src/x86/win64.S


Log

Author Commit Date CI Message
Madhavan T. Venkataraman 9ba55921 2021-03-05T10:07:30 Static tramp v5 (#624) * Static Trampolines Closure Trampoline Security Issue ================================= Currently, the trampoline code used in libffi is not statically defined in a source file (except for MACH). The trampoline is either pre-defined machine code in a data buffer. Or, it is generated at runtime. In order to execute a trampoline, it needs to be placed in a page with executable permissions. Executable data pages are attack surfaces for attackers who may try to inject their own code into the page and contrive to have it executed. The security settings in a system may prevent various tricks used in user land to write code into a page and to have it executed somehow. On such systems, libffi trampolines would not be able to run. Static Trampoline ================= To solve this problem, the trampoline code needs to be defined statically in a source file, compiled and placed in the text segment so it can be mapped and executed naturally without any tricks. However, the trampoline needs to be able to access the closure pointer at runtime. PC-relative data referencing ============================ The solution implemented in this patch set uses PC-relative data references. The trampoline is mapped in a code page. Adjacent to the code page, a data page is mapped that contains the parameters of the trampoline: - the closure pointer - pointer to the ABI handler to jump to The trampoline code uses an offset relative to its current PC to access its data. Some architectures support PC-relative data references in the ISA itself. E.g., X64 supports RIP-relative references. For others, the PC has to somehow be loaded into a general purpose register to do PC-relative data referencing. To do this, we need to define a get_pc() kind of function and call it to load the PC in a desired register. There are two cases: 1. The call instruction pushes the return address on the stack. In this case, get_pc() will extract the return address from the stack and load it in the desired register and return. 2. The call instruction stores the return address in a designated register. In this case, get_pc() will copy the return address to the desired register and return. Either way, the PC next to the call instruction is obtained. Scratch register ================ In order to do its job, the trampoline code would need to use a scratch register. Depending on the ABI, there may not be a register available for scratch. This problem needs to be solved so that all ABIs will work. The trampoline will save two values on the stack: - the closure pointer - the original value of the scratch register This is what the stack will look like: sp before trampoline ------> -------------------- | closure pointer | -------------------- | scratch register | sp after trampoline -------> -------------------- The ABI handler can do the following as needed by the ABI: - the closure pointer can be loaded in a desired register - the scratch register can be restored to its original value - the stack pointer can be restored to its original value (the value when the trampoline was invoked) To do this, I have defined prolog code for each ABI handler. The legacy trampoline jumps to the ABI handler directly. But the static trampoline defined in this patch jumps tp the prolog code which performs the above actions before jumping to the ABI handler. Trampoline Table ================ In order to reduce the trampoline memory footprint, the trampoline code would be defined as a code array in the text segment. This array would be mapped into the address space of the caller. The mapping would, therefore, contain a trampoline table. Adjacent to the trampoline table mapping, there will be a data mapping that contains a parameter table, one parameter block for each trampoline. The parameter block will contain: - a pointer to the closure - a pointer to the ABI handler The static trampoline code would finally look like this: - Make space on the stack for the closure and the scratch register by moving the stack pointer down - Store the original value of the scratch register on the stack - Using PC-relative reference, get the closure pointer - Store the closure pointer on the stack - Using PC-relative reference, get the ABI handler pointer - Jump to the ABI handler Mapping size ============ The size of the code mapping that contains the trampoline table needs to be determined on a per architecture basis. If a particular architecture supports multiple base page sizes, then the