PING: V3 [PATCH] x86: Remove ARCH_CET_LEGACY_BITMAP [BZ #25397]
Carlos O'Donell
carlos@redhat.com
Mon Mar 16 23:41:54 GMT 2020
On 3/13/20 9:25 AM, H.J. Lu via Libc-alpha wrote:
> On Tue, Mar 10, 2020 at 06:36:54AM -0700, H.J. Lu wrote:
>> On Tue, Mar 10, 2020 at 02:13:37PM +0100, Florian Weimer wrote:
>>> * H. J. Lu:
>>>
>>>>> I think the error message should say *where* indirect branch tracking
>>>>> is not enabled. I assume this is a property of the loaded object.
>>>> Fixed. Now I got
>>>>
>>>> .... libvirtd[1048]: internal error: Failed to load module
>>>> '/usr/lib64/libvirt/storage-backend/libvirt_storage_backend_rbd.so':
>>>> /usr/lib64/ceph/libceph-common.so.0: indirect branch tracking isn't
>>>> enabled: Invalid argument
>>> What I meant is that the error message should say that the object
>>> needs to be rebuilt with IBT/SHSTK support. In the above, it's
>>> unclear whether the process or the object has to enable IBT.
>>>
>>> (The Invalid Argument part should also be suppressed.)
>> Like this? The diff against V2 patch is:
>>
>> diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
>> index f527a1414c..b2843488be 100644
>> --- a/sysdeps/x86/dl-cet.c
>> +++ b/sysdeps/x86/dl-cet.c
>> @@ -142,10 +142,10 @@ dl_cet_check (struct link_map *m, const char *program)
>> /* When IBT is enabled, we cannot dlopen a shared
>> object without IBT. */
>> if (found_ibt_legacy)
>> - _dl_signal_error (EINVAL,
>> + _dl_signal_error (0,
>> m->l_initfini[ibt_legacy]->l_name,
>> "dlopen",
>> - N_("indirect branch tracking isn't enabled"));
>> + N_("rebuilt with IBT support needed"));
>> }
>>
>> if (enable_shstk_type != CET_PERMISSIVE)
>> @@ -153,10 +153,10 @@ dl_cet_check (struct link_map *m, const char *program)
>> /* When SHSTK is enabled, we cannot dlopen a shared
>> object without SHSTK. */
>> if (found_shstk_legacy)
>> - _dl_signal_error (EINVAL,
>> + _dl_signal_error (0,
>> m->l_initfini[shstk_legacy]->l_name,
>> "dlopen",
>> - N_("shadow stack isn't enabled"));
>> + N_("rebuilt with SHSTK support needed"));
>> }
>>
>> if (enable_ibt_type != CET_PERMISSIVE
>>
> PING.
Please post v4 with adjusted error message, and expanded comment in new test,
and I'll review that quickly.
> H.J.
> ---
> Since legacy bitmap doesn't cover jitted code generated by legacy JIT
> engine, it isn't very useful. This patch removes ARCH_CET_LEGACY_BITMAP
> and treats indirect branch tracking similar to shadow stack by removing
> legacy bitmap support.
OK.
>
> * sysdeps/unix/sysv/linux/x86/dl-cet.h
> (dl_cet_allocate_legacy_bitmap): Removed.
> * sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> (ARCH_CET_LEGACY_BITMAP): Removed.
> * sysdeps/x86/Makefile (tests): Add tst-cet-legacy-7.
> (CFLAGS-tst-cet-legacy-mod-5a.c): Changed to
> -fcf-protection=branch.
> (CFLAGS-tst-cet-legacy-mod-6a.c): Likewise.
> (CFLAGS-tst-cet-legacy-7.c): New.
> * sysdeps/x86/dl-cet.c (dl_cet_mark_legacy_region): Removed.
> (dl_cet_check): Remove legacy bitmap support. Don't allow
> dlopening legacy shared library when IBT is enabled. Set
> feature_1 if IBT or SHSTK is enabled in executable.
> * sysdeps/x86/dl-procruntime.c (_dl_x86_legacy_bitmap): Removed.
> * sysdeps/x86/tst-cet-legacy-4.c: Include <string.h> and
> <support/check.h>.
> (do_test): Check indirect branch tracking error. Use
> FAIL_EXIT1.
