From 757186093b40ad3b37962c34294d032b0d88739f Mon Sep 17 00:00:00 2001 From: Philipp Rudo Date: Tue, 7 Feb 2017 14:17:04 +0100 Subject: Add basic Linux kernel support This patch implements a basic target_ops for Linux kernel support. In particular it models Linux tasks as GDB threads such that you are able to change to a given thread, get backtraces, disassemble the current frame etc.. Currently the target_ops is designed only to work with static targets, i.e. dumps. Thus it lacks implementation for hooks like to_wait, to_resume or to_store_registers. Furthermore the mapping between a CPU and the task_struct of the running task is only be done once at initialization. See cover letter for a detailed discussion. Nevertheless i made some design decisions different to Peter [1] which are worth discussing. Especially storing the private data in a htab (or std::unordered_map if i had the time...) instead of global variables makes the code much nicer and less memory consuming. [1] https://sourceware.org/ml/gdb-patches/2016-12/msg00382.html gdb/ChangeLog: * gdbarch.sh (lk_init_private): New hook. * gdbarch.h: Regenerated. * gdbarch.c: Regenerated. * lk-low.h: New file. * lk-low.c: New file. * lk-lists.h: New file. * lk-lists.c: New file. * Makefile.in (SFILES, ALLDEPFILES): Add lk-low.c and lk-lists.c. (HFILES_NO_SRCDIR): Add lk-low.h and lk-lists.h. (ALL_TARGET_OBS): Add lk-low.o (COMMON_OBS): Add lk-lists.o --- gdb/Makefile.in | 8 + gdb/gdbarch.c | 31 ++ gdb/gdbarch.h | 8 + gdb/gdbarch.sh | 4 + gdb/lk-lists.c | 47 ++++ gdb/lk-lists.h | 56 ++++ gdb/lk-low.c | 860 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ gdb/lk-low.h | 309 ++++++++++++++++++++ 8 files changed, 1323 insertions(+) create mode 100644 gdb/lk-lists.c create mode 100644 gdb/lk-lists.h create mode 100644 gdb/lk-low.c create mode 100644 gdb/lk-low.h diff --git a/gdb/Makefile.in b/gdb/Makefile.in index e0fe442..41dcd4a 100644 --- a/gdb/Makefile.in +++ b/gdb/Makefile.in @@ -805,6 +805,7 @@ ALL_TARGET_OBS = \ iq2000-tdep.o \ linux-record.o \ linux-tdep.o \ + lk-low.o \ lm32-tdep.o \ m32c-tdep.o \ m32r-linux-tdep.o \ @@ -1092,6 +1093,8 @@ SFILES = \ jit.c \ language.c \ linespec.c \ + lk-lists.c \ + lk-low.c \ location.c \ m2-exp.y \ m2-lang.c \ @@ -1339,6 +1342,8 @@ HFILES_NO_SRCDIR = \ linux-nat.h \ linux-record.h \ linux-tdep.h \ + lk-lists.h \ + lk-low.h \ location.h \ m2-lang.h \ m32r-tdep.h \ @@ -1699,6 +1704,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \ jit.o \ language.o \ linespec.o \ + lk-lists.o \ location.o \ m2-lang.o \ m2-typeprint.o \ @@ -2531,6 +2537,8 @@ ALLDEPFILES = \ linux-fork.c \ linux-record.c \ linux-tdep.c \ + lk-lists.c \ + lk-low.c \ lm32-tdep.c \ m32r-linux-nat.c \ m32r-linux-tdep.c \ diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c index 266f2e9..64f6e6d 100644 --- a/gdb/gdbarch.c +++ b/gdb/gdbarch.c @@ -339,6 +339,7 @@ struct gdbarch gdbarch_gcc_target_options_ftype *gcc_target_options; gdbarch_gnu_triplet_regexp_ftype *gnu_triplet_regexp; gdbarch_addressable_memory_unit_size_ftype *addressable_memory_unit_size; + gdbarch_lk_init_private_ftype *lk_init_private; }; /* Create a new ``struct gdbarch'' based on information provided by @@ -1124,6 +1125,12 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file) "gdbarch_dump: iterate_over_regset_sections = <%s>\n", host_address_to_string (gdbarch->iterate_over_regset_sections)); fprintf_unfiltered (file, + "gdbarch_dump: gdbarch_lk_init_private_p() = %d\n", + gdbarch_lk_init_private_p (gdbarch)); + fprintf_unfiltered (file, + "gdbarch_dump: lk_init_private = <%s>\n", + host_address_to_string (gdbarch->lk_init_private)); + fprintf_unfiltered (file, "gdbarch_dump: long_bit = %s\n", plongest (gdbarch->long_bit)); fprintf_unfiltered (file, @@ -4956,6 +4963,30 @@ set_gdbarch_addressable_memory_unit_size (struct gdbarch *gdbarch, gdbarch->addressable_memory_unit_size = addressable_memory_unit_size; } +int +gdbarch_lk_init_private_p (struct gdbarch *gdbarch) +{ + gdb_assert (gdbarch != NULL); + return gdbarch->lk_init_private != NULL; +} + +void +gdbarch_lk_init_private (struct gdbarch *gdbarch) +{ + gdb_assert (gdbarch != NULL); + gdb_assert (gdbarch->lk_init_private != NULL); + if (gdbarch_debug >= 2) + fprintf_unfiltered (gdb_stdlog, "gdbarch_lk_init_private called\n"); + gdbarch->lk_init_private (gdbarch); +} + +void +set_gdbarch_lk_init_private (struct gdbarch *gdbarch, + gdbarch_lk_init_private_ftype lk_init_private) +{ + gdbarch->lk_init_private = lk_init_private; +} + /* Keep a registry of per-architecture data-pointers required by GDB modules. */ diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h index 50bc6a9..7ed2cf8 100644 --- a/gdb/gdbarch.h +++ b/gdb/gdbarch.h @@ -1545,6 +1545,14 @@ typedef int (gdbarch_addressable_memory_unit_size_ftype) (struct gdbarch *gdbarc extern int gdbarch_addressable_memory_unit_size (struct gdbarch *gdbarch); extern void set_gdbarch_addressable_memory_unit_size (struct gdbarch *gdbarch, gdbarch_addressable_memory_unit_size_ftype *addressable_memory_unit_size); +/* Initiate architecture dependent private