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From: Adriaan van Os
Subject: Building latest gpc on Intel OS X 10.5.2
Date: 15 Mar 2008, 11:46:35
Gale Paeper wrote:
>> Actually I had installed the patch Gale mentioned and actually there
>> is a problem. For some reason under 10.5.2 the symbol __sysctl is not
>> found but sysctl works. I therefore replaced __sysctl by sysctl in the
>> patch and the build now proceeds to a new kind of problem:
>
> That one I think is new with 10.5.2. Since Adriaan's supplied
> trampoline patch doesn't use __sysctl, I'm curious as to where the
> symbol __sysctl occurrence is located.
Yes, there may be a mix-up. The old trampoline patch *did* use __sysctl
# Waldek Hebisch <hebisch@math.uni.wroc.pl> & Adriaan van Os <gpc@microbizz.nl>
# Fix trampolines on i386-apple-darwin, by making the stack executable (see
# <http://www.gnu-pascal.de/crystal/gpc/en/mail12945.html> and
# <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24959>)
diff -urN gcc-3.4.5-orig/gcc/config/i386/darwin.h gcc-3.4.5/gcc/config/i386/darwin.h
--- gcc-3.4.5-orig/gcc/config/i386/darwin.h 2005-12-15 17:41:52.000000000 +0100
+++ gcc-3.4.5/gcc/config/i386/darwin.h 2005-12-17 15:31:03.000000000 +0100
@@ -137,3 +140,50 @@
} \
else fprintf (FILE, "\tcall mcount\n"); \
} while (0)
+
+
+/* Attempt to turn on execute permission for the stack. This may be
+ used by INITIALIZE_TRAMPOLINE of the target needs it (that is,
+ if the target machine can change execute permissions on a page).
+
+ There is no way to query the execute permission of the stack, so
+ we always issue the mprotect() call.
+
+ Note that we go out of our way to use namespace-non-invasive calls
+ here. Unfortunately, there is no libc-internal name for mprotect().
+
+ Also note that no errors should be emitted by this code; it is considered
+ dangerous for library calls to send messages to stdout/stderr. */
+
+#define ENABLE_EXECUTE_STACK \
+extern void __enable_execute_stack (void *); \
+void \
+__enable_execute_stack (void *addr) \
+{ \
+ extern int mprotect (void *, size_t, int); \
+ extern int __sysctl (int *, unsigned int, void *, size_t *, \
+ void *, size_t); \
+ \
+ static int size; \
+ static long mask; \
+ \
+ char *page, *end; \
+ \
+ if (size == 0) \
+ { \
+ int mib[2]; \
+ size_t len; \
+ \
+ mib[0] = 6; /* CTL_HW */ \
+ mib[1] = 7; /* HW_PAGESIZE */ \
+ len = sizeof (size); \
+ (void) __sysctl (mib, 2, &size, &len, NULL, 0); \
+ mask = ~((long) size - 1); \
+ } \
+ \
+ page = (char *) (((long) addr) & mask); \
+ end = (char *) ((((long) (addr + TRAMPOLINE_SIZE)) & mask) + size); \
+ \
+ /* 7 == PROT_READ | PROT_WRITE | PROT_EXEC */ \
+ (void) mprotect (page, end - page, 7); \
+}
but it was changed for Mac OS X 10.5 *not* to use __sysctl, as follows
# Waldek Hebisch <hebisch@math.uni.wroc.pl> & Adriaan van Os <gpc@microbizz.nl>
# Fix trampolines on i386-apple-darwin, by making the stack executable (see
# <http://www.gnu-pascal.de/crystal/gpc/en/mail12945.html> and
# <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24959>)
# later modified by Geoffrey Keating
# 2006-09-27 Geoffrey Keating <geoffk@apple.com>
# avoid use of __sysctl on Darwin
# see <http://gcc.gnu.org/ml/gcc-patches/2006-09/msg01277.html>
# 20070922, and then backported to gcc-3.4.5 by Adriaan van Os <gpc@microbizz.nl>
diff -ur gcc-3.4.5-orig/gcc/config/i386/darwin.h gcc-3.4.5/gcc/config/i386/darwin.h
--- gcc-3.4.5-orig/gcc/config/i386/darwin.h 2004-08-23 20:03:13.000000000 +0200
+++ gcc-3.4.5/gcc/config/i386/darwin.h 2007-09-23 13:22:24.000000000 +0200
@@ -137,3 +140,42 @@
} \
else fprintf (FILE, "\tcall mcount\n"); \
} while (0)
+
+
+/* Attempt to turn on execute permission for the stack. This may be
+ used by INITIALIZE_TRAMPOLINE of the target needs it (that is,
+ if the target machine can change execute permissions on a page).
+
+ There is no way to query the execute permission of the stack, so
+ we always issue the mprotect() call.
+
+ Unfortunately it is not possible to make this namespace-clean.
+
+ Also note that no errors should be emitted by this code; it is
+ considered dangerous for library calls to send messages to
+ stdout/stderr. */
+
+#define ENABLE_EXECUTE_STACK \
+extern void __enable_execute_stack (void *); \
+void \
+__enable_execute_stack (void *addr) \
+{ \
+ extern int mprotect (void *, size_t, int); \
+ extern int getpagesize (void); \
+ static int size; \
+ static long mask; \
+ \
+ char *page, *end; \
+ \
+ if (size == 0) \
+ { \
+ size = getpagesize(); \
+ mask = ~((long) size - 1); \
+ } \
+ \
+ page = (char *) (((long) addr) & mask); \
+ end = (char *) ((((long) (addr + (TARGET_64BIT ? 48 : 40))) & mask) + size); \
+ \
+ /* 7 == PROT_READ | PROT_WRITE | PROT_EXEC */ \
+ (void) mprotect (page, end - page, 7); \
+}
Regards,
Adriaan van Os
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