> * sysdeps/x86/tst-cet-legacy-7.c: New file.
Hopefully you don't plan to include this in the commit log :-)
> ---
> sysdeps/unix/sysv/linux/x86/dl-cet.h | 20 --
> .../unix/sysv/linux/x86/include/asm/prctl.h | 5 -
> sysdeps/x86/Makefile | 7 +-
> sysdeps/x86/dl-cet.c | 217 +++++-------------
> sysdeps/x86/dl-procruntime.c | 11 -
> sysdeps/x86/tst-cet-legacy-4.c | 19 +-
> sysdeps/x86/tst-cet-legacy-5.c | 2 +-
> sysdeps/x86/tst-cet-legacy-6.c | 2 +-
> sysdeps/x86/tst-cet-legacy-7.c | 36 +++
> 9 files changed, 111 insertions(+), 208 deletions(-)
> create mode 100644 sysdeps/x86/tst-cet-legacy-7.c
>
> diff --git a/sysdeps/unix/sysv/linux/x86/dl-cet.h b/sysdeps/unix/sysv/linux/x86/dl-cet.h
> index 9b2aaa238c..ae97a433a2 100644
> --- a/sysdeps/unix/sysv/linux/x86/dl-cet.h
> +++ b/sysdeps/unix/sysv/linux/x86/dl-cet.h
> @@ -18,26 +18,6 @@
> #include <sys/prctl.h>
> #include <asm/prctl.h>
>
> -static inline int __attribute__ ((always_inline))
> -dl_cet_allocate_legacy_bitmap (unsigned long *legacy_bitmap)
> -{
> - /* Allocate legacy bitmap. */
> -#ifdef __LP64__
> - return (int) INTERNAL_SYSCALL_CALL (arch_prctl,
> - ARCH_CET_LEGACY_BITMAP, legacy_bitmap);
> -#else
> - unsigned long long legacy_bitmap_u64[2];
> - int res = INTERNAL_SYSCALL_CALL (arch_prctl,
> - ARCH_CET_LEGACY_BITMAP, legacy_bitmap_u64);
> - if (res == 0)
> - {
> - legacy_bitmap[0] = legacy_bitmap_u64[0];
> - legacy_bitmap[1] = legacy_bitmap_u64[1];
> - }
> - return res;
> -#endif
> -}
> -
OK.
> static inline int __attribute__ ((always_inline))
> dl_cet_disable_cet (unsigned int cet_feature)
> {
> diff --git a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> index f67f3299b9..45ad0b052f 100644
> --- a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> +++ b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> @@ -24,9 +24,4 @@
> OUT: allocated shadow stack address: *addr.
> */
> # define ARCH_CET_ALLOC_SHSTK 0x3004
> -/* Return legacy region bitmap info in unsigned long long *addr:
> - address: addr[0].
> - size: addr[1].
> - */
> -# define ARCH_CET_LEGACY_BITMAP 0x3005
OK.
> #endif /* ARCH_CET_STATUS */
> diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> index 95182a508c..ec96b59a78 100644
> --- a/sysdeps/x86/Makefile
> +++ b/sysdeps/x86/Makefile
> @@ -20,7 +20,7 @@ sysdep-dl-routines += dl-cet
>
> tests += tst-cet-legacy-1 tst-cet-legacy-1a tst-cet-legacy-2 \
> tst-cet-legacy-2a tst-cet-legacy-3 tst-cet-legacy-4 \
> - tst-cet-legacy-5a tst-cet-legacy-6a
> + tst-cet-legacy-5a tst-cet-legacy-6a tst-cet-legacy-7
OK.
> tst-cet-legacy-1a-ARGS = -- $(host-test-program-cmd)
> ifneq (no,$(have-tunables))
> tests += tst-cet-legacy-4a tst-cet-legacy-4b tst-cet-legacy-4c \
> @@ -43,14 +43,15 @@ CFLAGS-tst-cet-legacy-4b.c += -fcf-protection
> CFLAGS-tst-cet-legacy-mod-4.c += -fcf-protection=none
> CFLAGS-tst-cet-legacy-5a.c += -fcf-protection
> CFLAGS-tst-cet-legacy-5b.c += -fcf-protection
> -CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=none
> +CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=branch
> CFLAGS-tst-cet-legacy-mod-5b.c += -fcf-protection
> CFLAGS-tst-cet-legacy-mod-5c.c += -fcf-protection
> CFLAGS-tst-cet-legacy-6a.c += -fcf-protection
> CFLAGS-tst-cet-legacy-6b.c += -fcf-protection
> -CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=none
> +CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=branch
> CFLAGS-tst-cet-legacy-mod-6b.c += -fcf-protection
> CFLAGS-tst-cet-legacy-mod-6c.c += -fcf-protection
> +CFLAGS-tst-cet-legacy-7.c += -fcf-protection=none
OK.
