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authorJulian Brown <julian@codesourcery.com>2009-07-30 23:05:05 +0000
committerJulian Brown <julian@codesourcery.com>2009-07-30 23:05:05 +0000
commitcca44b1b87795e0a92ec8d016456941a7986d107 (patch)
tree01563daf73571b24cef602e0c0cb619d6409520a /gdb/arm-linux-tdep.c
parent929dfd4f59cd5f4f3a135325c48d4ad9828aaf0f (diff)
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* arm-linux-tdep.c (arch-utils.h, inferior.h, gdbthread.h, symfile.h):
Include files. (arm_linux_cleanup_svc, arm_linux_copy_svc): New. (cleanup_kernel_helper_return, arm_catch_kernel_helper_return): New. (arm_linux_displaced_step_copy_insn): New. (arm_linux_init_abi): Initialise displaced stepping callbacks. * arm-tdep.c (DISPLACED_STEPPING_ARCH_VERSION): New macro. (ARM_NOP): New. (displaced_read_reg, displaced_in_arm_mode, branch_write_pc) (bx_write_pc, load_write_pc, alu_write_pc, displaced_write_reg) (insn_references_pc, copy_unmodified, cleanup_preload, copy_preload) (copy_preload_reg, cleanup_copro_load_store, copy_copro_load_store) (cleanup_branch, copy_b_bl_blx, copy_bx_blx_reg, cleanup_alu_imm) (copy_alu_imm, cleanup_alu_reg, copy_alu_reg) (cleanup_alu_shifted_reg, copy_alu_shifted_reg, cleanup_load) (cleanup_store, copy_extra_ld_st, copy_ldr_str_ldrb_strb) (cleanup_block_load_all, cleanup_block_store_pc) (cleanup_block_load_pc, copy_block_xfer, cleanup_svc, copy_svc) (copy_undef, copy_unpred): New. (decode_misc_memhint_neon, decode_unconditional) (decode_miscellaneous, decode_dp_misc, decode_ld_st_word_ubyte) (decode_media, decode_b_bl_ldmstm, decode_ext_reg_ld_st) (decode_svc_copro, arm_process_displaced_insn) (arm_displaced_init_closure, arm_displaced_step_copy_insn) (arm_displaced_step_fixup): New. (arm_gdbarch_init): Initialise max insn length field. * arm-tdep.h (DISPLACED_TEMPS, DISPLACED_MODIFIED_INSNS): New macros. (displaced_step_closure, pc_write_style): New. (arm_displaced_init_closure, displaced_read_reg) (arm_process_displaced_insn, arm_displaced_init_closure) (displaced_read_reg, displaced_write_reg, arm_displaced_step_copy_insn) (arm_displaced_step_fixup): Add prototypes.
Diffstat (limited to 'gdb/arm-linux-tdep.c')
-rw-r--r--gdb/arm-linux-tdep.c216
1 files changed, 216 insertions, 0 deletions
diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index 20419cb..beb4ecf 100644
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -38,6 +38,10 @@
#include "arm-linux-tdep.h"
#include "linux-tdep.h"
#include "glibc-tdep.h"
+#include "arch-utils.h"
+#include "inferior.h"
+#include "gdbthread.h"
+#include "symfile.h"
#include "gdb_string.h"
@@ -597,6 +601,210 @@ arm_linux_software_single_step (struct frame_info *frame)
return 1;
}
+/* Support for displaced stepping of Linux SVC instructions. */
+
+static void
+arm_linux_cleanup_svc (struct gdbarch *gdbarch ATTRIBUTE_UNUSED,
+ struct regcache *regs,
+ struct displaced_step_closure *dsc)
+{
+ CORE_ADDR from = dsc->insn_addr;
+ ULONGEST apparent_pc;
+ int within_scratch;
+
+ regcache_cooked_read_unsigned (regs, ARM_PC_REGNUM, &apparent_pc);
