Re: [PATCHv2 7/8] arm64: implement ftrace with regs

[Mark Rutland <mark.rutland@arm.com>]

On Fri, Nov 15, 2019 at 07:05:39AM +0900, Itaru Kitayama wrote:
> Is this feature avail even when building kernel with Clang?

Clang doesn't currently support -fpatchable-function-entry.

Nick (Cc'd) created an LLVM bugzilla ticket for that:

  https://bugs.llvm.org/show_bug.cgi?id=43912

... though it looks like that's having database issues at the moment.

Thanks,
Mark.

> On Wed, Oct 30, 2019 at 2:01 Mark Rutland <mark.rutland@arm.com> wrote:
> 
>     From: Torsten Duwe <duwe@lst.de>
> 
>     This patch implements FTRACE_WITH_REGS for arm64, which allows a traced
>     function's arguments (and some other registers) to be captured into a
>     struct pt_regs, allowing these to be inspected and/or modified. This is
>     a building block for live-patching, where a function's arguments may be
>     forwarded to another function. This is also necessary to enable ftrace
>     and in-kernel pointer authentication at the same time, as it allows the
>     LR value to be captured and adjusted prior to signing.
> 
>     Using GCC's -fpatchable-function-entry=N option, we can have the
>     compiler insert a configurable number of NOPs between the function entry
>     point and the usual prologue. This also ensures functions are AAPCS
>     compliant (e.g. disabling inter-procedural register allocation).
> 
>     For example, with -fpatchable-function-entry=2, GCC 8.1.0 compiles the
>     following:
> 
>     | unsigned long bar(void);
>     |
>     | unsigned long foo(void)
>     | {
>     |         return bar() + 1;
>     | }
> 
>     ... to:
> 
>     | <foo>:
>     |         nop
>     |         nop
>     |         stp     x29, x30, [sp, #-16]!
>     |         mov     x29, sp
>     |         bl      0 <bar>
>     |         add     x0, x0, #0x1
>     |         ldp     x29, x30, [sp], #16
>     |         ret
> 
>     This patch builds the kernel with -fpatchable-function-entry=2,
>     prefixing each function with two NOPs. To trace a function, we replace
>     these NOPs with a sequence that saves the LR into a GPR, then calls an
>     ftrace entry assembly function which saves this and other relevant
>     registers:
> 
>     | mov   x9, x30
>     | bl    <ftrace-entry>
> 
>     Since patchable functions are AAPCS compliant (and the kernel does not
>     use x18 as a platform register), x9-x18 can be safely clobbered in the
>     patched sequence and the ftrace entry code.
> 
>     There are now two ftrace entry functions, ftrace_regs_entry (which saves
>     all GPRs), and ftrace_entry (which saves the bare minimum). A PLT is
>     allocated for each within modules.
> 
>     Signed-off-by: Torsten Duwe <duwe@suse.de>
>     [Mark: rework asm, comments, PLTs, initialization, commit message]
>     Signed-off-by: Mark Rutland <mark.rutland@arm.com>
>     Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>     Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
>     Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>
>     Cc: Catalin Marinas <catalin.marinas@arm.com>
>     Cc: Josh Poimboeuf <jpoimboe@redhat.com>
>     Cc: Julien Thierry <jthierry@redhat.com>
>     Cc: Will Deacon <will@kernel.org>
>     ---
>      arch/arm64/Kconfig               |   2 +
>      arch/arm64/Makefile              |   5 ++
>      arch/arm64/include/asm/ftrace.h  |  23 +++++++
>      arch/arm64/include/asm/module.h  |   2 +-
>      arch/arm64/kernel/entry-ftrace.S | 140
>     +++++++++++++++++++++++++++++++++++++--
>      arch/arm64/kernel/ftrace.c       |  84 +++++++++++++++++++----
>      arch/arm64/kernel/module-plts.c  |   3 +-
>      arch/arm64/kernel/module.c       |  18 +++--
>      8 files changed, 252 insertions(+), 25 deletions(-)
> 
>     diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>     index 950a56b71ff0..0ffb8596b8a1 100644
>     --- a/arch/arm64/Kconfig
>     +++ b/arch/arm64/Kconfig
>     @@ -143,6 +143,8 @@ config ARM64
>             select HAVE_DEBUG_KMEMLEAK
>             select HAVE_DMA_CONTIGUOUS
>             select HAVE_DYNAMIC_FTRACE
>     +       select HAVE_DYNAMIC_FTRACE_WITH_REGS \
>     +               if $(cc-option,-fpatchable-function-entry=2)
