| Message ID | 1464924384-15269-9-git-send-email-dave.long@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 2 Jun 2016 23:26:22 -0400 David Long <dave.long@linaro.org> wrote: > From: William Cohen <wcohen@redhat.com> > > The trampoline code is used by kretprobes to capture a return from a probed > function. This is done by saving the registers, calling the handler, and > restoring the registers. The code then returns to the original saved caller > return address. It is necessary to do this directly instead of using a > software breakpoint because the code used in processing that breakpoint > could itself be kprobe'd and cause a problematic reentry into the debug > exception handler. OK, I think we had discussed why this was not included to the next patch. (Not like to merge patches from different person?) Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Thanks, > Signed-off-by: William Cohen <wcohen@redhat.com> > Signed-off-by: David A. Long <dave.long@linaro.org> > --- > arch/arm64/include/asm/kprobes.h | 2 + > arch/arm64/kernel/Makefile | 1 + > arch/arm64/kernel/asm-offsets.c | 11 +++++ > arch/arm64/kernel/kprobes.c | 5 ++ > arch/arm64/kernel/kprobes_trampoline.S | 85 ++++++++++++++++++++++++++++++++++ > 5 files changed, 104 insertions(+) > create mode 100644 arch/arm64/kernel/kprobes_trampoline.S > > diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h > index 79c9511..61b4915 100644 > --- a/arch/arm64/include/asm/kprobes.h > +++ b/arch/arm64/include/asm/kprobes.h > @@ -56,5 +56,7 @@ int kprobe_exceptions_notify(struct notifier_block *self, > unsigned long val, void *data); > int kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr); > int kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr); > +void kretprobe_trampoline(void); > +void __kprobes *trampoline_probe_handler(struct pt_regs *regs); > > #endif /* _ARM_KPROBES_H */ > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > index 46724a1..75751b7 100644 > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -38,6 +38,7 @@ arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o > arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o > arm64-obj-$(CONFIG_KGDB) += kgdb.o > arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o \ > + kprobes_trampoline.o \ > probes-simulate-insn.o > arm64-obj-$(CONFIG_EFI) += efi.o efi-entry.stub.o > arm64-obj-$(CONFIG_PCI) += pci.o > diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c > index f8e5d47..03dfa27 100644 > --- a/arch/arm64/kernel/asm-offsets.c > +++ b/arch/arm64/kernel/asm-offsets.c > @@ -51,6 +51,17 @@ int main(void) > DEFINE(S_X5, offsetof(struct pt_regs, regs[5])); > DEFINE(S_X6, offsetof(struct pt_regs, regs[6])); > DEFINE(S_X7, offsetof(struct pt_regs, regs[7])); > + DEFINE(S_X8, offsetof(struct pt_regs, regs[8])); > + DEFINE(S_X10, offsetof(struct pt_regs, regs[10])); > + DEFINE(S_X12, offsetof(struct pt_regs, regs[12])); > + DEFINE(S_X14, offsetof(struct pt_regs, regs[14])); > + DEFINE(S_X16, offsetof(struct pt_regs, regs[16])); > + DEFINE(S_X18, offsetof(struct pt_regs, regs[18])); > + DEFINE(S_X20, offsetof(struct pt_regs, regs[20])); > + DEFINE(S_X22, offsetof(struct pt_regs, regs[22])); > + DEFINE(S_X24, offsetof(struct pt_regs, regs[24])); > + DEFINE(S_X26, offsetof(struct pt_regs, regs[26])); > + DEFINE(S_X28, offsetof(struct pt_regs, regs[28])); > DEFINE(S_LR, offsetof(struct pt_regs, regs[30])); > DEFINE(S_SP, offsetof(struct