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56bd759df1
This commit represents a new era for Gentoo: Storing the gentoo-x86 tree in Git, as converted from CVS. This commit is the start of the NEW history. Any historical data is intended to be grafted onto this point. Creation process: 1. Take final CVS checkout snapshot 2. Remove ALL ChangeLog* files 3. Transform all Manifests to thin 4. Remove empty Manifests 5. Convert all stale $Header$/$Id$ CVS keywords to non-expanded Git $Id$ 5.1. Do not touch files with -kb/-ko keyword flags. Signed-off-by: Robin H. Johnson <robbat2@gentoo.org> X-Thanks: Alec Warner <antarus@gentoo.org> - did the GSoC 2006 migration tests X-Thanks: Robin H. Johnson <robbat2@gentoo.org> - infra guy, herding this project X-Thanks: Nguyen Thai Ngoc Duy <pclouds@gentoo.org> - Former Gentoo developer, wrote Git features for the migration X-Thanks: Brian Harring <ferringb@gentoo.org> - wrote much python to improve cvs2svn X-Thanks: Rich Freeman <rich0@gentoo.org> - validation scripts X-Thanks: Patrick Lauer <patrick@gentoo.org> - Gentoo dev, running new 2014 work in migration X-Thanks: Michał Górny <mgorny@gentoo.org> - scripts, QA, nagging X-Thanks: All of other Gentoo developers - many ideas and lots of paint on the bikeshed
80 lines
2.5 KiB
Diff
80 lines
2.5 KiB
Diff
# HG changeset patch
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# User Armin Rigo <arigo@tunes.org>
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# Date 1424942568 -3600
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# Node ID c7edb1e84eb3c29cac0674790cb4efcbcf1683b2
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# Parent 95e0563201602a2e1a8d83cc95a6a70048dfeece
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issue #177: workaround for some Linux kernels
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diff --git a/c/malloc_closure.h b/c/malloc_closure.h
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--- a/c/malloc_closure.h
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+++ b/c/malloc_closure.h
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@@ -14,6 +14,54 @@
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# endif
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#endif
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+/* On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC.
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+
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+ This is, apparently, an undocumented change to ffi_prep_closure():
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+ depending on the Linux kernel we're running on, we must give it a
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+ mmap that is either PROT_READ|PROT_WRITE|PROT_EXEC or only
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+ PROT_READ|PROT_WRITE. In the latter case, just trying to obtain a
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+ mmap with PROT_READ|PROT_WRITE|PROT_EXEC would kill our process(!),
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+ but in that situation libffi is fine with only PROT_READ|PROT_WRITE.
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+ There is nothing in the libffi API to know that, though, so we have
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+ to guess by parsing /proc/self/status. "Meh."
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+ */
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+#ifdef __linux__
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+#include <stdlib.h>
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+
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+static int emutramp_enabled = -1;
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+
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+static int
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+emutramp_enabled_check (void)
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+{
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+ char *buf = NULL;
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+ size_t len = 0;
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+ FILE *f;
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+ int ret;
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+ f = fopen ("/proc/self/status", "r");
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+ if (f == NULL)
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+ return 0;
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+ ret = 0;
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+
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+ while (getline (&buf, &len, f) != -1)
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+ if (!strncmp (buf, "PaX:", 4))
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+ {
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+ char emutramp;
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+ if (sscanf (buf, "%*s %*c%c", &emutramp) == 1)
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+ ret = (emutramp == 'E');
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+ break;
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+ }
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+ free (buf);
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+ fclose (f);
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+ return ret;
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+}
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+
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+#define is_emutramp_enabled() (emutramp_enabled >= 0 ? emutramp_enabled \
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+ : (emutramp_enabled = emutramp_enabled_check ()))
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+#else
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+#define is_emutramp_enabled() 0
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+#endif
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+
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+
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/* 'allocate_num_pages' is dynamically adjusted starting from one
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page. It grows by a factor of PAGE_ALLOCATION_GROWTH_RATE. This is
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meant to handle both the common case of not needing a lot of pages,
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@@ -77,9 +125,12 @@
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if (item == NULL)
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return;
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#else
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+ int prot = PROT_READ | PROT_WRITE | PROT_EXEC;
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+ if (is_emutramp_enabled ())
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+ prot &= ~PROT_EXEC;
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item = (union mmaped_block *)mmap(NULL,
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allocate_num_pages * _pagesize,
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- PROT_READ | PROT_WRITE | PROT_EXEC,
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+ prot,
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MAP_PRIVATE | MAP_ANONYMOUS,
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-1,
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0);
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