Re: [PATCH -tip tracing/kprobes 3/6] kprobes/x86: Fix to add __kprobes to in-kernel fault handing functions

Frederic Weisbecker
2009-08-30T00:50:12Z

On Thu, Aug 27, 2009 at 01:23:11PM -0400, Masami Hiramatsu wrote:
> Add __kprobes to the functions which handles in-kernel fixable page faults.
> Since kprobes can cause those in-kernel page faults by accessing kprobe data
> structures, probing those fault functions will cause fault-int3-loop
> (do_page_fault has already been marked as __kprobes).
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> ---
>
> arch/x86/mm/fault.c | 11 ++++++-----
> 1 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index bfae139..c322e59 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -38,7 +38,8 @@ enum x86_pf_error_code {
> * Returns 0 if mmiotrace is disabled, or if the fault is not
> * handled by mmiotrace:
> */
> -static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
> +static inline int __kprobes
> +kmmio_fault(struct pt_regs *regs, unsigned long addr)
> {
> if (unlikely(is_kmmio_active()))
> if (kmmio_handler(regs, addr) == 1)

I guess the problem also resides in a lot of subfunctions such as kmmio_handler
and such...

> @@ -46,7 +47,7 @@ static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
> return 0;
> }
>
> -static inline int notify_page_fault(struct pt_regs *regs)
> +static inline int __kprobes notify_page_fault(struct pt_regs *regs)
> {
> int ret = 0;
>
> @@ -239,7 +240,7 @@ void vmalloc_sync_all(void)
> *
> * Handle a fault on the vmalloc or module mapping area
> */
> -static noinline int vmalloc_fault(unsigned long address)
> +static noinline __kprobes int vmalloc_fault(unsigned long address)
> {
> unsigned long pgd_paddr;
> pmd_t *pmd_k;
> @@ -361,7 +362,7 @@ void vmalloc_sync_all(void)
> *
> * This assumes no large pages in there.
> */
> -static noinline int vmalloc_fault(unsigned long address)
> +static noinline __kprobes int vmalloc_fault(unsigned long address)
> {
> pgd_t *pgd, *pgd_ref;
> pud_t *pud, *pud_ref;
> @@ -858,7 +859,7 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte)
> * There are no security implications to leaving a stale TLB when
> * increasing the permissions on a page.
> */
> -static noinline int
> +static noinline __kprobes int
> spurious_fault(unsigned long error_code, unsigned long address)
> {
> pgd_t *pgd;
>
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America), Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com