pt_regs, sp)); > #ifdef CONFIG_COMPAT > diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c > index 9d0ad47..b35f76f 100644 > --- a/arch/arm64/kernel/kprobes.c > +++ b/arch/arm64/kernel/kprobes.c > @@ -575,6 +575,11 @@ bool arch_within_kprobe_blacklist(unsigned long addr) > return false; > } > > +void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) > +{ > + return NULL; > +} > + > int __init arch_init_kprobes(void) > { > return 0; > diff --git a/arch/arm64/kernel/kprobes_trampoline.S b/arch/arm64/kernel/kprobes_trampoline.S > new file mode 100644 > index 0000000..ba37d85 > --- /dev/null > +++ b/arch/arm64/kernel/kprobes_trampoline.S > @@ -0,0 +1,85 @@ > +/* > + * trampoline entry and return code for kretprobes. > + */ > + > +#include <linux/linkage.h> > +#include <asm/asm-offsets.h> > +#include <asm/assembler.h> > + > + .text > + > +.macro save_all_base_regs > + stp x0, x1, [sp, #S_X0] > + stp x2, x3, [sp, #S_X2] > + stp x4, x5, [sp, #S_X4] > + stp x6, x7, [sp, #S_X6] > + stp x8, x9, [sp, #S_X8] > + stp x10, x11, [sp, #S_X10] > + stp x12, x13, [sp, #S_X12] > + stp x14, x15, [sp, #S_X14] > + stp x16, x17, [sp, #S_X16] > + stp x18, x19, [sp, #S_X18] > + stp x20, x21, [sp, #S_X20] > + stp x22, x23, [sp, #S_X22] > + stp x24, x25, [sp, #S_X24] > + stp x26, x27, [sp, #S_X26] > + stp x28, x29, [sp, #S_X28] > + add x0, sp, #S_FRAME_SIZE > + stp lr, x0, [sp, #S_LR] > +/* > + * Construct a useful saved PSTATE > + */ > + mrs x0, nzcv > + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) > + mrs x1, daif > + and x1, x1, #(PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) > + orr x0, x0, x1 > + mrs x1, CurrentEL > + and x1, x1, #(3 << 2) > + orr x0, x1, x0 > + mrs x1, SPSel > + and x1, x1, #1 > + orr x0, x1, x0 > + str x0, [sp, #S_PSTATE] > +.endm > + > +.macro restore_all_base_regs > + ldr x0, [sp, #S_PSTATE] > + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) > + msr nzcv, x0 > + ldp x0, x1, [sp, #S_X0] > + ldp x2, x3, [sp, #S_X2] > + ldp x4, x5, [sp, #S_X4] > + ldp x6, x7, [sp, #S_X6] > + ldp x8, x9, [sp, #S_X8] > + ldp x10, x11, [sp, #S_X10] > + ldp x12, x13, [sp, #S_X12] > + ldp x14, x15, [sp, #S_X14] > + ldp x16, x17, [sp, #S_X16] > + ldp x18, x19, [sp, #S_X18] > + ldp x20, x21, [sp, #S_X20] > + ldp x22, x23, [sp, #S_X22] > + ldp x24, x25, [sp, #S_X24] > + ldp x26, x27, [sp, #S_X26] > + ldp x28, x29, [sp, #S_X28] > +.endm > + > +ENTRY(kretprobe_trampoline) > + > + sub sp, sp, #S_FRAME_SIZE > + > + save_all_base_regs > + > + mov x0, sp > + bl trampoline_probe_handler > + /* Replace trampoline address in lr with actual > + orig_ret_addr return address. */ > + mov lr, x0 > + > + restore_all_base_regs > + > + add sp, sp, #S_FRAME_SIZE > + > + ret > + > +ENDPROC(kretprobe_trampoline) > -- > 2.5.0 >
On 06/07/2016 06:38 AM, Masami Hiramatsu wrote: > On Thu, 2 Jun 2016 23:26:22 -0400 > David Long <dave.long@linaro.org> wrote: > >> From: William Cohen <wcohen@redhat.com> >> >> The trampoline code is used by kretprobes to capture a return from a probed >> function. This is done by saving the registers, calling the handler, and >> restoring the registers. The code then returns to the original saved caller >> return address. It is necessary to do this directly instead of using a >> software breakpoint because the code used in processing that breakpoint >> could itself be kprobe'd and cause a problematic reentry into the debug >> exception