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Diffstat (limited to 'translate/grt/config/linux.c')
| -rw-r--r-- | translate/grt/config/linux.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/translate/grt/config/linux.c b/translate/grt/config/linux.c new file mode 100644 index 000000000..047cfd1b4 --- /dev/null +++ b/translate/grt/config/linux.c @@ -0,0 +1,268 @@ +/* GRT stacks implementation for linux and other *nix. + Copyright (C) 2002, 2003, 2004, 2005 Tristan Gingold. + + GHDL 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 2, or (at your option) any later + version. + + GHDL 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 GCC; see the file COPYING. If not, write to the Free + Software Foundation, 59 Temple Place - Suite 330, Boston, MA + 02111-1307, USA. +*/ +#define _GNU_SOURCE +#include <unistd.h> +#include <sys/mman.h> +#include <signal.h> +#include <fcntl.h> +#include <sys/ucontext.h> +//#include <stdint.h> + +/* On x86, the stack growns downward. */ +#define STACK_GROWNS_DOWNWARD 1 + +#ifdef linux +/* If set, SIGSEGV is caught in order to automatically grow the stacks. */ +#define EXTEND_STACK 1 +#endif + +/* Defined in Grt.Stacks. */ +extern unsigned int stack_size; +extern unsigned int stack_max_size; + +/* Size of a memory page. */ +static size_t page_size; + +extern void grt_stack_error_grow_failed (void); +extern void grt_stack_error_null_access (void); +extern void grt_stack_error_memory_access (void); +extern void grt_overflow_error (void); + +/* Definitions: + The base of the stack is the address before the first available byte on the + stack. If the stack grows downward, the base is equal to the high bound. +*/ + +/* Per stack context. + This context is allocated at the top (or bottom if the stack grows + upward) of the stack. + Therefore, the base of the stack can be easily deduced from the context. */ +struct stack_context +{ + /* The current stack pointer. */ + void *cur_sp; + /* The current stack length. */ + size_t cur_length; +}; + +/* Context for the main stack. */ +static struct stack_context main_stack_context; + +extern struct stack_context *grt_stack_main_stack; + +/* If MAP_ANONYMOUS is not defined, use /dev/zero. */ +#ifndef MAP_ANONYMOUS +#define USE_DEV_ZERO +static int dev_zero_fd; +#define MAP_ANONYMOUS 0 +#define MMAP_FILEDES dev_zero_fd +#else +#define MMAP_FILEDES -1 +#endif + +#if EXTEND_STACK +/* Defined in Grt.Processes (body). + This is the current process being run. + FIXME: this won't work with pthread! */ +extern void **grt_cur_proc; + +/* Stack used for signals. + The stack must be different from the running stack, because we want to be + able to extend the running stack. When the stack need to be extended, the + current stack pointer does not point to a valid address. Therefore, the + stack cannot be used or else a second SIGSEGV is generated while the + arguments are pushed. */ +static unsigned long sig_stack[SIGSTKSZ / sizeof (long)]; + +/* Signal stack descriptor. */ +static stack_t sig_stk; + +static struct sigaction prev_sigsegv_act; +static struct sigaction sigsegv_act; + +/* The following code assumes stack grows downward. */ +#if !STACK_GROWNS_DOWNWARD +#error "Not implemented" +#endif + +/* Handler for SIGSEGV signal, which grow the stack. */ +static void grt_sigsegv_handler (int signo, siginfo_t *info, void *ptr) +{ + static int in_handler; + void *addr; + struct stack_context *ctxt; + void *stack_high; + void *stack_low; + void *n_low; + size_t n_len; + ucontext_t *uctxt = (ucontext_t *)ptr; + + in_handler++; + +#ifdef __i386__ + /* Linux generates a SIGSEGV (!) for an overflow exception. */ + if (uctxt->uc_mcontext.gregs[REG_TRAPNO] == 4) + { + grt_overflow_error (); + } +#endif + + if (info == NULL || grt_cur_proc == NULL || in_handler > 1) + { + /* We loose. */ + sigaction (SIGSEGV, &prev_sigsegv_act, NULL); + return; + } + + addr = info->si_addr; + + /* Check ADDR belong to the stack. */ + ctxt = *grt_cur_proc; + stack_high = (void *)(ctxt + 1); + stack_low = stack_high - stack_max_size; + if (addr > stack_high || addr < stack_low) + { + /* Out of the stack. */ + if (addr < (void *)page_size) + grt_stack_error_null_access (); + else + grt_stack_error_memory_access (); + } + /* Compute the address of the faulting page. */ + n_low = (void *)((unsigned long)addr & ~(page_size - 1)); + + /* Should not happen. */ + if (n_low < stack_low) + abort (); + + /* Allocate one more page, if possible. */ + if (n_low != stack_low) + n_low -= page_size; + + /* Compute the new length. */ + n_len = stack_high - n_low; + + if (mmap (n_low, n_len - ctxt->cur_length, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, MMAP_FILEDES, 0) + != n_low) + { + /* Cannot grow the stack. */ + grt_stack_error_grow_failed (); + } + + ctxt->cur_length = n_len; + + sigaction (SIGSEGV, &sigsegv_act, NULL); + + in_handler--; + + /* Hopes we can resume! */ + return; +} + +static void grt_signal_setup (void) +{ + sigsegv_act.sa_sigaction = &grt_sigsegv_handler; + sigemptyset (&sigsegv_act.sa_mask); + sigsegv_act.sa_flags = SA_ONESHOT | SA_ONSTACK | SA_SIGINFO; + + /* Use an alternate stack during signals. */ + sig_stk.ss_sp = sig_stack; + sig_stk.ss_size = sizeof (sig_stack); + sig_stk.ss_flags = 0; + sigaltstack (&sig_stk, NULL); + + /* We don't care about the return status. + If the handler is not installed, then some feature are lost. */ + sigaction (SIGSEGV, &sigsegv_act, &prev_sigsegv_act); +} +#endif + +void +grt_stack_init (void) +{ + size_t pg_round; + + page_size = getpagesize (); + pg_round = page_size - 1; + + /* Align size. */ + stack_size = (stack_size + pg_round) & ~pg_round; + stack_max_size = (stack_max_size + pg_round) & ~pg_round; + + /* Set mimum values. */ + if (stack_size < 2 * page_size) + stack_size = 2 * page_size; + if (stack_max_size < (stack_size + 2 * page_size)) + stack_max_size = stack_size + 2 * page_size; + + /* Initialize the main stack context. */ + main_stack_context.cur_sp = NULL; + main_stack_context.cur_length = 0; + grt_stack_main_stack = &main_stack_context; + +#ifdef USE_DEV_ZERO + dev_zero_fd = open ("/dev/zero", O_RDWR); + if (dev_zero_fd < 0) + abort (); +#endif + +#if EXTEND_STACK + grt_signal_setup (); +#endif +} + +/* Allocate a stack. + Called by i386.S */ +struct stack_context * +grt_stack_allocate (void) +{ + struct stack_context *res; + void *r; + void *base; + + /* Allocate the stack, but without any rights. This is a guard. */ + base = (void *)mmap (NULL, stack_max_size, PROT_NONE, + MAP_PRIVATE | MAP_ANONYMOUS, MMAP_FILEDES, 0); + + if (base == (void *)-1) + return NULL; + + /* Set rights on the allocated stack. */ +#if STACK_GROWNS_DOWNWARD + r = base + stack_max_size - stack_size; +#else + r = base; +#endif + if (mmap (r, stack_size, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, MMAP_FILEDES, 0) + != r) + return NULL; + +#if STACK_GROWNS_DOWNWARD + res = (struct stack_context *) + (base + stack_max_size - sizeof (struct stack_context)); +#else + res = (struct stack_context *)(base + sizeof (struct stack_context)); +#endif + + res->cur_sp = (void *)res; + res->cur_length = stack_size; + return res; +} |