lkml.org 
[lkml]   [2017]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCHv4 3/6] powerpc64: Add .opd based function descriptor dereference
    Date
    We are moving towards separate kernel and module function descriptor
    dereference callbacks. This patch enables it for powerpc64.

    For pointers that belong to the kernel
    - Added __start_opd and __end_opd pointers, to track the kernel
    .opd section address range;

    - Added dereference_kernel_function_descriptor(). Now we
    will dereference only function pointers that are within
    [__start_opd, __end_opd);

    For pointers that belong to a module
    - Added dereference_module_function_descriptor() to handle module
    function descriptor dereference. Now we will dereference only
    pointers that are within [module->opd.start, module->opd.end).

    Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
    ---
    arch/powerpc/include/asm/module.h | 3 +++
    arch/powerpc/include/asm/sections.h | 12 ++++++++++++
    arch/powerpc/kernel/module_64.c | 14 ++++++++++++++
    arch/powerpc/kernel/vmlinux.lds.S | 2 ++
    4 files changed, 31 insertions(+)

    diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
    index 6c0132c7212f..7e28442827f1 100644
    --- a/arch/powerpc/include/asm/module.h
    +++ b/arch/powerpc/include/asm/module.h
    @@ -45,6 +45,9 @@ struct mod_arch_specific {
    unsigned long tramp;
    #endif

    + /* For module function descriptor dereference */
    + unsigned long start_opd;
    + unsigned long end_opd;
    #else /* powerpc64 */
    /* Indices of PLT sections within module. */
    unsigned int core_plt_section;
    diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
    index 82bec63bbd4f..e335a8f846af 100644
    --- a/arch/powerpc/include/asm/sections.h
    +++ b/arch/powerpc/include/asm/sections.h
    @@ -66,6 +66,9 @@ static inline int overlaps_kvm_tmp(unsigned long start, unsigned long end)
    }

    #ifdef PPC64_ELF_ABI_v1
    +
    +#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
    +
    #undef dereference_function_descriptor
    static inline void *dereference_function_descriptor(void *ptr)
    {
    @@ -76,6 +79,15 @@ static inline void *dereference_function_descriptor(void *ptr)
    ptr = p;
    return ptr;
    }
    +
    +#undef dereference_kernel_function_descriptor
    +static inline void *dereference_kernel_function_descriptor(void *ptr)
    +{
    + if (ptr < (void *)__start_opd || ptr >= (void *)__end_opd)
    + return ptr;
    +
    + return dereference_function_descriptor(ptr);
    +}
    #endif /* PPC64_ELF_ABI_v1 */

    #endif
    diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
    index 759104b99f9f..218971ac7e04 100644
    --- a/arch/powerpc/kernel/module_64.c
    +++ b/arch/powerpc/kernel/module_64.c
    @@ -93,6 +93,15 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym)
    {
    return 0;
    }
    +
    +void *dereference_module_function_descriptor(struct module *mod, void *ptr)
    +{
    + if (ptr < (void *)mod->arch.start_opd ||
    + ptr >= (void *)mod->arch.end_opd)
    + return ptr;
    +
    + return dereference_function_descriptor(ptr);
    +}
    #endif

    #define STUB_MAGIC 0x73747562 /* stub */
    @@ -344,6 +353,11 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
    else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
    dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
    sechdrs[i].sh_size);
    + else if (!strcmp(secstrings + sechdrs[i].sh_name, ".opd")) {
    + me->arch.start_opd = sechdrs[i].sh_addr;
    + me->arch.end_opd = sechdrs[i].sh_addr +
    + sechdrs[i].sh_size;
    + }

    /* We don't handle .init for the moment: rename to _init */
    while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
    diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
    index 0494e1566ee2..5dac5ab22fa2 100644
    --- a/arch/powerpc/kernel/vmlinux.lds.S
    +++ b/arch/powerpc/kernel/vmlinux.lds.S
    @@ -278,7 +278,9 @@ SECTIONS
    }

    .opd : AT(ADDR(.opd) - LOAD_OFFSET) {
    + __start_opd = .;
    *(.opd)
    + __end_opd = .;
    }

    . = ALIGN(256);
    --
    2.15.0
    \
     
     \ /
      Last update: 2017-11-10 00:52    [W:4.155 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site