>             select HAVE_EFFICIENT_UNALIGNED_ACCESS
>             select HAVE_FAST_GUP
>             select HAVE_FTRACE_MCOUNT_RECORD
>     diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
>     index 2c0238ce0551..1fbe24d4fdb6 100644
>     --- a/arch/arm64/Makefile
>     +++ b/arch/arm64/Makefile
>     @@ -95,6 +95,11 @@ ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)
>      KBUILD_LDS_MODULE      += $(srctree)/arch/arm64/kernel/module.lds
>      endif
> 
>     +ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)
>     +  KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
>     +  CC_FLAGS_FTRACE := -fpatchable-function-entry=2
>     +endif
>     +
>      # Default value
>      head-y         := arch/arm64/kernel/head.o
> 
>     diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/
>     ftrace.h
>     index d48667b04c41..91fa4baa1a93 100644
>     --- a/arch/arm64/include/asm/ftrace.h
>     +++ b/arch/arm64/include/asm/ftrace.h
>     @@ -11,9 +11,20 @@
>      #include <asm/insn.h>
> 
>      #define HAVE_FUNCTION_GRAPH_FP_TEST
>     +
>     +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
>     +#define ARCH_SUPPORTS_FTRACE_OPS 1
>     +#else
>      #define MCOUNT_ADDR            ((unsigned long)_mcount)
>     +#endif
>     +
>     +/* The BL at the callsite's adjusted rec->ip */
>      #define MCOUNT_INSN_SIZE       AARCH64_INSN_SIZE
> 
>     +#define FTRACE_PLT_IDX         0
>     +#define FTRACE_REGS_PLT_IDX    1
>     +#define NR_FTRACE_PLTS         2
>     +
>      /*
>       * Currently, gcc tends to save the link register after the local
>     variables
>       * on the stack. This causes the max stack tracer to report the function
>     @@ -44,12 +55,24 @@ extern void return_to_handler(void);
>      static inline unsigned long ftrace_call_adjust(unsigned long addr)
>      {
>             /*
>     +        * Adjust addr to point at the BL in the callsite.
>     +        * See ftrace_init_nop() for the callsite sequence.
>     +        */
>     +       if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>     +               return addr + AARCH64_INSN_SIZE;
>     +       /*
>              * addr is the address of the mcount call instruction.
>              * recordmcount does the necessary offset calculation.
>              */
>             return addr;
>      }
> 
>     +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
>     +struct dyn_ftrace;
>     +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
>     +#define ftrace_init_nop ftrace_init_nop
>     +#endif
>     +
>      #define ftrace_return_address(n) return_address(n)
> 
>      /*
>     diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/
>     module.h
>     index f80e13cbf8ec..1e93de68c044 100644
>     --- a/arch/arm64/include/asm/module.h
>     +++ b/arch/arm64/include/asm/module.h
>     @@ -21,7 +21,7 @@ struct mod_arch_specific {
>             struct mod_plt_sec      init;
> 
>             /* for CONFIG_DYNAMIC_FTRACE */
>     -       struct plt_entry        *ftrace_trampoline;
>     +       struct plt_entry        *ftrace_trampolines;
>      };
>      #endif
> 
>     diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/
>     entry-ftrace.S
>     index 33d003d80121..94720388957f 100644
>     --- a/arch/arm64/kernel/entry-ftrace.S
>     +++ b/arch/arm64/kernel/entry-ftrace.S
>     @@ -7,10 +7,137 @@
>       */
> 
>      #include <linux/linkage.h>
>     +#include <asm/asm-offsets.h>
>      #include <asm/assembler.h>
>      #include <asm/ftrace.h>
>      #include <asm/insn.h>
> 
>     +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
>     +/*
>     + * Due to -fpatchable-function-entry=2, the compiler has placed two NOPs
>     before
>     + * the regular function prologue. For an enabled callsite, ftrace_init_nop
>     () and
>     + * ftrace_make_call() have patched those NOPs to:
>     + *
>     + *     MOV     X9, LR
>     + *     BL      <entry>
>     + *
>     + * ... where <entry> is either ftrace_caller or ftrace_regs_caller.
>     + *
>     + * Each instrumented function follows the AAPCS, so here x0-x8 and x19-x30
>     are
>     + * live, and x9-x18 are safe to clobber.