>
> $(objpfx)tst-cet-legacy-1: $(objpfx)tst-cet-legacy-mod-1.so \
> $(objpfx)tst-cet-legacy-mod-2.so
> diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
> index ca3b5849bc..b2843488be 100644
> --- a/sysdeps/x86/dl-cet.c
> +++ b/sysdeps/x86/dl-cet.c
> @@ -33,63 +33,6 @@
> # error GNU_PROPERTY_X86_FEATURE_1_SHSTK != X86_FEATURE_1_SHSTK
> #endif
>
> -static int
> -dl_cet_mark_legacy_region (struct link_map *l)
> -{
> - /* Mark PT_LOAD segments with PF_X in legacy code page bitmap. */
> - size_t i, phnum = l->l_phnum;
> - const ElfW(Phdr) *phdr = l->l_phdr;
> -#ifdef __x86_64__
> - typedef unsigned long long word_t;
> -#else
> - typedef unsigned long word_t;
> -#endif
> - unsigned int bits_to_set;
> - word_t mask_to_set;
> -#define BITS_PER_WORD (sizeof (word_t) * 8)
> -#define BITMAP_FIRST_WORD_MASK(start) \
> - (~((word_t) 0) << ((start) & (BITS_PER_WORD - 1)))
> -#define BITMAP_LAST_WORD_MASK(nbits) \
> - (~((word_t) 0) >> (-(nbits) & (BITS_PER_WORD - 1)))
> -
> - word_t *bitmap = (word_t *) GL(dl_x86_legacy_bitmap)[0];
> - word_t bitmap_size = GL(dl_x86_legacy_bitmap)[1];
> - word_t *p;
> - size_t page_size = GLRO(dl_pagesize);
> -
> - for (i = 0; i < phnum; i++)
> - if (phdr[i].p_type == PT_LOAD && (phdr[i].p_flags & PF_X))
> - {
> - /* One bit in legacy bitmap represents a page. */
> - ElfW(Addr) start = (phdr[i].p_vaddr + l->l_addr) / page_size;
> - ElfW(Addr) len = (phdr[i].p_memsz + page_size - 1) / page_size;
> - ElfW(Addr) end = start + len;
> -
> - if ((end / 8) > bitmap_size)
> - return -EINVAL;
> -
> - p = bitmap + (start / BITS_PER_WORD);
> - bits_to_set = BITS_PER_WORD - (start % BITS_PER_WORD);
> - mask_to_set = BITMAP_FIRST_WORD_MASK (start);
> -
> - while (len >= bits_to_set)
> - {
> - *p |= mask_to_set;
> - len -= bits_to_set;
> - bits_to_set = BITS_PER_WORD;
> - mask_to_set = ~((word_t) 0);
> - p++;
> - }
> - if (len)
> - {
> - mask_to_set &= BITMAP_LAST_WORD_MASK (end);
> - *p |= mask_to_set;
> - }
> - }
> -
> - return 0;
> -}
> -
OK.
> /* Check if object M is compatible with CET. */
>
> static void
> @@ -117,6 +60,8 @@ dl_cet_check (struct link_map *m, const char *program)
> if (ibt_enabled || shstk_enabled)
> {
> struct link_map *l = NULL;
> + unsigned int ibt_legacy = 0, shstk_legacy = 0;
> + bool found_ibt_legacy = false, found_shstk_legacy = false;
OK.
>
> /* Check if IBT and SHSTK are enabled in object. */
> bool enable_ibt = (ibt_enabled
> @@ -142,10 +87,7 @@ dl_cet_check (struct link_map *m, const char *program)
> support IBT nor SHSTK. */
> if (enable_ibt || enable_shstk)
> {
> - int res;
> unsigned int i;
> - unsigned int first_legacy, last_legacy;
> - bool need_legacy_bitmap = false;
OK.
