From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5305 invoked by alias); 4 Dec 2008 15:29:06 -0000 Received: (qmail 5294 invoked by uid 22791); 4 Dec 2008 15:29:05 -0000 X-Spam-Check-By: sourceware.org Received: from mel.act-europe.fr (HELO mel.act-europe.fr) (212.99.106.210) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 04 Dec 2008 15:28:30 +0000 Received: from localhost (localhost [127.0.0.1]) by filtered-smtp.eu.adacore.com (Postfix) with ESMTP id C8942290004 for ; Thu, 4 Dec 2008 16:28:27 +0100 (CET) Received: from mel.act-europe.fr ([127.0.0.1]) by localhost (smtp.eu.adacore.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8I9siFVHJnCW for ; Thu, 4 Dec 2008 16:28:26 +0100 (CET) Received: from province.act-europe.fr (province.act-europe.fr [10.10.0.214]) by mel.act-europe.fr (Postfix) with ESMTP id F02A929004A for ; Thu, 4 Dec 2008 16:28:26 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by filtered-province.act-europe.fr (Postfix) with ESMTP id CA77C165B7A for ; Thu, 4 Dec 2008 16:28:26 +0100 (CET) Received: from province.act-europe.fr ([127.0.0.1]) by localhost (province.act-europe.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Z3bEbLnl+zQS for ; Thu, 4 Dec 2008 16:28:26 +0100 (CET) Received: from [IPv6:::1] (province.act-europe.fr [10.10.0.214]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by province.act-europe.fr (Postfix) with ESMTPSA id 4A414165B6C for ; Thu, 4 Dec 2008 16:28:26 +0100 (CET) Message-Id: From: Tristan Gingold To: gdb-patches@sourceware.org Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v929.2) Subject: [RFA] Darwin: single step through sigreturn Date: Thu, 04 Dec 2008 15:29:00 -0000 X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2008-12/txt/msg00066.txt.bz2 Hi, as other platform, single stepping through the sigreturn syscall is special: changing the cpu state is useless as the context is restored. The trace bit must be set in the to be restored context. Tristan. 2008-12-04 Tristan Gingold * i386-darwin-nat.c (i386_darwin_sstep_at_sigreturn): New function. (amd64_darwin_sstep_at_sigreturn): New function. (darwin_set_sstep): The sigreturn is a special case: the trace flag must be set in the mcontext structure. diff -c -p -r1.1 i386-darwin-nat.c *** i386-darwin-nat.c 27 Nov 2008 09:23:01 -0000 1.1 --- i386-darwin-nat.c 4 Dec 2008 15:27:37 -0000 *************** *** 34,39 **** --- 34,40 ---- #include "i387-tdep.h" #include "gdbarch.h" #include "arch-utils.h" + #include "gdbcore.h" #include "darwin-nat.h" #include "i386-darwin-tdep.h" *************** darwin_check_osabi (darwin_inferior *inf *** 433,438 **** --- 434,503 ---- #define X86_EFLAGS_T 0x100UL + /* Returning from a signal trampoline is done by calling a + special system call (sigreturn). This system call + restores the registers that were saved when the signal was + raised, including %eflags/%rflags. That means that single-stepping + won't work. Instead, we'll have to modify the signal context + that's about to be restored, and set the trace flag there. */ + + static int + i386_darwin_sstep_at_sigreturn (x86_thread_state_t *regs) + { + static const gdb_byte darwin_syscall[] = { 0xcd, 0x80 }; /* int 0x80 */ + gdb_byte buf[sizeof (darwin_syscall)]; + + /* Check if PC is at a sigreturn system call. */ + if (target_read_memory (regs->uts.ts32.__eip, buf, sizeof (buf)) == 0 + && memcmp (buf, darwin_syscall, sizeof (darwin_syscall)) == 0 + && regs->uts.ts32.__eax == 0xb8 /* SYS_sigreturn */) + { + ULONGEST uctx_addr; + ULONGEST mctx_addr; + ULONGEST flags_addr; + unsigned int eflags; + + uctx_addr = read_memory_unsigned_integer (regs->uts.ts32.__esp + 4, 4); + mctx_addr = read_memory_unsigned_integer (uctx_addr + 28, 4); + + flags_addr = mctx_addr + 12 + 9 * 4; + read_memory (flags_addr, (gdb_byte *) &eflags, 4); + eflags |= X86_EFLAGS_T; + write_memory (flags_addr, (gdb_byte *) &eflags, 4); + + return 1; + } + return 0; + } + + static int + amd64_darwin_sstep_at_sigreturn (x86_thread_state_t *regs) + { + static const gdb_byte darwin_syscall[] = { 0x0f, 0x05 }; /* syscall */ + gdb_byte buf[sizeof (darwin_syscall)]; + + /* Check if PC is at a sigreturn system call. */ + if (target_read_memory (regs->uts.ts64.__rip, buf, sizeof (buf)) == 0 + && memcmp (buf, darwin_syscall, sizeof (darwin_syscall)) == 0 + && (regs->uts.ts64.__rax & 0xffffffff) == 0x20000b8 /* SYS_sigreturn */) + { + ULONGEST mctx_addr; + ULONGEST flags_addr; + unsigned int rflags; + + mctx_addr = read_memory_unsigned_integer (regs->uts.ts64.__rdi + 48, 8); + flags_addr = mctx_addr + 16 + 17 * 8; + + /* AMD64 is little endian. */ + read_memory (flags_addr, (gdb_byte *) &rflags, 4); + rflags |= X86_EFLAGS_T; + write_memory (flags_addr, (gdb_byte *) &rflags, 4); + + return 1; + } + return 0; + } + void darwin_set_sstep (thread_t thread, int enable) { *************** darwin_set_sstep (thread_t thread, int e *** 448,459 **** --- 513,527 ---- kret, thread); return; } + switch (regs.tsh.flavor) { case x86_THREAD_STATE32: { __uint32_t bit = enable ? X86_EFLAGS_T : 0; + if (enable && i386_darwin_sstep_at_sigreturn (®s)) + return; if ((regs.uts.ts32.__eflags & X86_EFLAGS_T) == bit) return; regs.uts.ts32.__eflags = (regs.uts.ts32.__eflags & ~X86_EFLAGS_T) | bit; *************** darwin_set_sstep (thread_t thread, int e *** 466,471 **** --- 534,541 ---- { __uint64_t bit = enable ? X86_EFLAGS_T : 0; + if (enable && amd64_darwin_sstep_at_sigreturn (®s)) + return; if ((regs.uts.ts64.__rflags & X86_EFLAGS_T) == bit) return; regs.uts.ts64.__rflags = (regs.uts.ts64.__rflags & ~X86_EFLAGS_T) | bit;