The CET is only supported for x86_64 and there is no plan to add
kernel support for i386. Move the Makefile rules and files from the
generic x86 folder to x86_64 one.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Resolves: BZ # 31221
glibc can recognise its code, but does not have its data.
This patch remedies that.
Signed-off-by: Janet Blackquill <uhhadd@gmail.com>
PLT rewrite calculated displacement with
ElfW(Addr) disp = value - branch_start - JMP32_INSN_SIZE;
On x32, displacement from 0xf7fbe060 to 0x401030 was calculated as
unsigned int disp = 0x401030 - 0xf7fbe060 - 5;
with disp == 0x8442fcb and caused displacement overflow. The PLT entry
was changed to:
0xf7fbe060 <+0>: e9 cb 2f 44 08 jmp 0x401030
0xf7fbe065 <+5>: cc int3
0xf7fbe066 <+6>: cc int3
0xf7fbe067 <+7>: cc int3
0xf7fbe068 <+8>: cc int3
0xf7fbe069 <+9>: cc int3
0xf7fbe06a <+10>: cc int3
0xf7fbe06b <+11>: cc int3
0xf7fbe06c <+12>: cc int3
0xf7fbe06d <+13>: cc int3
0xf7fbe06e <+14>: cc int3
0xf7fbe06f <+15>: cc int3
x32 has 32-bit address range, but it doesn't wrap address around at 4GB,
JMP target was changed to 0x100401030 (0xf7fbe060LL + 0x8442fcbLL + 5),
which is above 4GB.
Always use uint64_t to calculate displacement. This fixes BZ #31218.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
With gcc 6.5.0, 7.5.0, 8.5.0, and 9.5.0 the tst-stdbit-Wconversion
issues the warnings:
../stdlib/stdbit.h: In function ‘__clo16_inline’:
../stdlib/stdbit.h:128:26: error: conversion to ‘uint16_t {aka short
unsigned int}’ from ‘int’ may alter its value [-Werror=conversion]
return __clz16_inline (~__x);
^
../stdlib/stdbit.h: In function ‘__clo8_inline’:
../stdlib/stdbit.h:134:25: error: conversion to ‘uint8_t {aka unsigned
char}’ from ‘int’ may alter its value [-Werror=conversion]
return __clz8_inline (~__x);
^
../stdlib/stdbit.h: In function ‘__cto16_inline’:
../stdlib/stdbit.h:232:26: error: conversion to ‘uint16_t {aka short
unsigned int}’ from ‘int’ may alter its value [-Werror=conversion]
return __ctz16_inline (~__x);
^
../stdlib/stdbit.h: In function ‘__cto8_inline’:
../stdlib/stdbit.h:238:25: error: conversion to ‘uint8_t {aka unsigned
char}’ from ‘int’ may alter its value [-Werror=conversion]
return __ctz8_inline (~__x);
^
../stdlib/stdbit.h: In function ‘__bf16_inline’:
../stdlib/stdbit.h:701:23: error: conversion to ‘uint16_t {aka short
unsigned int}’ from ‘int’ may alter its value [-Werror=conversion]
return __x == 0 ? 0 : ((uint16_t) 1) << (__bw16_inline (__x) - 1);
~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../stdlib/stdbit.h: In function ‘__bf8_inline’:
../stdlib/stdbit.h:707:23: error: conversion to ‘uint8_t {aka unsigned
char}’ from ‘int’ may alter its value [-Werror=conversion]
return __x == 0 ? 0 : ((uint8_t) 1) << (__bw8_inline (__x) - 1);
~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../stdlib/stdbit.h: In function ‘__bc16_inline’:
../stdlib/stdbit.h:751:59: error: conversion to ‘uint16_t {aka short
unsigned int}’ from ‘int’ may alter its value [-Werror=conversion]
return __x <= 1 ? 1 : ((uint16_t) 2) << (__bw16_inline (__x - 1) -
1);
^~~
../stdlib/stdbit.h:751:23: error: conversion to ‘uint16_t {aka short
unsigned int}’ from ‘int’ may alter its value [-Werror=conversion]
return __x <= 1 ? 1 : ((uint16_t) 2) << (__bw16_inline (__x - 1) -
1);
~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../stdlib/stdbit.h: In function ‘__bc8_inline’:
../stdlib/stdbit.h:757:57: error: conversion to ‘uint8_t {aka unsigned
char}’ from ‘int’ may alter its value [-Werror=conversion]
return __x <= 1 ? 1 : ((uint8_t) 2) << (__bw8_inline (__x - 1) - 1);
^~~
../stdlib/stdbit.h:757:23: error: conversion to ‘uint8_t {aka unsigned
char}’ from ‘int’ may alter its value [-Werror=conversion]
return __x <= 1 ? 1 : ((uint8_t) 2) << (__bw8_inline (__x - 1) - 1);
It seems to boiler down to __builtin_clz not having a variant for 8 or
16 bits. Fix it by explicit casting to the expected types.
Checked on x86_64-linux-gnu and i686-linux-gnu with gcc 9.5.0.
Add ELF_DYNAMIC_AFTER_RELOC to allow target specific processing after
relocation.
For x86-64, add
#define DT_X86_64_PLT (DT_LOPROC + 0)
#define DT_X86_64_PLTSZ (DT_LOPROC + 1)
#define DT_X86_64_PLTENT (DT_LOPROC + 3)
1. DT_X86_64_PLT: The address of the procedure linkage table.
2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage
table.
