diff options
Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 98 |
1 files changed, 84 insertions, 14 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 4f79a92fc1d..1379502ebbb 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -11042,6 +11042,7 @@ the built-in function returns -1. @findex __builtin_alloca_with_align @findex __builtin_alloca_with_align_and_max @findex __builtin_call_with_static_chain +@findex __builtin_extend_pointer @findex __builtin_fpclassify @findex __builtin_isfinite @findex __builtin_isnormal @@ -12419,6 +12420,15 @@ Similar to @code{__builtin_bswap32}, except the argument and return types are 64 bit. @end deftypefn +@deftypefn {Built-in Function} Pmode __builtin_extend_pointer (void * x) +On targets where the user visible pointer size is smaller than the size +of an actual hardware address this function returns the extended user +pointer. Targets where this is true included ILP32 mode on x86_64 or +Aarch64. This function is mainly useful when writing inline assembly +code. +@var{addr} +@end deftypefn + @node Target Builtins @section Built-in Functions Specific to Particular Target Machines @@ -12461,6 +12471,7 @@ instructions, but allow the compiler to schedule those calls. * TILEPro Built-in Functions:: * x86 Built-in Functions:: * x86 transactional memory intrinsics:: +* x86 control-flow protection intrinsics:: @end menu @node AArch64 Built-in Functions @@ -19054,14 +19065,12 @@ vector unsigned short vec_vctzh (vector unsigned short); vector int vec_vctzw (vector int); vector unsigned int vec_vctzw (vector int); -long long vec_vextract4b (const vector signed char, const int); -long long vec_vextract4b (const vector unsigned char, const int); +vector unsigned long long vec_extract4b (vector unsigned char, const int); -vector signed char vec_insert4b (vector int, vector signed char, const int); +vector unsigned char vec_insert4b (vector signed int, vector unsigned char, + const int); vector unsigned char vec_insert4b (vector unsigned int, vector unsigned char, const int); -vector signed char vec_insert4b (long long, vector signed char, const int); -vector unsigned char vec_insert4b (long long, vector unsigned char, const int); vector unsigned int vec_parity_lsbb (vector signed int); vector unsigned int vec_parity_lsbb (vector unsigned int); @@ -21772,13 +21781,17 @@ void __builtin_ia32_wrpkru (unsigned int) unsigned int __builtin_ia32_rdpkru () @end smallexample -The following built-in functions are available when @option{-mcet} is used. -They are used to support Intel Control-flow Enforcment Technology (CET). -Each built-in function generates the machine instruction that is part of the -function's name. +The following built-in functions are available when @option{-mcet} or +@option{-mshstk} option is used. They support shadow stack +machine instructions from Intel Control-flow Enforcement Technology (CET). +Each built-in function generates the machine instruction that is part +of the function's name. These are the internal low-level functions. +Normally the functions in @ref{x86 control-flow protection intrinsics} +should be used instead. + @smallexample -unsigned int __builtin_ia32_rdsspd (unsigned int) -unsigned long long __builtin_ia32_rdsspq (unsigned long long) +unsigned int __builtin_ia32_rdsspd (void) +unsigned long long __builtin_ia32_rdsspq (void) void __builtin_ia32_incsspd (unsigned int) void __builtin_ia32_incsspq (unsigned long long) void __builtin_ia32_saveprevssp(void); @@ -21885,6 +21898,51 @@ else Note that, in most cases, the transactional and non-transactional code must synchronize together to ensure consistency. +@node x86 control-flow protection intrinsics +@subsection x86 Control-Flow Protection Intrinsics + +@deftypefn {CET Function} {ret_type} _get_ssp (void) +Get the current value of shadow stack pointer if shadow stack support +from Intel CET is enabled in the hardware or @code{0} otherwise. +The @code{ret_type} is @code{unsigned long long} for 64-bit targets +and @code{unsigned int} for 32-bit targets. +@end deftypefn + +@deftypefn {CET Function} void _inc_ssp (unsigned int) +Increment the current shadow stack pointer by the size specified by the +function argument. The argument is masked to a byte value for security +reasons, so to increment by more than 255 bytes you must call the function +multiple times. +@end deftypefn + +The shadow stack unwind code looks like: + +@smallexample +#include <immintrin.h> + +/* Unwind the shadow stack for EH. */ +#define _Unwind_Frames_Extra(x) \ + do \ + @{ \ + _Unwind_Word ssp = _get_ssp (); \ + if (ssp != 0) \ + @{ \ + _Unwind_Word tmp = (x); \ + while (tmp > 255) \ + @{ \ + _inc_ssp (tmp); \ + tmp -= 255; \ + @} \ + _inc_ssp (tmp); \ + @} \ + @} \ + while (0) +@end smallexample + +@noindent +This code runs unconditionally on all 64-bit processors. For 32-bit +processors the code runs on those that support multi-byte NOP instructions. + @node Target Format Checks @section Format Checks Specific to Particular Target Machines @@ -23831,11 +23889,23 @@ deprecated. @xref{Deprecated Features}. @table @code @item For scope -If a variable is declared at for scope, it used to remain in scope until -the end of the scope that contained the for statement (rather than just -within the for scope). G++ retains this, but issues a warning, if such a +If a variable is declared at for scope, it used to remain in scope +until the end of the scope that contained the for statement (rather +than just within the for scope). The deprecated +@option{-fno-for-scope} option enables this non-standard behavior. +Without the option, G++ retains this, but issues a warning, if such a variable is accessed outside the for scope. +The behavior is deprecated, only available with @option{-std=c++98} +@option{-std=gnu++98} languages and you must use the +@option{-fpermissive} option to enable it. The behavior will be +removed. + +@item Friend Injection +The @option{-ffriend-injection} option makes injected friends visible +to regular name lookup, unlike standard C++. This option is +deprecated and will be removed. + @item Implicit C language Old C system header files did not contain an @code{extern "C" @{@dots{}@}} scope to set the language. On such systems, all header files are |