largest supported base page size needs to be chosen. E.g., we choose 16K for ARM64. Trampoline allocation and free ============================== Static trampolines are allocated in ffi_closure_alloc() and freed in ffi_closure_free(). Normally, applications use these functions. But there are some cases out there where the user of libffi allocates and manages its own closure memory. In such cases, static trampolines cannot be used. These will fall back to using legacy trampolines. The user has to make sure that the memory is executable. ffi_closure structure ===================== I did not want to make any changes to the size of the closure structure for this feature to guarantee compatibility. But the opaque static trampoline handle needs to be stored in the closure. I have defined it as follows: - char tramp[FFI_TRAMPOLINE_SIZE]; + union { + char tramp[FFI_TRAMPOLINE_SIZE]; + void *ftramp; + }; If static trampolines are used, then tramp[] is not needed to store a dynamic trampoline. That space can be reused to store the handle. Hence, the union. Architecture Support ==================== Support has been added for x64, i386, aarch64 and arm. Support for other architectures can be added very easily in the future. OS Support ========== Support has been added for Linux. Support for other OSes can be added very easily. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> * x86: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code mapping and data mapping sizes. - Define the trampoline code table statically. Define two tables, actually, one with CET and one without. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_unix64 - ffi_closure_unix64_sse - ffi_closure_win64 The prolog functions are called: - ffi_closure_unix64_alt - ffi_closure_unix64_sse_alt - ffi_closure_win64_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> * i386: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code table statically. Define two tables, actually, one with CET and one without. - Define the trampoline code table statically. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_i386 - ffi_closure_STDCALL - ffi_closure_REGISTER The prolog functions are called: - ffi_closure_i386_alt - ffi_closure_STDCALL_alt - ffi_closure_REGISTER_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> * arm64: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code mapping and data mapping sizes. - Define the trampoline code table statically. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_SYSV - ffi_closure_SYSV_V The prolog functions are called: - ffi_closure_SYSV_alt - ffi_closure_SYSV_V_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> * arm: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code mapping and data mapping sizes. - Define the trampoline code table statically. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_SYSV - ffi_closure_VFP The prolog functions are called: - ffi_closure_SYSV_alt - ffi_closure_VFP_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Mike Hommey d817d0da 2020-11-10T20:39:25 Don't use FFI_TYPE_LONGDOUBLE in the jump table in win64*.S (#580) It may have the same value as FFI_TYPE_DOUBLE per ffi.h, which possibly can make things go wrong with .org/ORG. For instance, GCC complains about "Error: attempt to move .org backwards"
hjl-tools 78556561 2020-02-21T19:08:06 x86: Add indirect branch tracking support (#540) Intel Control-flow Enforcement Technology (CET): https://software.intel.com/en-us/articles/intel-sdm contains shadow stack (SHSTK) and indirect branch tracking (IBT). When CET is enabled, ELF object files must be marked with .note.gnu.property section. When Intel CET is enabled, include <cet.h> in assembly codes to mark Intel CET support. Also when IBT is enabled, all indirect branch targets must start with ENDBR instruction and notrack prefix can be used to disable IBT on indirect branch. <cet.h> defines _CET_ENDBR which can be used in assembly codes for ENDBR instruction. If <cet.h> isn't included, define _CET_ENDBR as empty so that _CET_ENDBR can be used in assembly codes. Trampoline must be enlarged to add ENDBR instruction unconditionally, which is NOP on non-CET processors. This is required regardless if libffi is enabled with CET since libffi.so will be marked in legacy bitmap, but trampoline won't. Update library version for larger FFI_TRAMPOLINE_SIZE. This fixed: https://github.com/libffi/libffi/issues/474 Tested with $ CC="gcc -Wl,-z,cet-report=error -fcf-protection" CXX="g++ -Wl,-z,cet-report=error -fcf-protection" .../configure on Linux CET machines in i686, x32 and x86-64 modes.