data for the linux-kernel target. */ + +extern int gdbarch_lk_init_private_p (struct gdbarch *gdbarch); + +typedef void (gdbarch_lk_init_private_ftype) (struct gdbarch *gdbarch); +extern void gdbarch_lk_init_private (struct gdbarch *gdbarch); +extern void set_gdbarch_lk_init_private (struct gdbarch *gdbarch, gdbarch_lk_init_private_ftype *lk_init_private); + /* Definition for an unknown syscall, used basically in error-cases. */ #define UNKNOWN_SYSCALL (-1) diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh index 54549b6..e6903aa 100755 --- a/gdb/gdbarch.sh +++ b/gdb/gdbarch.sh @@ -1163,6 +1163,10 @@ m:const char *:gnu_triplet_regexp:void:::default_gnu_triplet_regexp::0 # each address in memory. m:int:addressable_memory_unit_size:void:::default_addressable_memory_unit_size::0 +# Initialize architecture dependent private data for the linux-kernel +# target. +M:void:lk_init_private:void: + EOF } diff --git a/gdb/lk-lists.c b/gdb/lk-lists.c new file mode 100644 index 0000000..55d11bd --- /dev/null +++ b/gdb/lk-lists.c @@ -0,0 +1,47 @@ +/* Iterators for internal data structures of the Linux kernel. + + Copyright (C) 2016 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include "defs.h" + +#include "inferior.h" +#include "lk-lists.h" +#include "lk-low.h" + +/* Returns next entry from struct list_head CURR while iterating field + SNAME->FNAME. */ + +CORE_ADDR +lk_list_head_next (CORE_ADDR curr, const char *sname, const char *fname) +{ + CORE_ADDR next, next_prev; + + /* We must always assume that the data we handle is corrupted. Thus use + curr->next->prev == curr as sanity check. */ + next = lk_read_addr (curr + LK_OFFSET (list_head, next)); + next_prev = lk_read_addr (next + LK_OFFSET (list_head, prev)); + + if (!curr || curr != next_prev) + { + error (_("Memory corruption detected while iterating list_head at "\ + "0x%s belonging to list %s->%s."), + phex (curr, lk_builtin_type_size (unsigned_long)) , sname, fname); + } + + return next; +} diff --git a/gdb/lk-lists.h b/gdb/lk-lists.h new file mode 100644 index 0000000..f9c2a85 --- /dev/null +++ b/gdb/lk-lists.h @@ -0,0 +1,56 @@ +/* Iterators for internal data structures of the Linux kernel. + + Copyright (C) 2016 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#ifndef __LK_LISTS_H__ +#define __LK_LISTS_H__ + +extern CORE_ADDR lk_list_head_next (CORE_ADDR curr, const char *sname, + const char *fname); + +/* Iterator over field SNAME->FNAME of type struct list_head starting at + address START of type struct list_head. This iterator is intended to be + used for lists initiated with macro LIST_HEAD (include/linux/list.h) in + the kernel, i.e. lists that START is a global variable of type struct + list_head and _not_ of type struct SNAME as the rest of the list. Thus + START will not be iterated over but only be used to start/terminate the + iteration. */ + +#define lk_list_for_each(next, start, sname, fname) \ + for ((next) = lk_list_head_next ((start), #sname, #fname); \ + (next) != (start); \ + (next) = lk_list_head_next ((next), #sname, #fname)) + +/* Iterator over struct SNAME linked together via field SNAME->FNAME of type + struct list_head starting at address START of type struct SNAME. In + contrast to the iterator above, START is a "full" member of the list and + thus will be iterated over. */ + +#define lk_list_for_each_container(cont, start, sname, fname) \ + CORE_ADDR _next; \ + bool _first_loop = true; \ + for ((cont) = (start), \ + _next = (start) + LK_OFFSET (sname, fname); \ + \ + (cont) != (start) || _first_loop; \ + \ + _next = lk_list_head_next (_next, #sname, #fname), \ + (cont) = LK_CONTAINER_OF (_next, sname, fname), \ + _first_loop = false) + +#endif /* __LK_LISTS_H__ */ diff --git a/gdb/lk-low.c b/gdb/lk-low.c new file mode 100644 index 0000000..a26373b --- /dev/null +++ b/gdb/lk-low.c @@ -0,0 +1,860 @@ +/* Basic Linux kernel support, architecture independent. + + Copyright (C) 2016 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include "defs.h" + +#include "block.h" +#include "exceptions.h" +#include "frame.h" +#include "gdbarch.h" +#include "gdbcore.h" +#include "gdbthread.h" +#include "gdbtypes.h" +#include "inferior.h" +#include "lk-lists.h" +#include "lk-low.h" +#include "objfiles.h" +#include "observer.h" +#include "solib.h" +#include "target.h" +#include "value.h" + +#include + +struct target_ops *linux_kernel_ops = NULL; + +/* Initialize a private data entry for an address, where NAME is the name + of the symbol, i.e. variable name in Linux, ALIAS the name used to + retrieve the entry from hashtab, and SILENT a flag to determine if + errors should be ignored. + + Returns a pointer to the new entry. In case of an error, either returns + NULL (SILENT = TRUE) or throws an error (SILENT = FALSE). If SILENT = TRUE + the caller is responsible to check for errors. + + Do not use directly, use LK_DECLARE_* macros defined in lk-low.h instead. */ + +struct lk_private_data * +lk_init_addr (const char *name, const char *alias, int silent) +{ + /* Initialize to NULL to silence gcc. */ + struct value *val = NULL; + struct lk_private_data *data; + void **new_slot; + void *old_slot; + + if ((old_slot = lk_find (alias)) != NULL) + return (struct lk_private_data *) old_slot; + + TRY + { + /* Choose global block for search, in case the variable was redefined + in the current context. */ + const struct block *global = block_global_block (get_selected_block (0)); + const char *tmp = name; + expression_up expr = parse_exp_1 (&tmp, 0, global, 0); + + gdb_assert (*tmp == '\0'); + val = evaluate_expression (expr.get ()); + } + CATCH (except, RETURN_MASK_ALL) + { + if (!silent) + error (_("Could not find address %s. Aborting."), alias); + + return NULL; + } + END_CATCH + + data = XCNEW (struct lk_private_data); + data->alias = alias; + data->data.addr = value_address (val); + + new_slot = lk_find_slot (alias); + *new_slot = data; + + return data; +} + +/* Same as lk_init_addr but for structs. */ + +struct lk_private_data * +lk_init_struct (const char *name, const char *alias, int silent) +{ + /* Initialize to NULL to silence GCC. */ + struct value *val = NULL; + struct lk_private_data *data; + void **new_slot; + void *old_slot; + + if ((old_slot = lk_find (alias)) != NULL) + return (struct lk_private_data *) old_slot; + + /* There are two ways to define structs + o struct name { ... }; + o typedef struct { ... } name; + Both are used in the linux kernel. Thus we have to check for both ways. + We do this by first searching for "struct name" (the "struct " is added + by macro LK_STRUCT_NAME in lk-low.h) and if not found seach for "name". + + Note: The alias will always keep its "struct "-prefix, even when + given explicitely. Besides some weird error messages this has no effect. + */ +retry: + TRY + { + /* Choose global block for search, in case the struct was redefined + in the current context. */ + const struct block *global = block_global_block(get_selected_block (0)); + const char *tmp = name; + expression_up expr = parse_exp_1 (&tmp, 0, global, 0); + + gdb_assert (*tmp == '\0'); + /* parsing just for 'name' can cause name clashes. Thus also check for + OP_TYPE. */ + if (expr->elts[0].opcode != OP_TYPE) + error ("We just need to get to the catch block"); + + val = evaluate_type (expr.get ()); + } + CATCH (except, RETURN_MASK_ALL) + { + /* 7 = strlen ("struct "). */ + if (strncmp (name, "struct ", 7) == 0) + { + name += 7; + goto retry; + } + + if (!silent) + error (_("Could not find %s. Aborting."), alias); + + return NULL; + } + END_CATCH + + data = XCNEW (struct lk_private_data); + data->alias = alias; + data->data.type = value_type (val); + + new_slot = lk_find_slot (alias); + *new_slot = data; + + return data; +} + +/* Nearly the same as lk_init_addr, with the difference that two names are + needed, i.e. the struct name S_NAME containing the field with name + F_NAME. */ + +struct lk_private_data * +lk_init_field (const char *s_name, const char *f_name, const char *alias, + int silent) +{ + struct lk_private_data *data; + struct lk_private_data *parent; + struct field *first, *last, *field; + void **new_slot; + void *old_slot; + + if ((old_slot = lk_find (alias)) != NULL) + return (struct lk_private_data *) old_slot; + + parent = lk_find (s_name); + if (parent == NULL) + { + parent = lk_init_struct (s_name, s_name, silent); + + /* Only SILENT == true needed, as otherwise lk_init_struct would throw + an error. */ + if (parent == NULL) + return NULL; + } + + first = TYPE_FIELDS (parent->data.type); + last = first + TYPE_NFIELDS (parent->data.type); + for (field = first; field < last; field ++) + { + if (streq (field->name, f_name)) + break; + } + + if (field == last) + { + if (!silent) + error (_("Could not find field %s->%s. Aborting."), s_name, f_name); + return NULL; + } + + data = XCNEW (struct lk_private_data); + data->alias = alias; + data->data.field = field; + + new_slot = lk_find_slot (alias); + *new_slot = data; + + return data; +} + +/* Map cpu number CPU to the original PTID from target beneath. */ + +static ptid_t +lk_cpu_to_old_ptid (const int cpu) +{ + struct lk_ptid_map *ptid_map; + + for (ptid_map = LK_PRIVATE->old_ptid; ptid_map; + ptid_map = ptid_map->next) + { + if (ptid_map->cpu == cpu) + return ptid_map->old_ptid; + } + + error (_("Could not map CPU %d to original PTID. Aborting."), cpu); +} + +/* Helper functions to read and return basic types at a given ADDRess. */ + +/* Read and return the integer value at address ADDR. */ + +int +lk_read_int (CORE_ADDR addr) +{ + size_t int_size = lk_builtin_type_size (int); + enum bfd_endian endian = gdbarch_byte_order (current_inferior ()->gdbarch); + return read_memory_integer (addr, int_size, endian); +} + +/* Read and return the unsigned integer value at address ADDR. */ + +unsigned int +lk_read_uint (CORE_ADDR addr) +{ + size_t uint_size = lk_builtin_type_size (unsigned_int); + enum bfd_endian endian = gdbarch_byte_order (current_inferior ()->gdbarch); + return read_memory_integer (addr, uint_size, endian); +} + +/* Read and return the long integer value at address ADDR. */ + +LONGEST +lk_read_long (CORE_ADDR addr) +{ + size_t long_size = lk_builtin_type_size (long); + enum bfd_endian endian = gdbarch_byte_order (current_inferior ()->gdbarch); + return read_memory_integer (addr, long_size, endian); +} + +/* Read and return the unsigned long integer value at address ADDR. */ + +ULONGEST +lk_read_ulong (CORE_ADDR addr) +{ + size_t ulong_size = lk_builtin_type_size (unsigned_long); + enum bfd_endian endian = gdbarch_byte_order (current_inferior ()->gdbarch); + return read_memory_unsigned_integer (addr, ulong_size, endian); +} + +/* Read and return the address value at address ADDR. */ + +CORE_ADDR +lk_read_addr (CORE_ADDR addr) +{ + return (CORE_ADDR) lk_read_ulong (addr); +} + +/* Reads a bitmap at a given ADDRess of size SIZE (in bits). Allocates and + returns an array of ulongs. The caller is responsible to free the array + after it is no longer needed. */ + +ULONGEST * +lk_read_bitmap (CORE_ADDR addr, size_t size) +{ + ULONGEST *bitmap; + size_t ulong_size, len; + + ulong_size = lk_builtin_type_size (unsigned_long); + len = LK_DIV_ROUND_UP (size, ulong_size * LK_BITS_PER_BYTE); + bitmap = XNEWVEC (ULONGEST, len); + + for (size_t i = 0; i < len; i++) + bitmap[i] = lk_read_ulong (addr + i * ulong_size); + + return bitmap; +} + +/* Return the next set bit in bitmap BITMAP of size SIZE (in bits) + starting from bit (index) BIT. Return SIZE when the end of the bitmap + was reached. To iterate over all set bits use macro + LK_BITMAP_FOR_EACH_SET_BIT defined in lk-low.h. */ + +size_t +lk_bitmap_find_next_bit (ULONGEST *bitmap, size_t size, size_t bit) +{ + size_t ulong_size, bits_per_ulong, elt; + + ulong_size = lk_builtin_type_size (unsigned_long); + bits_per_ulong = ulong_size * LK_BITS_PER_BYTE; + elt = bit / bits_per_ulong; + + while (bit < size) + { + /* FIXME: Explain why using lsb0 bit order. */ + if (bitmap[elt] & (1UL << (bit % bits_per_ulong))) + return bit; + + bit++; + if (bit % bits_per_ulong == 0) + elt++; + } + + return size; +} + +/* Returns the Hamming weight, i.e. number of set bits, of bitmap BITMAP + with size SIZE (in bits). */ + +size_t +lk_bitmap_hweight (ULONGEST *bitmap, size_t size) +{ + size_t ulong_size, bit, bits_per_ulong, elt, retval; + + ulong_size = lk_builtin_type_size (unsigned_long); + bits_per_ulong = ulong_size * LK_BITS_PER_BYTE; + elt = bit = 0; + retval = 0; + + while (bit < size) + { + if (bitmap[elt] & (1 << bit % bits_per_ulong)) + retval++; + + bit++; + if (bit % bits_per_ulong == 0) + elt++; + } + + return retval; +} + +/* Provide the per_cpu_offset of cpu CPU. See comment in lk-low.h for + details. */ + +CORE_ADDR +lk_get_percpu_offset (unsigned int cpu) +{ + size_t ulong_size = lk_builtin_type_size (unsigned_long); + CORE_ADDR percpu_elt; + + /* Give the architecture a chance to overwrite default behaviour. */ + if (LK_HOOK->get_percpu_offset) + return LK_HOOK->get_percpu_offset (cpu); + + percpu_elt = LK_ADDR (__per_cpu_offset) + (ulong_size * cpu); + return lk_read_addr (percpu_elt); +} + + +/* Test if a given task TASK is running. See comment in lk-low.h for + details. */ + +unsigned int +lk_task_running (CORE_ADDR task) +{ + ULONGEST *cpu_online_mask; + size_t size; + unsigned int cpu; + struct cleanup *old_chain; + + size = LK_BITMAP_SIZE (cpumask); + cpu_online_mask = lk_read_bitmap (LK_ADDR (cpu_online_mask), size); + old_chain = make_cleanup (xfree, cpu_online_mask); + + LK_BITMAP_FOR_EACH_SET_BIT (cpu_online_mask, size, cpu) + { + CORE_ADDR rq; + CORE_ADDR curr; + + rq = LK_ADDR (runqueues) + lk_get_percpu_offset (cpu); + curr = lk_read_addr (rq + LK_OFFSET (rq, curr)); + + if (curr == task) + break; + } + + if (cpu == size) + cpu = LK_CPU_INVAL; + + do_cleanups (old_chain); + return cpu; +} + +/* Update running tasks with information from struct rq->curr. */ + +static void +lk_update_running_tasks () +{ + ULONGEST *cpu_online_mask; + size_t size; + unsigned int cpu; + struct cleanup *old_chain; + + size = LK_BITMAP_SIZE (cpumask); + cpu_online_mask = lk_read_bitmap (LK_ADDR (cpu_online_mask), size); + old_chain = make_cleanup (xfree, cpu_online_mask); + + LK_BITMAP_FOR_EACH_SET_BIT (cpu_online_mask, size, cpu) + { + struct thread_info *tp; + CORE_ADDR rq, curr; + LONGEST pid, inf_pid; + ptid_t new_ptid, old_ptid; + + rq = LK_ADDR (runqueues) + lk_get_percpu_offset (cpu); + curr = lk_read_addr (rq + LK_OFFSET (rq, curr)); + pid = lk_read_int (curr + LK_OFFSET (task_struct, pid)); + inf_pid = current_inferior ()->pid; + + new_ptid = ptid_build (inf_pid, pid, curr); + old_ptid = lk_cpu_to_old_ptid (cpu); /* FIXME not suitable for + running targets? */ + + tp = find_thread_ptid (old_ptid); + if (tp && tp->state != THREAD_EXITED) + thread_change_ptid (old_ptid, new_ptid); + } + do_cleanups (old_chain); +} + +/* Update sleeping tasks by walking the task_structs starting from + init_task. */ + +static void +lk_update_sleeping_tasks () +{ + CORE_ADDR init_task, task, thread; + int inf_pid; + + inf_pid = current_inferior ()->pid; + init_task = LK_ADDR (init_task); + + lk_list_for_each_container (task, init_task, task_struct, tasks) + { + lk_list_for_each_container (thread, task, task_struct, thread_group) + { + int