+
+ within_scratch = (apparent_pc >= dsc->scratch_base
+ && apparent_pc < (dsc->scratch_base
+ + DISPLACED_MODIFIED_INSNS * 4 + 4));
+
+ if (debug_displaced)
+ {
+ fprintf_unfiltered (gdb_stdlog, "displaced: PC is apparently %.8lx after "
+ "SVC step ", (unsigned long) apparent_pc);
+ if (within_scratch)
+ fprintf_unfiltered (gdb_stdlog, "(within scratch space)\n");
+ else
+ fprintf_unfiltered (gdb_stdlog, "(outside scratch space)\n");
+ }
+
+ if (within_scratch)
+ displaced_write_reg (regs, dsc, ARM_PC_REGNUM, from + 4, BRANCH_WRITE_PC);
+}
+
+static int
+arm_linux_copy_svc (struct gdbarch *gdbarch, uint32_t insn, CORE_ADDR to,
+ struct regcache *regs, struct displaced_step_closure *dsc)
+{
+ CORE_ADDR from = dsc->insn_addr;
+ struct frame_info *frame;
+ unsigned int svc_number = displaced_read_reg (regs, from, 7);
+
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: copying Linux svc insn %.8lx\n",
+ (unsigned long) insn);
+
+ frame = get_current_frame ();
+
+ /* Is this a sigreturn or rt_sigreturn syscall? Note: these are only useful
+ for EABI. */
+ if (svc_number == 119 || svc_number == 173)
+ {
+ if (get_frame_type (frame) == SIGTRAMP_FRAME)
+ {
+ CORE_ADDR return_to;
+ struct symtab_and_line sal;
+
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: found "
+ "sigreturn/rt_sigreturn SVC call. PC in frame = %lx\n",
+ (unsigned long) get_frame_pc (frame));
+
+ return_to = frame_unwind_caller_pc (frame);
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: unwind pc = %lx. "
+ "Setting momentary breakpoint.\n", (unsigned long) return_to);
+
+ gdb_assert (inferior_thread ()->step_resume_breakpoint == NULL);
+
+ sal = find_pc_line (return_to, 0);
+ sal.pc = return_to;
+ sal.section = find_pc_overlay (return_to);
+ sal.explicit_pc = 1;
+
+ frame = get_prev_frame (frame);
+
+ if (frame)
+ {
+ inferior_thread ()->step_resume_breakpoint
+ = set_momentary_breakpoint (gdbarch, sal, get_frame_id (frame),
+ bp_step_resume);
+
+ /* We need to make sure we actually insert the momentary
+ breakpoint set above. */
+ insert_breakpoints ();
+ }
+ else if (debug_displaced)
+ fprintf_unfiltered (gdb_stderr, "displaced: couldn't find previous "
+ "frame to set momentary breakpoint for "
+ "sigreturn/rt_sigreturn\n");
+ }
+ else if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: sigreturn/rt_sigreturn "
+ "SVC call not in signal trampoline frame\n");
+ }
+
+ /* Preparation: If we detect sigreturn, set momentary breakpoint at resume
+ location, else nothing.
+ Insn: unmodified svc.
+ Cleanup: if pc lands in scratch space, pc <- insn_addr + 4
+ else leave pc alone. */
+
+ dsc->modinsn[0] = insn;
+
+ dsc->cleanup = &arm_linux_cleanup_svc;
+ /* Pretend we wrote to the PC, so cleanup doesn't set PC to the next
+ instruction. */
+ dsc->wrote_to_pc = 1;
+
+ return 0;
+}
+
+
+/* The following two functions implement single-stepping over calls to Linux
+ kernel helper routines, which perform e.g. atomic operations on architecture
+ variants which don't support them natively.