handler. > > OK, I think we had discussed why this was not included to the next patch. > (Not like to merge patches from different person?) Yes, and adding the trampoline support before making use of it seemed OK to me even if it wasn't strictly necessary. > > Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > > Thanks, > > >> Signed-off-by: William Cohen <wcohen@redhat.com> >> Signed-off-by: David A. Long <dave.long@linaro.org> >> --- >> arch/arm64/include/asm/kprobes.h | 2 + >> arch/arm64/kernel/Makefile | 1 + >> arch/arm64/kernel/asm-offsets.c | 11 +++++ >> arch/arm64/kernel/kprobes.c | 5 ++ >> arch/arm64/kernel/kprobes_trampoline.S | 85 ++++++++++++++++++++++++++++++++++ >> 5 files changed, 104 insertions(+) >> create mode 100644 arch/arm64/kernel/kprobes_trampoline.S >> >> diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h >> index 79c9511..61b4915 100644 >> --- a/arch/arm64/include/asm/kprobes.h >> +++ b/arch/arm64/include/asm/kprobes.h >> @@ -56,5 +56,7 @@ int kprobe_exceptions_notify(struct notifier_block *self, >> unsigned long val, void *data); >> int kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr); >> int kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr); >> +void kretprobe_trampoline(void); >> +void __kprobes *trampoline_probe_handler(struct pt_regs *regs); >> >> #endif /* _ARM_KPROBES_H */ >> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile >> index 46724a1..75751b7 100644 >> --- a/arch/arm64/kernel/Makefile >> +++ b/arch/arm64/kernel/Makefile >> @@ -38,6 +38,7 @@ arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o >> arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o >> arm64-obj-$(CONFIG_KGDB) += kgdb.o >> arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o \ >> + kprobes_trampoline.o \ >> probes-simulate-insn.o >> arm64-obj-$(CONFIG_EFI) += efi.o efi-entry.stub.o >> arm64-obj-$(CONFIG_PCI) += pci.o >> diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c >> index f8e5d47..03dfa27 100644 >> --- a/arch/arm64/kernel/asm-offsets.c >> +++ b/arch/arm64/kernel/asm-offsets.c >> @@ -51,6 +51,17 @@ int main(void) >> DEFINE(S_X5, offsetof(struct pt_regs, regs[5])); >> DEFINE(S_X6, offsetof(struct pt_regs, regs[6])); >> DEFINE(S_X7, offsetof(struct pt_regs, regs[7])); >> + DEFINE(S_X8, offsetof(struct pt_regs, regs[8])); >> + DEFINE(S_X10, offsetof(struct pt_regs, regs[10])); >> + DEFINE(S_X12, offsetof(struct pt_regs, regs[12])); >> + DEFINE(S_X14, offsetof(struct pt_regs, regs[14])); >> + DEFINE(S_X16, offsetof(struct pt_regs, regs[16])); >> + DEFINE(S_X18, offsetof(struct pt_regs, regs[18])); >> + DEFINE(S_X20, offsetof(struct pt_regs, regs[20])); >> + DEFINE(S_X22, offsetof(struct pt_regs, regs[22])); >> + DEFINE(S_X24, offsetof(struct pt_regs, regs[24])); >> + DEFINE(S_X26, offsetof(struct pt_regs, regs[26])); >> + DEFINE(S_X28, offsetof(struct pt_regs, regs[28])); >> DEFINE(S_LR, offsetof(struct pt_regs, regs[30])); >> DEFINE(S_SP, offsetof(struct pt_regs, sp)); >> #ifdef CONFIG_COMPAT >> diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c >> index 9d0ad47..b35f76f 100644 >> --- a/arch/arm64/kernel/kprobes.c >> +++ b/arch/arm64/kernel/kprobes.c >> @@ -575,6 +575,11 @@ bool arch_within_kprobe_blacklist(unsigned long addr) >> return false; >> } >> >> +void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) >> +{ >> + return NULL; >> +} >> + >> int __init arch_init_kprobes(void) >> { >> return 