>     + *
>     + * We save the callsite's context into a pt_regs before invoking and
>     ftrace
>     + * callbacks. So that we can get a sensible backtrace, we create a stack
>     record
>     + * for the callsite and the ftrace entry assembly. This is not sufficient
>     for
>     + * reliable stacktrace: until we create the callsite stack record, its
>     caller
>     + * is missing from the LR and existing chain of frame records.
>     + */
>     +       .macro  ftrace_regs_entry, allregs=0
>     +       /* Make room for pt_regs, plus a callee frame */
>     +       sub     sp, sp, #(S_FRAME_SIZE + 16)
>     +
>     +       /* Save function arguments (and x9 for simplicity) */
>     +       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]
>     +
>     +       /* Optionally save the callee-saved registers, always save the FP *
>     /
>     +       .if \allregs == 1
>     +       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]
>     +       .else
>     +       str     x29, [sp, #S_FP]
>     +       .endif
>     +
>     +       /* Save the callsite's SP and LR */
>     +       add     x10, sp, #(S_FRAME_SIZE + 16)
>     +       stp     x9, x10, [sp, #S_LR]
>     +
>     +       /* Save the PC after the ftrace callsite */
>     +       str     x30, [sp, #S_PC]
>     +
>     +       /* Create a frame record for the callsite above pt_regs */
>     +       stp     x29, x9, [sp, #S_FRAME_SIZE]
>     +       add     x29, sp, #S_FRAME_SIZE
>     +
>     +       /* Create our frame record within pt_regs. */
>     +       stp     x29, x30, [sp, #S_STACKFRAME]
>     +       add     x29, sp, #S_STACKFRAME
>     +       .endm
>     +
>     +ENTRY(ftrace_regs_caller)
>     +       ftrace_regs_entry       1
>     +       b       ftrace_common
>     +ENDPROC(ftrace_regs_caller)
>     +
>     +ENTRY(ftrace_caller)
>     +       ftrace_regs_entry       0
>     +       b       ftrace_common
>     +ENDPROC(ftrace_caller)
>     +
>     +ENTRY(ftrace_common)
>     +       sub     x0, x30, #AARCH64_INSN_SIZE     // ip (callsite's BL insn)
>     +       mov     x1, x9                          // parent_ip (callsite's
>     LR)
>     +       ldr_l   x2, function_trace_op           // op
>     +       mov     x3, sp                          // regs
>     +
>     +GLOBAL(ftrace_call)
>     +       bl      ftrace_stub
>     +
>     +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>     +GLOBAL(ftrace_graph_call)              // ftrace_graph_caller();
>     +       nop                             // If enabled, this will be
>     replaced
>     +                                       // "b ftrace_graph_caller"
>     +#endif
>     +
>     +/*
>     + * At the callsite x0-x8 and x19-x30 were live. Any C code will have
>     preserved
>     + * x19-x29 per the AAPCS, and we created frame records upon entry, so we
>     need
>     + * to restore x0-x8, x29, and x30.
>     + */
>     +ftrace_common_return:
>     +       /* Restore function arguments */
>     +       ldp     x0, x1, [sp]
>     +       ldp     x2, x3, [sp, #S_X2]
>     +       ldp     x4, x5, [sp, #S_X4]
>     +       ldp     x6, x7, [sp, #S_X6]
>     +       ldr     x8, [sp, #S_X8]
>     +
>     +       /* Restore the callsite's FP, LR, PC */
>     +       ldr     x29, [sp, #S_FP]
>     +       ldr     x30, [sp, #S_LR]
>     +       ldr     x9, [sp, #S_PC]
>     +
>     +       /* Restore the callsite's SP */
>     +       add     sp, sp, #S_FRAME_SIZE + 16
>     +
>     +       ret     x9
>     +ENDPROC(ftrace_common)
>     +
>     +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>     +ENTRY(ftrace_graph_caller)
>     +       ldr     x0, [sp, #S_PC]
>     +       sub     x0, x0, #AARCH64_INSN_SIZE      // ip (callsite's BL insn)
>     +       add     x1, sp, #S_LR                   // parent_ip (callsite's
>     LR)
>     +       ldr     x2, [sp, #S_FRAME_SIZE]         // parent fp (callsite's
>     FP)
>     +       bl      prepare_ftrace_return
>     +       b       ftrace_common_return
>     +ENDPROC(ftrace_graph_caller)
>     +#else
>     +#endif
>     +
>     +#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
>     +
>      /*
>       * Gcc with -pg will put the following code in the beginning of each
>     function:
>       *      mov x0, x30
>     @@ -160,11 +287,6 @@ GLOBAL(ftrace_graph_call)          //
>     ftrace_graph_caller();
> 
