From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca (simark.ca [158.69.221.121]) by sourceware.org (Postfix) with ESMTPS id DB86A396DC1A for ; Thu, 14 May 2020 15:09:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org DB86A396DC1A Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=simark.ca Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=simark@simark.ca Received: from [10.0.0.193] (unknown [192.222.164.54]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id 32F901ED39; Thu, 14 May 2020 11:09:09 -0400 (EDT) Subject: Re: [PATCH v2 3/4] arc: Add GNU/Linux support for ARC To: Shahab Vahedi , gdb-patches@sourceware.org Cc: Shahab Vahedi , Anton Kolesov , Tom Tromey , Francois Bedard References: <20200326125206.13120-1-shahab.vahedi@gmail.com> <20200428160437.1585-1-shahab.vahedi@gmail.com> <20200428160437.1585-4-shahab.vahedi@gmail.com> From: Simon Marchi Message-ID: <6f07f665-a003-5dad-bace-bfdcbd77a906@simark.ca> Date: Thu, 14 May 2020 11:09:08 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200428160437.1585-4-shahab.vahedi@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: tl Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-6.4 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, KAM_STOCKGEN, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 May 2020 15:09:11 -0000 On 2020-04-28 12:04 p.m., Shahab Vahedi via Gdb-patches wrote: > +/* Implement the "breakpoint_kind_from_pc" gdbarch method. */ > + > +static int > +arc_linux_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr) > +{ > + return 2; What is 2? > +} > + > +/* Implement the "sw_breakpoint_from_kind" gdbarch method. */ > + > +static const gdb_byte * > +arc_linux_sw_breakpoint_from_kind (struct gdbarch *gdbarch, > + int kind, int *size) > +{ > + *size = kind; > + return ((gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG) > + ? arc_linux_trap_s_be > + : arc_linux_trap_s_le); > +} > + > +/* Implement the "software_single_step" gdbarch method. */ > + > +static std::vector > +arc_linux_software_single_step (struct regcache *regcache) > +{ > + struct gdbarch *gdbarch = regcache->arch (); > + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); > + struct disassemble_info di = arc_disassemble_info (gdbarch); > + > + /* Read current instruction. */ > + struct arc_instruction curr_insn; > + arc_insn_decode (regcache_read_pc (regcache), &di, arc_delayed_print_insn, > + &curr_insn); > + CORE_ADDR next_pc = arc_insn_get_linear_next_pc (curr_insn); > + > + std::vector next_pcs; > + > + /* For instructions with delay slots, the fall thru is not the > + instruction immediately after the current instruction, but the one > + after that. */ > + if (curr_insn.has_delay_slot) > + { > + struct arc_instruction next_insn; > + arc_insn_decode (next_pc, &di, arc_delayed_print_insn, &next_insn); > + next_pcs.push_back (arc_insn_get_linear_next_pc (next_insn)); > + } > + else > + { > + next_pcs.push_back (next_pc); > + } Remove curly braces here. > + > + ULONGEST status32; > + regcache_cooked_read_unsigned (regcache, gdbarch_ps_regnum (gdbarch), > + &status32); > + > + if (curr_insn.is_control_flow) > + { > + CORE_ADDR branch_pc = arc_insn_get_branch_target (curr_insn); > + if (branch_pc != next_pc) > + next_pcs.push_back (branch_pc); > + } > + /* Is current instruction the last in a loop body? */ > + else if (tdep->has_hw_loops) > + { > + /* If STATUS32.L is 1, then ZD-loops are disabled. */ > + if ((status32 & ARC_STATUS32_L_MASK) == 0) > + { > + ULONGEST lp_end, lp_start, lp_count; > + regcache_cooked_read_unsigned (regcache, ARC_LP_START_REGNUM, > + &lp_start); > + regcache_cooked_read_unsigned (regcache, ARC_LP_END_REGNUM, &lp_end); > + regcache_cooked_read_unsigned (regcache, ARC_LP_COUNT_REGNUM, > + &lp_count); > + > + if (arc_debug) > + { > + debug_printf ("arc-linux: lp_start = %s, lp_end = %s, " > + "lp_count = %s, next_pc = %s\n", > + paddress (gdbarch, lp_start), > + paddress (gdbarch, lp_end), > + pulongest (lp_count), > + paddress (gdbarch, next_pc)); > + } > + > + if (next_pc == lp_end && lp_count > 1) > + { > + /* The instruction is in effect a jump back to the start of > + the loop. */ > + next_pcs.push_back (lp_start); > + } > + > + } > + } > + > + /* Is this a delay slot? Then next PC is in BTA register. */ > + if ((status32 & ARC_STATUS32_DE_MASK) != 0) > + { > + ULONGEST bta; > + regcache_cooked_read_unsigned (regcache, ARC_BTA_REGNUM, &bta); > + next_pcs.push_back (bta); > + } > + > + return next_pcs; > +} > + > +/* Implement the "skip_solib_resolver" gdbarch method. > + > + See glibc_skip_solib_resolver for details. */ > + > +static CORE_ADDR > +arc_linux_skip_solib_resolver (struct gdbarch *gdbarch, CORE_ADDR pc) > +{ > + /* For uClibc 0.9.26+. > + > + An unresolved PLT entry points to "__dl_linux_resolve", which calls > + "_dl_linux_resolver" to do the resolving and then eventually jumps to > + the function. > + > + So we look for the symbol `_dl_linux_resolver', and if we are there, > + gdb sets a breakpoint at the return address, and continues. */ > + struct bound_minimal_symbol resolver = > + lookup_minimal_symbol ("_dl_linux_resolver", NULL, NULL); > + > + if (arc_debug) > + { > + if (resolver.minsym) > + { > + CORE_ADDR res_addr = BMSYMBOL_VALUE_ADDRESS (resolver); > + debug_printf ("arc-linux: skip_solib_resolver (): " > + "pc = %s, resolver at %s\n", > + print_core_address (gdbarch, pc), > + print_core_address (gdbarch, res_addr)); > + } > + else > + { > + debug_printf ("arc-linux: skip_solib_resolver (): " > + "pc = %s, no resolver found\n", > + print_core_address (gdbarch, pc)); > + } > + } > + > + if (resolver.minsym && BMSYMBOL_VALUE_ADDRESS (resolver) == pc) > + { > + /* Find the return address. */ > + return frame_unwind_caller_pc (get_current_frame ()); > + } > + else > + { > + /* No breakpoint required. */ > + return 0; > + } > +} > + > +/* Initialization specific to Linux environment. */ > + > +static void > +arc_linux_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch) > +{ > + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); > + > + if (arc_debug) > + debug_printf ("arc-linux: GNU/Linux OS/ABI initialization.\n"); > + > + /* If we are using Linux, we have in uClibc > + (libc/sysdeps/linux/arc/bits/setjmp.h): > + > + typedef int __jmp_buf[13+1+1+1]; //r13-r25, fp, sp, blink > + > + Where "blink" is a stored PC of a caller function. > + */ > + tdep->jb_pc = 15; I don't really understand this, could you dumb it down a bit for me? > +/* Suppress warning from -Wmissing-prototypes. */ > +extern initialize_file_ftype _initialize_arc_linux_tdep; > + > +void > +_initialize_arc_linux_tdep (void) Remove the void. Simon