pid; + ptid_t ptid; + struct thread_info *tp; + + pid = lk_read_int (thread + LK_OFFSET (task_struct, pid)); + ptid = ptid_build (inf_pid, pid, thread); + + tp = find_thread_ptid (ptid); + if (tp == NULL || tp->state == THREAD_EXITED) + add_thread (ptid); + } + } +} + +/* Function for targets to_update_thread_list hook. */ + +static void +lk_update_thread_list (struct target_ops *target) +{ + prune_threads (); + lk_update_running_tasks (); + lk_update_sleeping_tasks (); +} + +/* Function for targets to_fetch_registers hook. */ + +static void +lk_fetch_registers (struct target_ops *target, + struct regcache *regcache, int regnum) +{ + CORE_ADDR task; + unsigned int cpu; + + task = (CORE_ADDR) ptid_get_tid (inferior_ptid); + cpu = lk_task_running (task); + + /* Let the target beneath fetch registers of running tasks. */ + if (cpu != LK_CPU_INVAL) + { + struct cleanup *old_inferior_ptid; + + old_inferior_ptid = save_inferior_ptid (); + inferior_ptid = lk_cpu_to_old_ptid (cpu); + linux_kernel_ops->beneath->to_fetch_registers (target, regcache, regnum); + do_cleanups (old_inferior_ptid); + } + else + { + struct gdbarch *gdbarch; + unsigned int i; + + LK_HOOK->get_registers (task, target, regcache, regnum); + + /* Mark all registers not found as unavailable. */ + gdbarch = get_regcache_arch (regcache); + for (i = 0; i < gdbarch_num_regs (gdbarch); i++) + { + if (regcache_register_status (regcache, i) == REG_UNKNOWN) + regcache_raw_supply (regcache, i, NULL); + } + } +} + +/* Function for targets to_pid_to_str hook. Marks running tasks with an + asterisk "*". */ + +static char * +lk_pid_to_str (struct target_ops *target, ptid_t ptid) +{ + static char buf[64]; + long pid; + CORE_ADDR task; + + pid = ptid_get_lwp (ptid); + task = (CORE_ADDR) ptid_get_tid (ptid); + + xsnprintf (buf, sizeof (buf), "PID: %5li%s, 0x%s", + pid, ((lk_task_running (task) != LK_CPU_INVAL) ? "*" : ""), + phex (task, lk_builtin_type_size (unsigned_long))); + + return buf; +} + +/* Function for targets to_thread_name hook. */ + +static const char * +lk_thread_name (struct target_ops *target, struct thread_info *ti) +{ + static char buf[LK_TASK_COMM_LEN + 1]; + char tmp[LK_TASK_COMM_LEN + 1]; + CORE_ADDR task, comm; + size_t size; + + size = std::min ((unsigned int) LK_TASK_COMM_LEN, + LK_ARRAY_LEN(LK_FIELD (task_struct, comm))); + + task = (CORE_ADDR) ptid_get_tid (ti->ptid); + comm = task + LK_OFFSET (task_struct, comm); + read_memory (comm, (gdb_byte *) tmp, size); + + xsnprintf (buf, sizeof (buf), "%-16s", tmp); + + return buf; +} + +/* Functions to initialize and free target_ops and its private data. As well + as functions for targets to_open/close/detach hooks. */ + +/* Check if OBFFILE is a Linux kernel. */ + +static int +lk_is_linux_kernel (struct objfile *objfile) +{ + int ok = 0; + + if (objfile == NULL || !(objfile->flags & OBJF_MAINLINE)) + return 0; + + ok += lookup_minimal_symbol ("linux_banner", NULL, objfile).minsym != NULL; + ok += lookup_minimal_symbol ("_stext", NULL, objfile).minsym != NULL; + ok += lookup_minimal_symbol ("_etext", NULL, objfile).minsym != NULL; + + return (ok > 2); +} + +/* Initialize struct lk_private. */ + +static void +lk_init_private () +{ + linux_kernel_ops->to_data = XCNEW (struct lk_private); + LK_PRIVATE->hooks = XCNEW (struct lk_private_hooks); + LK_PRIVATE->data = htab_create_alloc (31, (htab_hash) lk_hash_private_data, + (htab_eq) lk_private_data_eq, NULL, + xcalloc, xfree); +} + +/* Initialize architecture independent private data. Must be called + _after_ symbol tables were initialized. */ + +static void +lk_init_private_data () +{ + if (LK_PRIVATE->data != NULL) + htab_empty (LK_PRIVATE->data); + + LK_DECLARE_FIELD (task_struct, tasks); + LK_DECLARE_FIELD (task_struct, pid); + LK_DECLARE_FIELD (task_struct, tgid); + LK_DECLARE_FIELD (task_struct, thread_group); + LK_DECLARE_FIELD (task_struct, comm); + LK_DECLARE_FIELD (task_struct, thread); + + LK_DECLARE_FIELD (list_head, next); + LK_DECLARE_FIELD (list_head, prev); + + LK_DECLARE_FIELD (rq, curr); + + LK_DECLARE_FIELD (cpumask, bits); + + LK_DECLARE_ADDR (init_task); + LK_DECLARE_ADDR (runqueues); + LK_DECLARE_ADDR (__per_cpu_offset); + LK_DECLARE_ADDR (init_mm); + + LK_DECLARE_ADDR_ALIAS (__cpu_online_mask, cpu_online_mask); /* linux 4.5+ */ + LK_DECLARE_ADDR_ALIAS (cpu_online_bits, cpu_online_mask); /* linux -4.4 */ + if (LK_ADDR (cpu_online_mask) == -1) + error (_("Could not find address cpu_online_mask. Aborting.")); +} + +/* Frees the cpu to old ptid map. */ + +static void +lk_free_ptid_map () +{ + while (LK_PRIVATE->old_ptid) + { + struct lk_ptid_map *tmp; + + tmp = LK_PRIVATE->old_ptid; + LK_PRIVATE->old_ptid = tmp->next; + XDELETE (tmp); + } +} + +/* Initialize the cpu to old ptid map. Prefer the arch dependent + map_running_task_to_cpu hook if provided, else assume that the PID used + by target beneath is the same as in task_struct PID task_struct. See + comment on lk_ptid_map in lk-low.h for details. */ + +static void +lk_init_ptid_map () +{ + struct thread_info *ti; + ULONGEST *cpu_online_mask; + size_t