+
+ When this function is called, the PC will be pointing at the kernel helper
+ (at an address inaccessible to GDB), and r14 will point to the return
+ address. Displaced stepping always executes code in the copy area:
+ so, make the copy-area instruction branch back to the kernel helper (the
+ "from" address), and make r14 point to the breakpoint in the copy area. In
+ that way, we regain control once the kernel helper returns, and can clean
+ up appropriately (as if we had just returned from the kernel helper as it
+ would have been called from the non-displaced location). */
+
+static void
+cleanup_kernel_helper_return (struct gdbarch *gdbarch ATTRIBUTE_UNUSED,
+ struct regcache *regs,
+ struct displaced_step_closure *dsc)
+{
+ displaced_write_reg (regs, dsc, ARM_LR_REGNUM, dsc->tmp[0], CANNOT_WRITE_PC);
+ displaced_write_reg (regs, dsc, ARM_PC_REGNUM, dsc->tmp[0], BRANCH_WRITE_PC);
+}
+
+static void
+arm_catch_kernel_helper_return (struct gdbarch *gdbarch, CORE_ADDR from,
+ CORE_ADDR to, struct regcache *regs,
+ struct displaced_step_closure *dsc)
+{
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+
+ dsc->numinsns = 1;
+ dsc->insn_addr = from;
+ dsc->cleanup = &cleanup_kernel_helper_return;
+ /* Say we wrote to the PC, else cleanup will set PC to the next
+ instruction in the helper, which isn't helpful. */
+ dsc->wrote_to_pc = 1;
+
+ /* Preparation: tmp[0] <- r14
+ r14 <- <scratch space>+4
+ *(<scratch space>+8) <- from
+ Insn: ldr pc, [r14, #4]
+ Cleanup: r14 <- tmp[0], pc <- tmp[0]. */
+
+ dsc->tmp[0] = displaced_read_reg (regs, from, ARM_LR_REGNUM);
+ displaced_write_reg (regs, dsc, ARM_LR_REGNUM, (ULONGEST) to + 4,
+ CANNOT_WRITE_PC);
+ write_memory_unsigned_integer (to + 8, 4, byte_order, from);
+
+ dsc->modinsn[0] = 0xe59ef004; /* ldr pc, [lr, #4]. */
+}
+
+/* Linux-specific displaced step instruction copying function. Detects when
+ the program has stepped into a Linux kernel helper routine (which must be
+ handled as a special case), falling back to arm_displaced_step_copy_insn()
+ if it hasn't. */
+
+static struct displaced_step_closure *
+arm_linux_displaced_step_copy_insn (struct gdbarch *gdbarch,
+ CORE_ADDR from, CORE_ADDR to,
+ struct regcache *regs)
+{
+ struct displaced_step_closure *dsc
+ = xmalloc (sizeof (struct displaced_step_closure));
+
+ /* Detect when we enter an (inaccessible by GDB) Linux kernel helper, and
+ stop at the return location. */
+ if (from > 0xffff0000)
+ {
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: detected kernel helper "
+ "at %.8lx\n", (unsigned long) from);
+
+ arm_catch_kernel_helper_return (gdbarch, from, to, regs, dsc);
+ }
+ else
+ {
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+ uint32_t insn = read_memory_unsigned_integer (from, 4, byte_order);
+
+ if (debug_displaced)
+ fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx "
+ "at %.8lx\n", (unsigned long) insn,
+ (unsigned long) from);
+
+ /* Override the default handling of SVC instructions. */
+ dsc->u.svc.copy_svc_os = arm_linux_copy_svc;
+
+ arm_process_displaced_insn (gdbarch, insn, from, to, regs, dsc);
+ }
+
+ arm_displaced_init_closure (gdbarch, from, to, dsc);
+
+ return dsc;
+}
+
static void
arm_linux_init_abi (struct gdbarch_info info,
struct gdbarch *gdbarch)
@@ -657,6 +865,14 @@ arm_linux_init_abi (struct gdbarch_info info,
arm_linux_regset_from_core_section);
set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type);
+
+ /* Displaced stepping. */
+ set_gdbarch_displaced_step_copy_insn (gdbarch,
+ arm_linux_displaced_step_copy_insn);
+ set_gdbarch_displaced_step_fixup (gdbarch, arm_displaced_step_fixup);
+ set_gdbarch_displaced_step_free_closure (gdbarch,
+ simple_displaced_step_free_closure);
+ set_gdbarch_displaced_step_location (gdbarch, displaced_step_at_entry_point);
}
/* Provide a prototype to silence -Wmissing-prototypes. */