>
> i = m->l_searchlist.r_nlist;
> while (i-- > 0)
> @@ -167,91 +109,25 @@ dl_cet_check (struct link_map *m, const char *program)
> continue;
> #endif
>
> - if (enable_ibt
> - && enable_ibt_type != CET_ALWAYS_ON
> - && !(l->l_cet & lc_ibt))
> + /* IBT is enabled only if it is enabled in executable as
> + well as all shared objects. */
> + enable_ibt &= (enable_ibt_type == CET_ALWAYS_ON
> + || (l->l_cet & lc_ibt) != 0);
> + if (!found_ibt_legacy && enable_ibt != ibt_enabled)
> {
> - /* Remember the first and last legacy objects. */
> - if (!need_legacy_bitmap)
> - last_legacy = i;
> - first_legacy = i;
> - need_legacy_bitmap = true;
> + found_ibt_legacy = true;
> + ibt_legacy = i;
OK.
> }
>
> /* SHSTK is enabled only if it is enabled in executable as
> well as all shared objects. */
> enable_shstk &= (enable_shstk_type == CET_ALWAYS_ON
> || (l->l_cet & lc_shstk) != 0);
> - }
> -
> - if (need_legacy_bitmap)
> - {
> - if (GL(dl_x86_legacy_bitmap)[0])
> - {
> - /* Change legacy bitmap to writable. */
> - if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
> - GL(dl_x86_legacy_bitmap)[1],
> - PROT_READ | PROT_WRITE) < 0)
> - {
> -mprotect_failure:
> - if (program)
> - _dl_fatal_printf ("%s: mprotect legacy bitmap failed\n",
> - l->l_name);
> - else
> - _dl_signal_error (EINVAL, l->l_name, "dlopen",
> - N_("mprotect legacy bitmap failed"));
> - }
> - }
> - else
> + if (enable_shstk != shstk_enabled)
OK.
> {
> - /* Allocate legacy bitmap. */
> - int res = dl_cet_allocate_legacy_bitmap
> - (GL(dl_x86_legacy_bitmap));
> - if (res != 0)
> - {
> - if (program)
> - _dl_fatal_printf ("%s: legacy bitmap isn't available\n",
> - l->l_name);
> - else
> - _dl_signal_error (EINVAL, l->l_name, "dlopen",
> - N_("legacy bitmap isn't available"));
> - }
> + found_shstk_legacy = true;
> + shstk_legacy = i;
OK.
> }
> -
> - /* Put legacy shared objects in legacy bitmap. */
> - for (i = first_legacy; i <= last_legacy; i++)
> - {
> - l = m->l_initfini[i];
> -
> - if (l->l_init_called || (l->l_cet & lc_ibt))
> - continue;
> -
> -#ifdef SHARED
> - if (l == &GL(dl_rtld_map)
> - || l->l_real == &GL(dl_rtld_map)
> - || (program && l == m))
> - continue;
> -#endif
> -
> - /* If IBT is enabled in executable and IBT isn't enabled
> - in this shard object, mark PT_LOAD segments with PF_X
> - in legacy code page bitmap. */
> - res = dl_cet_mark_legacy_region (l);
> - if (res != 0)
> - {
> - if (program)
> - _dl_fatal_printf ("%s: failed to mark legacy code region\n",
> - l->l_name);
> - else
> - _dl_signal_error (-res, l->l_name, "dlopen",
> - N_("failed to mark legacy code region"));
> - }
> - }
> -
> - /* Change legacy bitmap to read-only. */
> - if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
> - GL(dl_x86_legacy_bitmap)[1], PROT_READ) < 0)
> - goto mprotect_failure;
OK.