size; + unsigned int cpu; + struct cleanup *old_chain; + + if (LK_PRIVATE->old_ptid != NULL) + lk_free_ptid_map (); + + size = LK_BITMAP_SIZE (cpumask); + cpu_online_mask = lk_read_bitmap (LK_ADDR (cpu_online_mask), size); + old_chain = make_cleanup (xfree, cpu_online_mask); + + ALL_THREADS (ti) + { + struct lk_ptid_map *ptid_map = XCNEW (struct lk_ptid_map); + CORE_ADDR rq, curr; + int pid; + + /* Give the architecture a chance to overwrite default behaviour. */ + if (LK_HOOK->map_running_task_to_cpu) + { + ptid_map->cpu = LK_HOOK->map_running_task_to_cpu (ti); + } + else + { + LK_BITMAP_FOR_EACH_SET_BIT (cpu_online_mask, size, cpu) + { + rq = LK_ADDR (runqueues) + lk_get_percpu_offset (cpu); + curr = lk_read_addr (rq + LK_OFFSET (rq, curr)); + pid = lk_read_int (curr + LK_OFFSET (task_struct, pid)); + + if (pid == ptid_get_lwp (ti->ptid)) + { + ptid_map->cpu = cpu; + break; + } + } + if (cpu == size) + error (_("Could not map thread with pid %d, lwp %lu to a cpu."), + ti->ptid.pid, ti->ptid.lwp); + } + ptid_map->old_ptid = ti->ptid; + ptid_map->next = LK_PRIVATE->old_ptid; + LK_PRIVATE->old_ptid = ptid_map; + } + + do_cleanups (old_chain); +} + +/* Initializes all private data and pushes the linux kernel target, if not + already done. */ + +static void +lk_try_push_target () +{ + struct gdbarch *gdbarch; + + gdbarch = current_inferior ()->gdbarch; + if (!(gdbarch && gdbarch_lk_init_private_p (gdbarch))) + error (_("Linux kernel debugging not supported on %s."), + gdbarch_bfd_arch_info (gdbarch)->printable_name); + + lk_init_private (); + lk_init_private_data (); + gdbarch_lk_init_private (gdbarch); + /* Check for required arch hooks. */ + gdb_assert (LK_HOOK->get_registers); + + lk_init_ptid_map (); + lk_update_thread_list (linux_kernel_ops); + + if (!target_is_pushed (linux_kernel_ops)) + push_target (linux_kernel_ops); +} + +/* Function for targets to_open hook. */ + +static void +lk_open (const char *args, int from_tty) +{ + struct objfile *objfile; + + if (target_is_pushed (linux_kernel_ops)) + { + printf_unfiltered (_("Linux kernel target already pushed. Aborting\n")); + return; + } + + for (objfile = current_program_space->objfiles; objfile; + objfile = objfile->next) + { + if (lk_is_linux_kernel (objfile) + && ptid_get_pid (inferior_ptid) != 0) + { + lk_try_push_target (); + return; + } + } + printf_unfiltered (_("Could not find a valid Linux kernel object file. " + "Aborting.\n")); +} + +/* Function for targets to_close hook. Deletes all private data. */ + +static void +lk_close (struct target_ops *ops) +{ + htab_delete (LK_PRIVATE->data); + lk_free_ptid_map (); + XDELETE (LK_PRIVATE->hooks); + + XDELETE (LK_PRIVATE); + linux_kernel_ops->to_data = NULL; +} + +/* Function for targets to_detach hook. */ + +static void +lk_detach (struct target_ops *t, const char *args, int from_tty) +{ + struct target_ops *beneath = linux_kernel_ops->beneath; + + unpush_target (linux_kernel_ops); + reinit_frame_cache (); + if (from_tty) + printf_filtered (_("Linux kernel target detached.\n")); + + beneath->to_detach (beneath, args, from_tty); +} + +/* Function for new objfile observer. */ + +static void +lk_observer_new_objfile (struct objfile *objfile) +{ + if (lk_is_linux_kernel (objfile) + && ptid_get_pid (inferior_ptid) != 0) + lk_try_push_target (); +} + +/* Function for inferior created observer. */ + +static void +lk_observer_inferior_created (struct target_ops *ops, int from_tty) +{ + struct objfile *objfile; + + if (ptid_get_pid (inferior_ptid) == 0) + return; + + for (objfile = current_inferior ()->pspace->objfiles; objfile; + objfile = objfile->next) + { + if (lk_is_linux_kernel (objfile)) + { + lk_try_push_target (); + return; + } + } +} + +/* Initialize linux kernel target. */ + +static void +init_linux_kernel_ops (void) +{ + struct target_ops *t; + + if (linux_kernel_ops != NULL) + return; + + t = XCNEW (struct target_ops); + t->to_shortname = "linux-kernel"; + t->to_longname = "linux kernel support"; + t->to_doc = "Adds support to debug the Linux kernel"; + + /* set t->to_data = struct lk_private in lk_init_private. */ + + t->to_open = lk_open; + t->to_close = lk_close; + t->to_detach = lk_detach; + t->to_fetch_registers = lk_fetch_registers; + t->to_update_thread_list = lk_update_thread_list; + t->to_pid_to_str = lk_pid_to_str; + t->to_thread_name = lk_thread_name; + + t->to_stratum = thread_stratum; + t->to_magic = OPS_MAGIC; + + linux_kernel_ops = t; + + add_target (t); +} + +/* Provide a prototype to silence -Wmissing-prototypes. */ +extern initialize_file_ftype _initialize_linux_kernel; + +void +_initialize_linux_kernel (void) +{ + init_linux_kernel_ops (); + + observer_attach_new_objfile (lk_observer_new_objfile); + observer_attach_inferior_created (lk_observer_inferior_created); +} diff --git a/gdb/lk-low.h b/gdb/lk-low.h new file mode 100644 index 0000000..e644ffe --- /dev/null +++ b/gdb/lk-low.h @@ -0,0 +1,309 @@ +/* Basic Linux kernel support, architecture independent. + + Copyright (C) 2016 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#ifndef __LK_LOW_H__ +#define __LK_LOW_H__ + +#include "target.h" + +extern struct target_ops *linux_kernel_ops; + +/* Copy constants defined in Linux kernel. */ +#define LK_TASK_COMM_LEN 16 +#define LK_BITS_PER_BYTE 8 + +/* Definitions used in linux kernel target. */ +#define LK_CPU_INVAL -1U + +/* Private data structs for this target. */ +/* Forward declarations. */ +struct lk_private_hooks; +struct lk_ptid_map; + +/* Short hand access to private data. */ +#define LK_PRIVATE ((struct lk_private *) linux_kernel_ops->to_data) +#define LK_HOOK (LK_PRIVATE->hooks) + +struct lk_private +{ + /* Hashtab for needed addresses, structs and fields. */ + htab_t data; + + /* Linked list to map between cpu number and original ptid from target + beneath. */ + struct lk_ptid_map *old_ptid; + + /* Hooks for architecture dependent functions. */ + struct lk_private_hooks *hooks; +}; + +/* We use the following convention for PTIDs: + + ptid->pid = inferiors PID + ptid->lwp = PID from task_stuct + ptid->tid = address of task_struct + + The task_structs address as TID has two reasons. First, we need it quite + often and there is no other reasonable way to pass it down. Second, it + helps us to distinguish swapper tasks as they all have PID = 0. + + Furthermore we cannot rely on the target beneath to use the same PID as the + task_struct. Thus we need a mapping between our PTID and the PTID of the + target beneath. Otherwise it is impossible to pass jobs, e.g. fetching + registers of running tasks, to the target beneath. */ + +/* Private data struct to map between our and the target beneath PTID. */ + +struct lk_ptid_map +{ + struct lk_ptid_map *next; + unsigned int cpu; + ptid_t old_ptid; +}; + +/* Private data struct to be stored in hashtab. */ + +struct lk_private_data +{ + const char *alias; + + union + { + CORE_ADDR addr; + struct type *type; + struct field *field; + } data; +}; + +/* Wrapper for htab_hash_string to work with our private data. */ + +static inline hashval_t +lk_hash_private_data (const struct lk_private_data *entry) +{ + return htab_hash_string (entry->alias); +} + +/* Function for htab_eq to work with our private data. */ + +static inline int +lk_private_data_eq (const struct lk_private_data *entry, + const struct lk_private_data *element) +{ + return streq (entry->alias, element->alias); +} + +/* Wrapper for htab_find_slot to work with our private data. Do not use + directly, use the macros below instead. */ + +static inline void ** +lk_find_slot (const char *alias) +{ + const struct lk_private_data dummy = { alias }; + return htab_find_slot (LK_PRIVATE->data, &dummy, INSERT); +} + +/* Wrapper for htab_find to work with our private data. Do not use + directly, use the macros below instead. */ + +static inline struct lk_private_data * +lk_find (const char *alias) +{ + const struct lk_private_data dummy = { alias }; + return (struct lk_private_data *) htab_find (LK_PRIVATE->data, &dummy); +} + +/* Functions to initialize private data. Do not use directly, use the + macros below instead. */ + +extern struct lk_private_data *lk_init_addr (const char *name, + const char *alias, int silent); +extern struct lk_private_data *lk_init_struct (const char *name, + const char *alias, int silent); +extern struct lk_private_data *lk_init_field (const char *s_name, + const char *f_name, + const char *alias, int silent); + +/* The names we use to store our private data in the hashtab. */ + +#define LK_STRUCT_NAME(s_name) ("struct " #s_name) +#define LK_FIELD_NAME(s_name, f_name) (#s_name " " #f_name) + +/* Macros to initiate addresses and fields, where (S_/F_)NAME is the variables + name as used in Linux. LK_DECLARE_FIELD also initializes the corresponding + struct entry. Throws an error, if no symbol with the given name is found. + */ + +#define LK_DECLARE_ADDR(name) \ + lk_init_addr (#name, #name, 0) +#define LK_DECLARE_FIELD(s_name, f_name) \ + lk_init_field (LK_STRUCT_NAME (s_name), #f_name,\ + LK_FIELD_NAME (s_name, f_name), 0) + +/* Same as LK_DECLARE_*, but returns NULL instead of throwing an error if no + symbol was found. The caller is responsible to check for possible errors. + */ + +#define LK_DECLARE_ADDR_SILENT(name) \ + lk_init_addr (#name, #name, 1) +#define LK_DECLARE_FIELD_SILENT(s_name, f_name) \ + lk_init_field (LK_STRUCT_NAME (s_name), #f_name,\ + LK_FIELD_NAME (s_name, f_name), 1) + +/* Same as LK_DECLARE_*_SILENT, but allows you to give an ALIAS name. If used + for a struct, the struct has to be declared explicitly _before_ any of its + fields. They are ment to be used, when a variable in the kernel was simply + renamed (at least from our point of view). The caller is responsible to + check for possible errors. */ + +#define LK_DECLARE_ADDR_ALIAS(name, alias) \ + lk_init_addr (#name, #alias, 1) +#define LK_DECLARE_STRUCT_ALIAS(s_name, alias) \ + lk_init_struct (LK_STRUCT_NAME(s_name), LK_STRUCT_NAME (alias), 1) +#define LK_DECLARE_FIELD_ALIAS(s_alias, f_name, f_alias) \ + lk_init_field (LK_STRUCT_NAME (s_alias), #f_name, \ + LK_FIELD_NAME (s_alias, f_alias), 1) + +/* Macros to retrieve private data from hashtab. Returns