Re: [PATCH] x86: unify extable_{32|64}.c

Masami Hiramatsu
2007-12-18T17:48:52Z

Hi Harvey,

Harvey Harrison wrote:
> Introduce fixup_exception() on X86_64 and use it in kprobes to
> eliminate an #ifdef.
>
> Only X86_64 needs search_extable() due to a stepping bug.

It's a good work!
If you can work on it, please add a prototype declaration of
fixup_exception() in asm-x86/uaccess_64.h too.

>
> Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
> ---
> arch/x86/kernel/kprobes.c | 12 +--------
> arch/x86/mm/Makefile_32 | 2 +-
> arch/x86/mm/Makefile_64 | 2 +-
> arch/x86/mm/extable.c | 62 +++++++++++++++++++++++++++++++++++++++++++++
> arch/x86/mm/extable_32.c | 35 -------------------------
> arch/x86/mm/extable_64.c | 34 ------------------------
> 6 files changed, 65 insertions(+), 82 deletions(-)
>
> diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
> index 1a0d96d..045a45e 100644
> --- a/arch/x86/kernel/kprobes.c
> +++ b/arch/x86/kernel/kprobes.c
> @@ -902,19 +902,9 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
> * In case the user-specified fault handler returned
> * zero, try to fix up.
> */
> -#ifdef CONFIG_X86_64
> - {
> - const struct exception_table_entry *fixup;
> - fixup = search_exception_tables(regs->ip);
> - if (fixup) {
> - regs->ip = fixup->fixup;
> - return 1;
> - }
> - }
> -#else
> if (fixup_exception(regs))
> return 1;
> -#endif
> +
> /*
> * fixup routine could not handle it,
> * Let do_page_fault() fix it.
> diff --git a/arch/x86/mm/Makefile_32 b/arch/x86/mm/Makefile_32
> index a01aca7..6a5e981 100644
> --- a/arch/x86/mm/Makefile_32
> +++ b/arch/x86/mm/Makefile_32
> @@ -2,7 +2,7 @@
> # Makefile for the linux i386-specific parts of the memory manager.
> #
>
> -obj-y := init_32.o pgtable_32.o fault_32.o ioremap_32.o extable_32.o pageattr_32.o mmap.o
> +obj-y := init_32.o pgtable_32.o fault_32.o ioremap_32.o extable.o pageattr_32.o mmap.o
>
> obj-$(CONFIG_NUMA) += discontig_32.o
> obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
> diff --git a/arch/x86/mm/Makefile_64 b/arch/x86/mm/Makefile_64
> index b5a7448..09c997f 100644
> --- a/arch/x86/mm/Makefile_64
> +++ b/arch/x86/mm/Makefile_64
> @@ -2,7 +2,7 @@
> # Makefile for the linux x86_64-specific parts of the memory manager.
> #
>
> -obj-y := init_64.o fault_64.o ioremap_64.o extable_64.o pageattr_64.o mmap.o
> +obj-y := init_64.o fault_64.o ioremap_64.o extable.o pageattr_64.o mmap.o
> obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
> obj-$(CONFIG_NUMA) += numa_64.o
> obj-$(CONFIG_K8_NUMA) += k8topology_64.o
> diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
> new file mode 100644
> index 0000000..7e8db53
> --- /dev/null
> +++ b/arch/x86/mm/extable.c
> @@ -0,0 +1,62 @@
> +#include <linux/module.h>
> +#include <linux/spinlock.h>
> +#include <asm/uaccess.h>
> +
> +
> +int fixup_exception(struct pt_regs *regs)
> +{
> + const struct exception_table_entry *fixup;
> +
> +#ifdef CONFIG_PNPBIOS
> + if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
> + extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
> + extern u32 pnp_bios_is_utter_crap;
> + pnp_bios_is_utter_crap = 1;
> + printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
> + __asm__ volatile(
> + "movl %0, %%esp\n\t"
> + "jmp *%1\n\t"
> + : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
> + panic("do_trap: can't hit this");
> + }
> +#endif
> +
> + fixup = search_exception_tables(regs->ip);
> + if (fixup) {
> + regs->ip = fixup->fixup;
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_X86_64
> +/*
> + * Need to defined our own search_extable on X86_64 to work around
> + * a B stepping K8 bug.
> + */
> +const struct exception_table_entry *
> +search_extable(const struct exception_table_entry *first,
> + const struct exception_table_entry *last,
> + unsigned long value)
> +{
> + /* B stepping K8 bug */
> + if ((value >> 32) == 0)
> + value |= 0xffffffffUL << 32;
> +
> + while (first <= last) {
> + const struct exception_table_entry *mid;
> + long diff;
> +
> + mid = (last - first) / 2 + first;
> + diff = mid->insn - value;
> + if (diff == 0)
> + return mid;
> + else if (diff < 0)
> + first = mid+1;
> + else
> + last = mid-1;
> + }
> + return NULL;
> +}
> +#endif
> diff --git a/arch/x86/mm/extable_32.c b/arch/x86/mm/extable_32.c
> deleted file mode 100644
> index 4168546..0000000
> --- a/arch/x86/mm/extable_32.c
> +++ /dev/null
> @@ -1,35 +0,0 @@
> -/*
> - * linux/arch/i386/mm/extable.c
> - */
> -
> -#include <linux/module.h>
> -#include <linux/spinlock.h>
> -#include <asm/uaccess.h>
> -
> -int fixup_exception(struct pt_regs *regs)
> -{
> - const struct exception_table_entry *fixup;
> -
> -#ifdef CONFIG_PNPBIOS
> - if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs)))
> - {
> - extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
> - extern u32 pnp_bios_is_utter_crap;
> - pnp_bios_is_utter_crap = 1;
> - printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
> - __asm__ volatile(
> - "movl %0, %%esp\n\t"
> - "jmp *%1\n\t"
> - : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
> - panic("do_trap: can't hit this");
> - }
> -#endif
> -
> - fixup = search_exception_tables(regs->ip);
> - if (fixup) {
> - regs->ip = fixup->fixup;
> - return 1;
> - }
> -
> - return 0;
> -}
> diff --git a/arch/x86/mm/extable_64.c b/arch/x86/mm/extable_64.c
> deleted file mode 100644
> index 79ac6e7..0000000
> --- a/arch/x86/mm/extable_64.c
> +++ /dev/null
> @@ -1,34 +0,0 @@
> -/*
> - * linux/arch/x86_64/mm/extable.c
> - */
> -
> -#include <linux/module.h>
> -#include <linux/spinlock.h>
> -#include <linux/init.h>
> -#include <asm/uaccess.h>
> -
> -/* Simple binary search */
> -const struct exception_table_entry *
> -search_extable(const struct exception_table_entry *first,
> - const struct exception_table_entry *last,
> - unsigned long value)
> -{
> - /* Work around a B stepping K8 bug */
> - if ((value >> 32) == 0)
> - value |= 0xffffffffUL << 32;
> -
> - while (first <= last) {
> - const struct exception_table_entry *mid;
> - long diff;
> -
> - mid = (last - first) / 2 + first;
> - diff = mid->insn - value;
> - if (diff == 0)
> - return mid;
> - else if (diff < 0)
> - first = mid+1;
> - else
> - last = mid-1;
> - }
> - return NULL;
> -}

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com, masami.hiramatsu.pt@hitachi.com