0; >> diff --git a/arch/arm64/kernel/kprobes_trampoline.S b/arch/arm64/kernel/kprobes_trampoline.S >> new file mode 100644 >> index 0000000..ba37d85 >> --- /dev/null >> +++ b/arch/arm64/kernel/kprobes_trampoline.S >> @@ -0,0 +1,85 @@ >> +/* >> + * trampoline entry and return code for kretprobes. >> + */ >> + >> +#include <linux/linkage.h> >> +#include <asm/asm-offsets.h> >> +#include <asm/assembler.h> >> + >> + .text >> + >> +.macro save_all_base_regs >> + stp x0, x1, [sp, #S_X0] >> + stp x2, x3, [sp, #S_X2] >> + stp x4, x5, [sp, #S_X4] >> + stp x6, x7, [sp, #S_X6] >> + stp x8, x9, [sp, #S_X8] >> + stp x10, x11, [sp, #S_X10] >> + stp x12, x13, [sp, #S_X12] >> + stp x14, x15, [sp, #S_X14] >> + stp x16, x17, [sp, #S_X16] >> + stp x18, x19, [sp, #S_X18] >> + stp x20, x21, [sp, #S_X20] >> + stp x22, x23, [sp, #S_X22] >> + stp x24, x25, [sp, #S_X24] >> + stp x26, x27, [sp, #S_X26] >> + stp x28, x29, [sp, #S_X28] >> + add x0, sp, #S_FRAME_SIZE >> + stp lr, x0, [sp, #S_LR] >> +/* >> + * Construct a useful saved PSTATE >> + */ >> + mrs x0, nzcv >> + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) >> + mrs x1, daif >> + and x1, x1, #(PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) >> + orr x0, x0, x1 >> + mrs x1, CurrentEL >> + and x1, x1, #(3 << 2) >> + orr x0, x1, x0 >> + mrs x1, SPSel >> + and x1, x1, #1 >> + orr x0, x1, x0 >> + str x0, [sp, #S_PSTATE] >> +.endm >> + >> +.macro restore_all_base_regs >> + ldr x0, [sp, #S_PSTATE] >> + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) >> + msr nzcv, x0 >> + ldp x0, x1, [sp, #S_X0] >> + ldp x2, x3, [sp, #S_X2] >> + ldp x4, x5, [sp, #S_X4] >> + ldp x6, x7, [sp, #S_X6] >> + ldp x8, x9, [sp, #S_X8] >> + ldp x10, x11, [sp, #S_X10] >> + ldp x12, x13, [sp, #S_X12] >> + ldp x14, x15, [sp, #S_X14] >> + ldp x16, x17, [sp, #S_X16] >> + ldp x18, x19, [sp, #S_X18] >> + ldp x20, x21, [sp, #S_X20] >> + ldp x22, x23, [sp, #S_X22] >> + ldp x24, x25, [sp, #S_X24] >> + ldp x26, x27, [sp, #S_X26] >> + ldp x28, x29, [sp, #S_X28] >> +.endm >> + >> +ENTRY(kretprobe_trampoline) >> + >> + sub sp, sp, #S_FRAME_SIZE >> + >> + save_all_base_regs >> + >> + mov x0, sp >> + bl trampoline_probe_handler >> + /* Replace trampoline address in lr with actual >> + orig_ret_addr return address. */ >> + mov lr, x0 >> + >> + restore_all_base_regs >> + >> + add sp, sp, #S_FRAME_SIZE >> + >> + ret >> + >> +ENDPROC(kretprobe_trampoline) >> -- >> 2.5.0 >> > > Thanks, -dl
diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h index 79c9511..61b4915 100644 --- a/arch/arm64/include/asm/kprobes.h +++ b/arch/arm64/include/asm/kprobes.h @@ -56,5 +56,7 @@ int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); int kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr); int kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr); +void kretprobe_trampoline(void); +void __kprobes *trampoline_probe_handler(struct pt_regs *regs); #endif /* _ARM_KPROBES_H */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 46724a1..75751b7 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -38,6 +38,7 @@ arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o arm64-obj-$(CONFIG_KGDB) += kgdb.o arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o \ + kprobes_trampoline.o \ probes-simulate-insn.o arm64-obj-$(CONFIG_EFI) += efi.o efi-entry.stub.o arm64-obj-$(CONFIG_PCI) += pci.o diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index f8e5d47..03dfa27 