NULL (-1) if no entry + with the given ALIAS exists. The caller only needs to check for possible + errors if not done so at initialization. */ + +#define LK_ADDR(alias) \ + (lk_find (#alias) ? (lk_find (#alias))->data.addr : -1) +#define LK_STRUCT(alias) \ + (lk_find (LK_STRUCT_NAME (alias)) \ + ? (lk_find (LK_STRUCT_NAME (alias)))->data.type \ + : NULL) +#define LK_FIELD(s_alias, f_alias) \ + (lk_find (LK_FIELD_NAME (s_alias, f_alias)) \ + ? (lk_find (LK_FIELD_NAME (s_alias, f_alias)))->data.field \ + : NULL) + + +/* Definitions for architecture dependent hooks. */ +/* Hook to read registers from the target and supply their content + to the regcache. */ +typedef void (*lk_hook_get_registers) (CORE_ADDR task, + struct target_ops *target, + struct regcache *regcache, + int regnum); + +/* Hook to return the per_cpu_offset of cpu CPU. Only architectures that + do not use the __per_cpu_offset array to determin the offset have to + supply this hook. */ +typedef CORE_ADDR (*lk_hook_get_percpu_offset) (unsigned int cpu); + +/* Hook to map a running task to a logical CPU. Required if the target + beneath uses a different PID as struct rq. */ +typedef unsigned int (*lk_hook_map_running_task_to_cpu) (struct thread_info *ti); + +struct lk_private_hooks +{ + /* required */ + lk_hook_get_registers get_registers; + + /* optional, required if __per_cpu_offset array is not used to determine + offset. */ + lk_hook_get_percpu_offset get_percpu_offset; + + /* optional, required if the target beneath uses a different PID as struct + rq. */ + lk_hook_map_running_task_to_cpu map_running_task_to_cpu; +}; + +/* Helper functions to read and return a value at a given ADDRess. */ +extern int lk_read_int (CORE_ADDR addr); +extern unsigned int lk_read_uint (CORE_ADDR addr); +extern LONGEST lk_read_long (CORE_ADDR addr); +extern ULONGEST lk_read_ulong (CORE_ADDR addr); +extern CORE_ADDR lk_read_addr (CORE_ADDR addr); + +/* Reads a bitmap at a given ADDRess of size SIZE (in bits). Allocates and + returns an array of ulongs. The caller is responsible to free the array + after it is no longer needed. */ +extern ULONGEST *lk_read_bitmap (CORE_ADDR addr, size_t size); + +/* Walks the bitmap BITMAP of size SIZE from bit (index) BIT. + Returns the index of the next set bit or SIZE, when the end of the bitmap + was reached. To iterate over all set bits use macro + LK_BITMAP_FOR_EACH_SET_BIT defined below. */ +extern size_t lk_bitmap_find_next_bit (ULONGEST *bitmap, size_t bit, + size_t size); +#define LK_BITMAP_FOR_EACH_SET_BIT(bitmap, size, bit) \ + for ((bit) = lk_bitmap_find_next_bit ((bitmap), (size), 0); \ + (bit) < (size); \ + (bit) = lk_bitmap_find_next_bit ((bitmap), (size), (bit) + 1)) + +/* Returns the size of BITMAP in bits. */ +#define LK_BITMAP_SIZE(bitmap) \ + (FIELD_SIZE (LK_FIELD (bitmap, bits)) * LK_BITS_PER_BYTE) + +/* Returns the Hamming weight, i.e. number of set bits, of bitmap BITMAP with + size SIZE (in bits). */ +extern size_t lk_bitmap_hweight (ULONGEST *bitmap, size_t size); + + +/* Short hand access to current gdbarchs builtin types and their + size (in byte). For TYPE replace spaces " " by underscore "_", e.g. + "unsigned int" => "unsigned_int". */ +#define lk_builtin_type(type) \ + (builtin_type (current_inferior ()->gdbarch)->builtin_##type) +#define lk_builtin_type_size(type) \ + (lk_builtin_type (type)->length) + +/* If field FIELD is an array returns its length (in #elements). */ +#define LK_ARRAY_LEN(field) \ + (FIELD_SIZE (field) / FIELD_TARGET_SIZE (field)) + +/* Short hand access to the offset of field F_NAME in struct S_NAME. */ +#define LK_OFFSET(s_name, f_name) \ + (FIELD_OFFSET (LK_FIELD (s_name, f_name))) + +/* Returns the container of field FNAME of struct SNAME located at address + ADDR. */ +#define LK_CONTAINER_OF(addr, sname, fname) \ + ((addr) - LK_OFFSET (sname, fname)) + +/* Divides numinator N by demoniator D and rounds up the result. */ +#define LK_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d)) + + +/* Additional access macros to fields in the style of gdbtypes.h */ +/* Returns the size of field FIELD (in bytes). If FIELD is an array returns + the size of the whole array. */ +#define FIELD_SIZE(field) \ + TYPE_LENGTH (check_typedef (FIELD_TYPE (*field))) + +/* Returns the size of the target type of field FIELD (in bytes). If FIELD is + an array returns the size of its elements. */ +#define FIELD_TARGET_SIZE(field) \ + TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (FIELD_TYPE (*field)))) + +/* Returns the offset of field FIELD (in bytes). */ +#define FIELD_OFFSET(field) \ + (FIELD_BITPOS (*field) / TARGET_CHAR_BIT) + +/* Provides the per_cpu_offset of cpu CPU. If the architecture + provides a get_percpu_offset hook, the call is passed to it. Otherwise + returns the __per_cpu_offset[CPU] element. */ +extern CORE_ADDR lk_get_percpu_offset (unsigned int cpu); + +/* Tests if a given task TASK is running. Returns either the cpu-id + if running or LK_CPU_INVAL if not. */ +extern unsigned int lk_task_running (CORE_ADDR task); +#endif /* __LK_LOW_H__ */ -- cgit v1.1