> }
> }
>
> @@ -259,23 +135,40 @@ mprotect_failure:
>
> if (enable_ibt != ibt_enabled || enable_shstk != shstk_enabled)
> {
> - if (!program
> - && enable_shstk_type != CET_PERMISSIVE)
> + if (!program)
> {
> - /* When SHSTK is enabled, we can't dlopening a shared
> - object without SHSTK. */
> - if (enable_shstk != shstk_enabled)
> - _dl_signal_error (EINVAL, l->l_name, "dlopen",
> - N_("shadow stack isn't enabled"));
> - return;
> + if (enable_ibt_type != CET_PERMISSIVE)
> + {
> + /* When IBT is enabled, we cannot dlopen a shared
> + object without IBT. */
> + if (found_ibt_legacy)
> + _dl_signal_error (0,
> + m->l_initfini[ibt_legacy]->l_name,
> + "dlopen",
> + N_("rebuilt with IBT support needed"));
> + }
Suggest:
"rebuild shared object with IBT support enabled"
> +
> + if (enable_shstk_type != CET_PERMISSIVE)
> + {
> + /* When SHSTK is enabled, we cannot dlopen a shared
> + object without SHSTK. */
> + if (found_shstk_legacy)
> + _dl_signal_error (0,
> + m->l_initfini[shstk_legacy]->l_name,
> + "dlopen",
> + N_("rebuilt with SHSTK support needed"));
> + }
Suggest:
"rebuild shared object with SHSTK support enabled"
> +
> + if (enable_ibt_type != CET_PERMISSIVE
> + && enable_shstk_type != CET_PERMISSIVE)
> + return;
> }
>
> /* Disable IBT and/or SHSTK if they are enabled by kernel, but
> disabled in executable or shared objects. */
> unsigned int cet_feature = 0;
>
> - /* Disable IBT only during program startup. */
> - if (program && !enable_ibt)
> + if (!enable_ibt)
OK.
> cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
> if (!enable_shstk)
> cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
> @@ -286,8 +179,14 @@ mprotect_failure:
> if (program)
> _dl_fatal_printf ("%s: can't disable CET\n", program);
> else
> - _dl_signal_error (-res, l->l_name, "dlopen",
> - N_("can't disable CET"));
> + {
> + if (found_ibt_legacy)
> + l = m->l_initfini[ibt_legacy];
> + else
> + l = m->l_initfini[shstk_legacy];
> + _dl_signal_error (-res, l->l_name, "dlopen",
> + N_("can't disable CET"));
OK.
> + }
> }
>
> /* Clear the disabled bits in dl_x86_feature_1. */
> @@ -297,17 +196,21 @@ mprotect_failure:
> }
>
> #ifdef SHARED
> - if (program
> - && (!shstk_enabled
> - || enable_shstk_type != CET_PERMISSIVE)
> - && (ibt_enabled || shstk_enabled))
> + if (program && (ibt_enabled || shstk_enabled))
> {
> - /* Lock CET if IBT or SHSTK is enabled in executable. Don't
> - lock CET if SHSTK is enabled permissively. */
> - int res = dl_cet_lock_cet ();
> - if (res != 0)
> - _dl_fatal_printf ("%s: can't lock CET\n", program);
> + if ((!ibt_enabled
> + || enable_ibt_type != CET_PERMISSIVE)
> + && (!shstk_enabled
> + || enable_shstk_type != CET_PERMISSIVE))
> + {
> + /* Lock CET if IBT or SHSTK is enabled in executable unless
> + IBT or SHSTK is enabled permissively. */
> + int res = dl_cet_lock_cet ();
> + if (res != 0)
> + _dl_fatal_printf ("%s: can't lock CET\n", program);
OK.
> + }
>
> + /* Set feature_1 if IBT or SHSTK is enabled in executable. */
> cet_feature_changed = true;
> }
> #endif
> diff --git a/sysdeps/x86/dl-procruntime.c b/sysdeps/x86/dl-procruntime.c
> index fb36801f3e..5e39a38133 100644
> --- a/sysdeps/x86/dl-procruntime.c
> +++ b/sysdeps/x86/dl-procruntime.c
> @@ -54,15 +54,4 @@ PROCINFO_CLASS unsigned int _dl_x86_feature_1[2]
> # else
> ,
> # endif
> -
> -# if !defined PROCINFO_DECL && defined SHARED
> - ._dl_x86_legacy_bitmap
> -# else
> -PROCINFO_CLASS unsigned long _dl_x86_legacy_bitmap[2]
> -# endif
> -# if !defined SHARED || defined PROCINFO_DECL
> -;
> -# else
> -,
> -# endif
OK.