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -51,6 +51,17 @@ int main(void) DEFINE(S_X5, offsetof(struct pt_regs, regs[5])); DEFINE(S_X6, offsetof(struct pt_regs, regs[6])); DEFINE(S_X7, offsetof(struct pt_regs, regs[7])); + DEFINE(S_X8, offsetof(struct pt_regs, regs[8])); + DEFINE(S_X10, offsetof(struct pt_regs, regs[10])); + DEFINE(S_X12, offsetof(struct pt_regs, regs[12])); + DEFINE(S_X14, offsetof(struct pt_regs, regs[14])); + DEFINE(S_X16, offsetof(struct pt_regs, regs[16])); + DEFINE(S_X18, offsetof(struct pt_regs, regs[18])); + DEFINE(S_X20, offsetof(struct pt_regs, regs[20])); + DEFINE(S_X22, offsetof(struct pt_regs, regs[22])); + DEFINE(S_X24, offsetof(struct pt_regs, regs[24])); + DEFINE(S_X26, offsetof(struct pt_regs, regs[26])); + DEFINE(S_X28, offsetof(struct pt_regs, regs[28])); DEFINE(S_LR, offsetof(struct pt_regs, regs[30])); DEFINE(S_SP, offsetof(struct pt_regs, sp)); #ifdef CONFIG_COMPAT diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c index 9d0ad47..b35f76f 100644 --- a/arch/arm64/kernel/kprobes.c +++ b/arch/arm64/kernel/kprobes.c @@ -575,6 +575,11 @@ bool arch_within_kprobe_blacklist(unsigned long addr) return false; } +void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) +{ + return NULL; +} + int __init arch_init_kprobes(void) { return 0; diff --git a/arch/arm64/kernel/kprobes_trampoline.S b/arch/arm64/kernel/kprobes_trampoline.S new file mode 100644 index 0000000..ba37d85 --- /dev/null +++ b/arch/arm64/kernel/kprobes_trampoline.S @@ -0,0 +1,85 @@ +/* + * trampoline entry and return code for kretprobes. + */ + +#include <linux/linkage.h> +#include <asm/asm-offsets.h> +#include <asm/assembler.h> + + .text + +.macro save_all_base_regs + stp x0, x1, [sp, #S_X0] + stp x2, x3, [sp, #S_X2] + stp x4, x5, [sp, #S_X4] + stp x6, x7, [sp, #S_X6] + stp x8, x9, [sp, #S_X8] + stp x10, x11, [sp, #S_X10] + stp x12, x13, [sp, #S_X12] + stp x14, x15, [sp, #S_X14] + stp x16, x17, [sp, #S_X16] + stp x18, x19, [sp, #S_X18] + stp x20, x21, [sp, #S_X20] + stp x22, x23, [sp, #S_X22] + stp x24, x25, [sp, #S_X24] + stp x26, x27, [sp, #S_X26] + stp x28, x29, [sp, #S_X28] + add x0, sp, #S_FRAME_SIZE + stp lr, x0, [sp, #S_LR] +/* + * Construct a useful saved PSTATE + */ + mrs x0, nzcv + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) + mrs x1, daif + and x1, x1, #(PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT) + orr x0, x0, x1 + mrs x1, CurrentEL + and x1, x1, #(3 << 2) + orr x0, x1, x0 + mrs x1, SPSel + and x1, x1, #1 + orr x0, x1, x0 + str x0, [sp, #S_PSTATE] +.endm + +.macro restore_all_base_regs + ldr x0, [sp, #S_PSTATE] + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT) + msr nzcv, x0 + ldp x0, x1, [sp, #S_X0] + ldp x2, x3, [sp, #S_X2] + ldp x4, x5, [sp, #S_X4] + ldp x6, x7, [sp, #S_X6] + ldp x8, x9, [sp, #S_X8] + ldp x10, x11, [sp, #S_X10] + ldp x12, x13, [sp, #S_X12] + ldp x14, x15, [sp, #S_X14] + ldp x16, x17, [sp, #S_X16] + ldp x18, x19, [sp, #S_X18] + ldp x20, x21, [sp, #S_X20] + ldp x22, x23, [sp, #S_X22] + ldp x24, x25, [sp, #S_X24] + ldp x26, x27, [sp, #S_X26] + ldp x28, x29, [sp, #S_X28] +.endm + +ENTRY(kretprobe_trampoline) + + sub sp, sp, #S_FRAME_SIZE + + save_all_base_regs + + mov x0, sp + bl trampoline_probe_handler + /* Replace trampoline address in lr with actual + orig_ret_addr return address. */ + mov lr, x0 + + restore_all_base_regs + + add sp, sp, #S_FRAME_SIZE + + ret + +ENDPROC(kretprobe_trampoline)