>             mcount_exit
>      ENDPROC(ftrace_caller)
>     -#endif /* CONFIG_DYNAMIC_FTRACE */
>     -
>     -ENTRY(ftrace_stub)
>     -       ret
>     -ENDPROC(ftrace_stub)
> 
>      #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>      /*
>     @@ -184,7 +306,15 @@ ENTRY(ftrace_graph_caller)
> 
>             mcount_exit
>      ENDPROC(ftrace_graph_caller)
>     +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
>     +#endif /* CONFIG_DYNAMIC_FTRACE */
>     +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
>     +
>     +ENTRY(ftrace_stub)
>     +       ret
>     +ENDPROC(ftrace_stub)
> 
>     +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>      /*
>       * void return_to_handler(void)
>       *
>     diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
>     index 822718eafdb4..aea652c33a38 100644
>     --- a/arch/arm64/kernel/ftrace.c
>     +++ b/arch/arm64/kernel/ftrace.c
>     @@ -62,6 +62,19 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
>             return ftrace_modify_code(pc, 0, new, false);
>      }
> 
>     +#ifdef CONFIG_ARM64_MODULE_PLTS
>     +static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long
>     addr)
>     +{
>     +       struct plt_entry *plt = mod->arch.ftrace_trampolines;
>     +
>     +       if (addr == FTRACE_ADDR)
>     +               return &plt[FTRACE_PLT_IDX];
>     +       if (addr == FTRACE_REGS_ADDR && IS_ENABLED
>     (CONFIG_FTRACE_WITH_REGS))
>     +               return &plt[FTRACE_REGS_PLT_IDX];
>     +       return NULL;
>     +}
>     +#endif
>     +
>      /*
>       * Turn on the call to ftrace_caller() in instrumented function
>       */
>     @@ -74,19 +87,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned
>     long addr)
>             if (offset < -SZ_128M || offset >= SZ_128M) {
>      #ifdef CONFIG_ARM64_MODULE_PLTS
>                     struct module *mod;
>     -
>     -               /*
>     -                * There is only one ftrace trampoline per module. For now,
>     -                * this is not a problem since on arm64, all dynamic ftrace
>     -                * invocations are routed via ftrace_caller(). This will
>     need
>     -                * to be revisited if support for multiple ftrace entry
>     points
>     -                * is added in the future, but for now, the pr_err() below
>     -                * deals with a theoretical issue only.
>     -                */
>     -               if (addr != FTRACE_ADDR) {
>     -                       pr_err("ftrace: far branches to multiple entry
>     points unsupported inside a single module\n");
>     -                       return -EINVAL;
>     -               }
>     +               struct plt_entry *plt;
> 
>                     /*
>                      * On kernels that support module PLTs, the offset between
>     the
>     @@ -105,7 +106,13 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned
>     long addr)
>                     if (WARN_ON(!mod))
>                             return -EINVAL;
> 
>     -               addr = (unsigned long)mod->arch.ftrace_trampoline;
>     +               plt = get_ftrace_plt(mod, addr);
>     +               if (!plt) {
>     +                       pr_err("ftrace: no module PLT for %ps\n", (void *)
>     addr);
>     +                       return -EINVAL;
>     +               }
>     +
>     +               addr = (unsigned long)plt;
>      #else /* CONFIG_ARM64_MODULE_PLTS */
>                     return -EINVAL;
>      #endif /* CONFIG_ARM64_MODULE_PLTS */
>     @@ -117,6 +124,55 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned
>     long addr)
>             return ftrace_modify_code(pc, old, new, true);
>      }
> 
>     +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
>     +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
>     +                       unsigned long addr)
>     +{
>     +       unsigned long pc = rec->ip;
>     +       u32 old, new;
>     +
>     +       old = aarch64_insn_gen_branch_imm(pc, old_addr,
>     +                                         AARCH64_INSN_BRANCH_LINK);
>     +       new = aarch64_insn_gen_branch_imm(pc, addr,
>     AARCH64_INSN_BRANCH_LINK);
>     +
>     +       return ftrace_modify_code(pc, old, new, true);
>     +}
>     +
>     +/*
>     + * The compiler has inserted two NOPs before the regular function
>     prologue.
