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SubjectRe: [PATCH v2 2/4] kprobes: split blacklist into common and arch
On 04/04/2013 06:21 PM, Oskar Andero wrote:
> Some blackpoints are only valid for specific architectures. To let each
> architecture specify its own blackpoints the list has been split in two
> lists: common and arch. The common list is kept in kernel/kprobes.c and
> the arch list is kept in the arch/ directory.
>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: linux-arch@vger.kernel.org
> Signed-off-by: Oskar Andero <oskar.andero@sonymobile.com>
> ---
> arch/arc/kernel/kprobes.c | 3 ++
> arch/arm/kernel/kprobes.c | 2 +
> arch/avr32/kernel/kprobes.c | 3 ++
> arch/ia64/kernel/kprobes.c | 3 ++
> arch/mips/kernel/kprobes.c | 3 ++
> arch/mn10300/kernel/kprobes.c | 2 +
> arch/powerpc/kernel/kprobes.c | 3 ++
> arch/s390/kernel/kprobes.c | 3 ++
> arch/sh/kernel/kprobes.c | 3 ++
> arch/sparc/kernel/kprobes.c | 3 ++
> arch/x86/kernel/kprobes/core.c | 3 ++
> kernel/kprobes.c | 85 +++++++++++++++++++++++++++---------------
> 12 files changed, 86 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arc/kernel/kprobes.c b/arch/arc/kernel/kprobes.c
> index 3bfeacb..894eee6 100644
> --- a/arch/arc/kernel/kprobes.c
> +++ b/arch/arc/kernel/kprobes.c
> @@ -24,6 +24,9 @@
> DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
> DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> int __kprobes arch_prepare_kprobe(struct kprobe *p)
> {
> /* Attempt to probe at unaligned address */
> diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
> index 170e9f3..772d9ec 100644
> --- a/arch/arm/kernel/kprobes.c
> +++ b/arch/arm/kernel/kprobes.c
> @@ -46,6 +46,8 @@
> DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
> DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
>
> int __kprobes arch_prepare_kprobe(struct kprobe *p)
> {
> diff --git a/arch/avr32/kernel/kprobes.c b/arch/avr32/kernel/kprobes.c
> index f820e9f..3b02c1e 100644
> --- a/arch/avr32/kernel/kprobes.c
> +++ b/arch/avr32/kernel/kprobes.c
> @@ -24,6 +24,9 @@ static struct pt_regs jprobe_saved_regs;
>
> struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> int __kprobes arch_prepare_kprobe(struct kprobe *p)
> {
> int ret = 0;
> diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
> index f8280a7..239f2fd 100644
> --- a/arch/ia64/kernel/kprobes.c
> +++ b/arch/ia64/kernel/kprobes.c
> @@ -42,6 +42,9 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> enum instruction_type {A, I, M, F, B, L, X, u};
> static enum instruction_type bundle_encoding[32][3] = {
> { M, I, I }, /* 00 */
> diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
> index 12bc4eb..de6a1aa 100644
> --- a/arch/mips/kernel/kprobes.c
> +++ b/arch/mips/kernel/kprobes.c
> @@ -53,6 +53,9 @@ static const union mips_instruction breakpoint2_insn = {
> DEFINE_PER_CPU(struct kprobe *, current_kprobe);
> DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> static int __kprobes insn_has_delayslot(union mips_instruction insn)
> {
> switch (insn.i_format.opcode) {
> diff --git a/arch/mn10300/kernel/kprobes.c b/arch/mn10300/kernel/kprobes.c
> index 0311a7f..ed57094 100644
> --- a/arch/mn10300/kernel/kprobes.c
> +++ b/arch/mn10300/kernel/kprobes.c
> @@ -41,6 +41,8 @@ static unsigned long cur_kprobe_bp_addr;
>
> DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
>
> /* singlestep flag bits */
> #define SINGLESTEP_BRANCH 1
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index 11f5b03..b18ba45 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -47,6 +47,9 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> int __kprobes arch_prepare_kprobe(struct kprobe *p)
> {
> int ret = 0;
> diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
> index 3388b2b..2077bb0 100644
> --- a/arch/s390/kernel/kprobes.c
> +++ b/arch/s390/kernel/kprobes.c
> @@ -37,6 +37,9 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> struct kretprobe_blackpoint kretprobe_blacklist[] = { };
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
> {
> switch (insn[0] >> 8) {
> diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
> index 42b46e6..8acfb02 100644
> --- a/arch/sh/kernel/kprobes.c
> +++ b/arch/sh/kernel/kprobes.c
> @@ -24,6 +24,9 @@ static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
> static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
> static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> #define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
> #define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
> #define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
> diff --git a/arch/sparc/kernel/kprobes.c b/arch/sparc/kernel/kprobes.c
> index e722121..627e35c 100644
> --- a/arch/sparc/kernel/kprobes.c
> +++ b/arch/sparc/kernel/kprobes.c
> @@ -45,6 +45,9 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> int __kprobes arch_prepare_kprobe(struct kprobe *p)
> {
> if ((unsigned long) p->addr & 0x3UL)
> diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> index 7bfe318..4aa71a5 100644
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -65,6 +65,9 @@ void jprobe_return_end(void);
> DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
> DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>
> +const char * const arch_kprobes_blacksyms[] = {};
> +const size_t arch_kprobes_blacksyms_size = ARRAY_SIZE(arch_kprobes_blacksyms);
> +
> #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
>
> #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 0a270e5..7654278 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -68,7 +68,6 @@
> #endif
>
> static int kprobes_initialized;
> -static int kprobe_blacklist_initialized;
> static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
> static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
>
> @@ -94,31 +93,60 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
> *
> * For such cases, we now have a blacklist
> */
> -static struct kprobe_blackpoint kprobe_blacklist[] = {
> - {"preempt_schedule",},
> - {"native_get_debugreg",},
> - {"irq_entries_start",},
> - {"common_interrupt",},
> - {"mcount",}, /* mcount can be called from everywhere */
> - {NULL} /* Terminator */
> +static const char * const common_kprobes_blacksyms[] = {
> + "preempt_schedule",
> + "native_get_debugreg",
> + "irq_entries_start",
> + "common_interrupt",
> + "mcount", /* mcount can be called from everywhere */
> };
> +static const size_t common_kprobes_blacksyms_size =
> + ARRAY_SIZE(common_kprobes_blacksyms);
> +
> +extern const char * const arch_kprobes_blacksyms[];
> +extern const size_t arch_kprobes_blacksyms_size;

Instead of this, if you define arch_kprobes_blacksyms{,_size} as weak symbols
here, you don't need to patch all the arches for dummy empty entries.
Any arch which cares for a blacklist can easily override the weak def by defining
it's own copy. A lot of core kernel code - where arch variant is NOT typically use
dis written this way !

Thx,
-Vineet


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