3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table
entry.
With the r_addend field of the R_X86_64_JUMP_SLOT relocation set to the
memory offset of the indirect branch instruction.
Define ELF_DYNAMIC_AFTER_RELOC for x86-64 to rewrite the PLT section
with direct branch after relocation when the lazy binding is disabled.
PLT rewrite is disabled by default since SELinux may disallow modifying
code pages and ld.so can't detect it in all cases. Use
$ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=1
to enable PLT rewrite with 32-bit direct jump at run-time or
$ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2
to enable PLT rewrite with 32-bit direct jump and on APX processors with
64-bit absolute jump at run-time.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
These describe generic AArch64 CPU features, and are not tied to a
kernel-specific way of determining them. We can share them between
the Linux and Hurd AArch64 ports.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240103171502.1358371-13-bugaevc@gmail.com>
We fetch __vm_page_size as the very first RPC that we do, inside
__mach_init (). Propagate that to _dl_pagesize ASAP after that,
before any other initialization.
In dynamic builds, this is already done immediately after
__mach_init (), inside _dl_sysdep_start ().
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240103171502.1358371-12-bugaevc@gmail.com>
This is the case on both x86 architectures, but not on AArch64.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240103171502.1358371-11-bugaevc@gmail.com>
We already have the RETURN_TO macro for this exact use case, and it's already
used in the non-static code path. Use it here too.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240103171502.1358371-9-bugaevc@gmail.com>
Instead of relying on the stack frame layout to figure out where the stack
pointer was prior to the _hurd_stack_setup () call, just pass the pointer
as an argument explicitly. This is less brittle and much more portable.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240103171502.1358371-8-bugaevc@gmail.com>
setcontext and swapcontext put a restore token on the old shadow stack
which is used to restore the target shadow stack when switching user
contexts. When longjmp from a user context, the target shadow stack
can be different from the current shadow stack and INCSSP can't be
used to restore the shadow stack pointer to the target shadow stack.
Update longjmp to search for a restore token. If found, use the token
to restore the shadow stack pointer before using INCSSP to pop the
shadow stack. Stop the token search and use INCSSP if the shadow stack
entry value is the same as the current shadow stack pointer.
It is a user error if there is a shadow stack switch without leaving a
restore token on the old shadow stack.
The only difference between __longjmp.S and __longjmp_chk.S is that
__longjmp_chk.S has a check for invalid longjmp usages. Merge
__longjmp.S and __longjmp_chk.S by adding the CHECK_INVALID_LONGJMP
macro.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Since shadow stack is only supported for x86-64, ignore --enable-cet for
i386. Always setting $(enable-cet) for i386 to "no" to support
ifneq ($(enable-cet),no)
in x86 Makefiles. We can't use
ifeq ($(enable-cet),yes)
since $(enable-cet) can be "yes", "no" or "permissive".
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
These symbols are internal and never exported; make sure the compiler
realizes that when compiling hurdsig.c and does not try to emit GOT
reads.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
C23 adds a header <stdbit.h> with various functions and type-generic
macros for bit-manipulation of unsigned integers (plus macro defines
related to endianness). Implement this header for glibc.
The functions have both inline definitions in the header (referenced
by macros defined in the header) and copies with external linkage in
the library (which are implemented in terms of those macros to avoid
duplication). They are documented in the glibc manual. Tests, as
well as verifying results for various inputs (of both the macros and
the out-of-line functions), verify the types of those results (which
showed up a bug in an earlier version with the type-generic macro
stdc_has_single_bit wrongly returning a promoted type), that the
macros can be used at top level in a source file (so don't use ({})),
that they evaluate their arguments exactly once, and that the macros
for the type-specific functions have the expected implicit conversions
to the relevant argument type.
Jakub previously referred to -Wconversion warnings in type-generic
macros, so I've included a test with -Wconversion (but the only
warnings I saw and fixed from that test were actually in inline
functions in the <stdbit.h> header - not anything coming from use of
the type-generic macros themselves).
This implementation of the type-generic macros does not handle
unsigned __int128, or unsigned _BitInt types with a width other than
that of a standard integer type (and C23 doesn't require the header to
handle such types either). Support for those types, using the new
type-generic built-in functions Jakub's added for GCC 14, can
reasonably be added in a followup (along of course with associated
tests).
This implementation doesn't do anything special to handle C++, or have
any tests of functionality in C++ beyond the existing tests that all
headers can be compiled in C++ code; it's not clear exactly what form
this header should take in C++, but probably not one using macros.
DIS ballot comment AT-107 asks for the word "count" to be added to the
names of the stdc_leading_zeros, stdc_leading_ones,
stdc_trailing_zeros and stdc_trailing_ones functions and macros. I
don't think it's likely to be accepted (accepting any technical
comments would mean having an FDIS ballot), but if it is accepted at
the WG14 meeting (22-26 January in Strasbourg, starting with DIS
ballot comment handling) then there would still be time to update
glibc for the renaming before the 2.39 release.
The new functions and header are placed in the stdlib/ directory in
glibc, rather than creating a new toplevel stdbit/ or putting them in
string/ alongside ffs.
Tested for x86_64 and x86.
Includes test for setcontext too.
The test directly checks after longjmp if ZA got disabled and the
ZA contents got saved following the lazy saving scheme. It does not
use ACLE code to verify that gcc can interoperate with glibc.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