>     + * All instrumented functions follow the AAPCS, so x0-x8 and x19-x30 are
>     live,
>     + * and x9-x18 are free for our use.
>     + *
>     + * At runtime we want to be able to swing a single NOP <-> BL to enable or
>     + * disable the ftrace call. The BL requires us to save the original LR
>     value,
>     + * so here we insert a <MOV X9, LR> over the first NOP so the instructions
>     + * before the regular prologue are:
>     + *
>     + * | Compiled | Disabled   | Enabled    |
>     + * +----------+------------+------------+
>     + * | NOP      | MOV X9, LR | MOV X9, LR |
>     + * | NOP      | NOP        | BL <entry> |
>     + *
>     + * The LR value will be recovered by ftrace_regs_entry, and restored into
>     LR
>     + * before returning to the regular function prologue. When a function is
>     not
>     + * being traced, the MOV is not harmful given x9 is not live per the
>     AAPCS.
>     + *
>     + * Note: ftrace_process_locs() has pre-adjusted rec->ip to be the address
>     of
>     + * the BL.
>     + */
>     +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
>     +{
>     +       unsigned long pc = rec->ip - AARCH64_INSN_SIZE;
>     +       u32 old, new;
>     +
>     +       old = aarch64_insn_gen_nop();
>     +       new = aarch64_insn_gen_move_reg(AARCH64_INSN_REG_9,
>     +                                       AARCH64_INSN_REG_LR,
>     +                                       AARCH64_INSN_VARIANT_64BIT);
>     +       return ftrace_modify_code(pc, old, new, true);
>     +}
>     +#endif
>     +
>      /*
>       * Turn off the call to ftrace_caller() in instrumented function
>       */
>     diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/
>     module-plts.c
>     index b182442b87a3..65b08a74aec6 100644
>     --- a/arch/arm64/kernel/module-plts.c
>     +++ b/arch/arm64/kernel/module-plts.c
>     @@ -4,6 +4,7 @@
>       */
> 
>      #include <linux/elf.h>
>     +#include <linux/ftrace.h>
>      #include <linux/kernel.h>
>      #include <linux/module.h>
>      #include <linux/sort.h>
>     @@ -330,7 +331,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr
>     *sechdrs,
>                     tramp->sh_type = SHT_NOBITS;
>                     tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
>                     tramp->sh_addralign = __alignof__(struct plt_entry);
>     -               tramp->sh_size = sizeof(struct plt_entry);
>     +               tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
>             }
> 
>             return 0;
>     diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
>     index 5f5bc3b94da7..00d21a420c60 100644
>     --- a/arch/arm64/kernel/module.c
>     +++ b/arch/arm64/kernel/module.c
>     @@ -486,21 +486,31 @@ static const Elf_Shdr *find_section(const Elf_Ehdr
>     *hdr,
>             return NULL;
>      }
> 
>     +static inline void __init_plt(struct plt_entry *plt, unsigned long addr)
>     +{
>     +       *plt = get_plt_entry(addr, plt);
>     +}
>     +
>      int module_init_ftrace_plt(const Elf_Ehdr *hdr,
>                                const Elf_Shdr *sechdrs,
>                                struct module *mod)
>      {
>      #if defined(CONFIG_ARM64_MODULE_PLTS) && defined(CONFIG_DYNAMIC_FTRACE)
>             const Elf_Shdr *s;
>     -       struct plt_entry *plt;
>     +       struct plt_entry *plts;
> 
>             s = find_section(hdr, sechdrs, ".text.ftrace_trampoline");
>             if (!s)
>                     return -ENOEXEC;
> 
>     -       plt = (void *)s->sh_addr;
>     -       *plt = get_plt_entry(FTRACE_ADDR, plt);
>     -       mod->arch.ftrace_trampoline = plt;
>     +       plts = (void *)s->sh_addr;
>     +
>     +       __init_plt(&plts[FTRACE_PLT_IDX], FTRACE_ADDR);
>     +
>     +       if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
>     +               __init_plt(&plts[FTRACE_REGS_PLT_IDX], FTRACE_REGS_ADDR);
>     +
>     +       mod->arch.ftrace_trampolines = plts;
>      #endif
>             return 0;
>      }
>     --
>     2.11.0
> 
> 
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