> #endif
> diff --git a/sysdeps/x86/tst-cet-legacy-4.c b/sysdeps/x86/tst-cet-legacy-4.c
> index a77078afc9..a922339333 100644
> --- a/sysdeps/x86/tst-cet-legacy-4.c
> +++ b/sysdeps/x86/tst-cet-legacy-4.c
> @@ -20,6 +20,9 @@
> #include <dlfcn.h>
> #include <stdio.h>
> #include <stdlib.h>
> +#include <string.h>
> +
> +#include <support/check.h>
>
> static int
> do_test (void)
> @@ -31,22 +34,18 @@ do_test (void)
> h = dlopen (modname, RTLD_LAZY);
> if (h == NULL)
> {
> - printf ("cannot open '%s': %s\n", modname, dlerror ());
> - exit (1);
> + const char *err = dlerror ();
> + if (!strstr (err, "rebuilt with IBT support needed"))
OK (needs adjustment if string is changed).
> + FAIL_EXIT1 ("incorrect dlopen '%s' error: %s\n", modname, err);
> + return 0;
> }
>
> fp = dlsym (h, "test");
> if (fp == NULL)
> - {
> - printf ("cannot get symbol 'test': %s\n", dlerror ());
> - exit (1);
> - }
> + FAIL_EXIT1 ("cannot get symbol 'test': %s\n", dlerror ());
>
> if (fp () != 0)
> - {
> - puts ("test () != 0");
> - exit (1);
> - }
> + FAIL_EXIT1 ("test () != 0");
>
> dlclose (h);
>
> diff --git a/sysdeps/x86/tst-cet-legacy-5.c b/sysdeps/x86/tst-cet-legacy-5.c
> index 6c9bba06f5..350c7e41df 100644
> --- a/sysdeps/x86/tst-cet-legacy-5.c
> +++ b/sysdeps/x86/tst-cet-legacy-5.c
> @@ -35,7 +35,7 @@ do_test_1 (const char *modname, bool fail)
> if (fail)
> {
> const char *err = dlerror ();
> - if (strstr (err, "shadow stack isn't enabled") == NULL)
> + if (strstr (err, "rebuilt with SHSTK support needed") == NULL)
OK (also needs adjustment)
> {
> printf ("incorrect dlopen '%s' error: %s\n", modname,
> err);
> diff --git a/sysdeps/x86/tst-cet-legacy-6.c b/sysdeps/x86/tst-cet-legacy-6.c
> index 877e77747d..9f2748fcb6 100644
> --- a/sysdeps/x86/tst-cet-legacy-6.c
> +++ b/sysdeps/x86/tst-cet-legacy-6.c
> @@ -35,7 +35,7 @@ do_test_1 (const char *modname, bool fail)
> if (fail)
> {
> const char *err = dlerror ();
> - if (strstr (err, "shadow stack isn't enabled") == NULL)
> + if (strstr (err, "rebuilt with SHSTK support needed") == NULL)
OK. (also needs adjustment)
> {
> printf ("incorrect dlopen '%s' error: %s\n", modname,
> err);
> diff --git a/sysdeps/x86/tst-cet-legacy-7.c b/sysdeps/x86/tst-cet-legacy-7.c
> new file mode 100644
> index 0000000000..cf4c2779ce
> --- /dev/null
> +++ b/sysdeps/x86/tst-cet-legacy-7.c
> @@ -0,0 +1,36 @@
> +/* Check compatibility of legacy executable with a JIT engine.
> + Copyright (C) 2020 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library 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
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <stdio.h>
> +#include <sys/mman.h>
> +#include <support/xunistd.h>
> +
Needs a pargraph explaining what this test is supposed to do.
I expect this test is supposed to just pass and not fail because it's
run with -fcf-protection=none.
What about the equivalent test to test for failure?
> +static int
> +do_test (void)
> +{
> + void (*funcp) (void);
> + funcp = xmmap (NULL, 0x1000, PROT_EXEC | PROT_READ | PROT_WRITE,
> + MAP_ANONYMOUS | MAP_PRIVATE, -1);
> + printf ("mmap = %p\n", funcp);
> + /* Write RET instruction. */
> + *(char *) funcp = 0xc3;
> + funcp ();
> + return 0;
OK.
> +}
> +
> +#include <support/test-driver.c>
> -- 2.24.1
--
Cheers,
Carlos.
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