during apply or revert + * context. */ + list_for_each_entry ( data, &applied_list, applied_list ) + { + if ( !data->start_ex_table ) + continue; + if ( !((void *)addr >= data->payload_address && + (void *)addr < (data->payload_address + data->core_text_size))) + continue; + + ret = search_one_extable(data->start_ex_table, data->stop_ex_table - 1, + addr); + if ( ret ) + return ret; + } + + return 0; +} +#endif + static int __init xsplice_init(void) { register_keyhandler('x', xsplice_printall, "print xsplicing info", 1); 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__ */ diff --git a/xen/include/xen/xsplice.h b/xen/include/xen/xsplice.h index 41b738a..ec929fd 100644 --- a/xen/include/xen/xsplice.h +++ b/xen/include/xen/xsplice.h @@ -29,6 +29,7 @@ void do_xsplice(void); struct bug_frame *xsplice_find_bug(const char *eip, int *id); bool_t is_module(const void *addr); bool_t is_active_module_text(unsigned long addr); +unsigned long search_module_extables(unsigned long addr); #else static inline void do_xsplice(void) { }; static inline struct bug_frame *xsplice_find_bug(const char *eip, int *id) @@ -43,6 +44,10 @@ static inline bool_t is_active_module_text(unsigned long addr) { return 0; } +static inline unsigned long search_module_extables(unsigned long addr) +{ + return 0; +} #endif /* Arch hooks */ -- 2.1.0