| /**************************************************************************** |
| * * |
| * GNAT COMPILER COMPONENTS * |
| * * |
| * S I G T R A M P * |
| * * |
| * Asm Implementation File * |
| * * |
| * Copyright (C) 2015-2019, Free Software Foundation, Inc. * |
| * * |
| * GNAT is free software; you can redistribute it and/or modify it under * |
| * terms of the GNU General Public License as published by the Free Soft- * |
| * ware Foundation; either version 3, or (at your option) any later ver- * |
| * sion. GNAT is distributed in the hope that it will be useful, but WITH- * |
| * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * |
| * or FITNESS FOR A PARTICULAR PURPOSE. * |
| * * |
| * As a special exception under Section 7 of GPL version 3, you are granted * |
| * additional permissions described in the GCC Runtime Library Exception, * |
| * version 3.1, as published by the Free Software Foundation. * |
| * * |
| * In particular, you can freely distribute your programs built with the * |
| * GNAT Pro compiler, including any required library run-time units, using * |
| * any licensing terms of your choosing. See the AdaCore Software License * |
| * for full details. * |
| * * |
| * GNAT was originally developed by the GNAT team at New York University. * |
| * Extensive contributions were provided by Ada Core Technologies Inc. * |
| * * |
| ****************************************************************************/ |
| |
| /****************************************************** |
| * ARM-Android version of the __gnat_sigtramp service * |
| ******************************************************/ |
| |
| #include <sys/ucontext.h> |
| |
| #include "sigtramp.h" |
| /* See sigtramp.h for a general explanation of functionality. */ |
| |
| /* ---------------------- |
| -- General comments -- |
| ---------------------- |
| |
| Stubs are generated from toplevel asms, |
| The general idea is to establish CFA as the sigcontext |
| and state where to find the registers as offsets from there. |
| |
| We support stubs for VxWorks and Android, providing unwind info for |
| common registers. We might need variants with support for floating |
| point or altivec registers as well at some point. |
| |
| For Android it would be simpler to write this in Asm since there's only |
| one variant, but to keep it looking like the VxWorks stubs, |
| C is the choice for our toplevel interface. |
| |
| Note that the registers we "restore" here are those to which we have |
| direct access through the system sigcontext structure, which includes |
| only a partial set of the non-volatiles ABI-wise. */ |
| |
| /* ----------------------------------------- |
| -- Protypes for our internal asm stubs -- |
| ----------------------------------------- |
| |
| The registers are expected to be at SIGCONTEXT + 12 (reference the |
| sicontext structure in asm/sigcontext.h which describes the first |
| 3 * 4byte fields.) Even though our symbols will remain local, the |
| prototype claims "extern" and not "static" to prevent compiler complaints |
| about a symbol used but never defined. */ |
| |
| /* sigtramp stub providing unwind info for common registers. */ |
| |
| extern void __gnat_sigtramp_common |
| (int signo, void *siginfo, void *sigcontext, |
| __sigtramphandler_t * handler); |
| |
| void __gnat_sigtramp (int signo, void *si, void *sc, |
| __sigtramphandler_t * handler) |
| __attribute__((optimize(2))); |
| |
| void __gnat_sigtramp (int signo, void *si, void *ucontext, |
| __sigtramphandler_t * handler) |
| { |
| struct sigcontext *mcontext = &((ucontext_t *) ucontext)->uc_mcontext; |
| |
| __gnat_sigtramp_common (signo, si, mcontext, handler); |
| } |
| |
| /* asm string construction helpers. */ |
| |
| #define STR(TEXT) #TEXT |
| /* stringify expanded TEXT, surrounding it with double quotes. */ |
| |
| #define S(E) STR(E) |
| /* stringify E, which will resolve as text but may contain macros |
| still to be expanded. */ |
| |
| /* asm (TEXT) outputs <tab>TEXT. These facilitate the output of |
| multiline contents: */ |
| #define TAB(S) "\t" S |
| #define CR(S) S "\n" |
| |
| #undef TCR |
| #define TCR(S) TAB(CR(S)) |
| |
| /* Trampoline body block |
| --------------------- */ |
| |
| #define SIGTRAMP_BODY \ |
| CR("") \ |
| TCR("# Allocate frame and also save r2 which is the argument register") \ |
| TCR("# containing the sigcontext, so that we can restore it during") \ |
| TCR("# unwinding and thereby load the rest of the desired context.") \ |
| TCR("stmfd sp!, {r2, r3, lr}") \ |
| TCR("# The unwinder undo's these operations in reverse order so starting") \ |
| TCR("# from bottom, restore r2 from the current vsp location, move r2 into") \ |
| TCR("# the vsp, add 12 bytes to get the start of the register save area") \ |
| TCR("# then restore the 15 general purpose registers of the frame which") \ |
| TCR("# raised the signal.") \ |
| TCR(".save {r0-r15}") \ |
| TCR(".pad #12") \ |
| TCR(".movsp r2") \ |
| TCR(".save {r2}") \ |
| TCR("# Call the real handler. The signo, siginfo and sigcontext") \ |
| TCR("# arguments are the same as those we received in r0, r1 and r2.") \ |
| TCR("blx r3") \ |
| TCR("# Restore our callee-saved items, release our frame and return") \ |
| TCR("# (should never get here!).") \ |
| TCR("ldmfd sp, {r2, r3, pc}") |
| |
| /* Symbol definition block |
| ----------------------- */ |
| |
| #define SIGTRAMP_START(SYM) \ |
| CR("# " S(SYM) " unwind trampoline") \ |
| TCR(".type " S(SYM) ", %function") \ |
| CR("") \ |
| CR(S(SYM) ":") \ |
| TCR(".fnstart") |
| |
| /* Symbol termination block |
| ------------------------ */ |
| |
| #define SIGTRAMP_END(SYM) \ |
| CR(".fnend") \ |
| TCR(".size " S(SYM) ", .-" S(SYM)) |
| |
| /*---------------------------- |
| -- And now, the real code -- |
| ---------------------------- */ |
| |
| /* Text section start. The compiler isn't aware of that switch. */ |
| |
| asm (".text\n" |
| TCR(".align 2")); |
| |
| /* sigtramp stub for common registers. */ |
| |
| #define TRAMP_COMMON __gnat_sigtramp_common |
| |
| asm (SIGTRAMP_START(TRAMP_COMMON)); |
| asm (SIGTRAMP_BODY); |
| asm (SIGTRAMP_END(TRAMP_COMMON)); |