Jeremy Huddleston Sequoia 05a17964 2019-02-19T04:11:28 Cleanup symbol exports on darwin and add architecture preprocessor checks to assist in building fat binaries (eg: i386+x86_64 on macOS or arm+aarch64 on iOS) (#450) * x86: Ensure _efi64 suffixed symbols are not exported * x86: Ensure we do not export ffi_prep_cif_machdep Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * x86: Ensure we don't export ffi_call_win64, ffi_closure_win64, or ffi_go_closure_win64 Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * closures: Silence a semantic warning libffi/src/closures.c:175:23: This function declaration is not a prototype Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * aarch64: Ensure we don't export ffi_prep_cif_machdep Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * arm: Ensure we don't export ffi_prep_cif_machdep Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * aarch64, arm, x86: Add architecture preprocessor checks to support easier fat builds (eg: iOS) Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * x86: Silence some static analysis warnings libffi/src/x86/ffi64.c:286:21: The left operand of '!=' is a garbage value due to array index out of bounds libffi/src/x86/ffi64.c:297:22: The left operand of '!=' is a garbage value due to array index out of bounds Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * aarch: Use FFI_HIDDEN rather than .hidden Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com> * ffi.h: Don't advertise ffi_java_rvalue_to_raw, ffi_prep_java_raw_closure, and ffi_prep_java_raw_closure_loc when FFI_NATIVE_RAW_API is 0 Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Anthony Green b5ee3957 2018-05-05T07:41:53 Revert "Remove some symbol exports and cleanup newline warnings (#433)" This reverts commit a5a0f3cf36dfb4d64316414a872288c3170e6c1d.
Jeremy Huddleston Sequoia a5a0f3cf 2018-05-05T03:44:33 Remove some symbol exports and cleanup newline warnings (#433) * build: Ensure darwin generated sources end with a new line Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@macports.org> * build: Use .private_extern where missing to prevent exporting symbols that are not API Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@macports.org>
jon d15581c6 2017-12-01T00:34:30 Updating calls to ffi_closure_unix64_inner and ffi_closure_win64_inner to use PLT. Without this fix, statically linking libffi causes the linker error i.e. 'requires dynamic R_X86_64_PC32 reloc against ffi_closure_unix64_inner which may overflow at runtime; recompile with -fPIC)'
Richard Henderson 794a54d4 2016-06-05T14:57:00 Mark win64.S with GNU-stack note
Iain Sandoe 92810b4b 2016-05-26T08:56:51 [Darwin-x86, build] Fix up label prefixes, remove .purgem Darwin uses a label prefix of _. cctools assembler will not accept .purgem as a directive.
Richard Henderson e5843a3a 2016-04-15T16:10:08 x86: Fix calling convention for ffi_closure_win64_inner Also enable testing for the cross-abi calls.
Richard Henderson d0675197 2016-03-07T12:14:22 x86: Copy fix for clang .org from unix64.S Clang doesn't understand .org with symbolic operands.
Josh Triplett eaa59755 2015-07-26T17:17:16 src/x86/win64.S: Handle name mangling and PIC Move the macros from unix64.S into a shared header asmnames.h and use them in win64.S too.
Josh Triplett c8e82d9f 2015-07-26T16:18:57 src/x86/win64.S: Support compiling on non-WIN64 platforms Non-WIN64 versions of the GNU assembler don't support the .seh_* directives for structured exception handling, so wrap them in a macro that compiles to nothing. Handle the registers used for the non-Windows x86-64 calling convention when on a non-Windows platform. Distinguish between cases that should refer to the native argument registers (defined as arg0, arg1, arg2, and arg3) and cases that should always refer to the Windows argument registers.
Richard Henderson 99db4d42 2014-10-23T14:12:18 win64: Rewrite It's way too different from the 32-bit ABIs with which it is currently associated. As seen from all of the existing XFAILs.
Bernd Edlinger bfcbf329 2014-09-20T06:51:45 2014-05-11 Bernd Edlinger <bernd.edlinger@hotmail.de> Fix current cygwin-64 build problems. * src/java_raw_api.c: Remove if !defined(FFI_NO_RAW_API). * src/x86/ffi.c: Add if defined(__CYGWIN__). * src/x86/win64.S (ffi_closure_win64, ffi_call_win64): Added handling for FFI_TYPE_UINT64, FFI_TYPE_POINTER and FFI_TYPE_INT. Added SEH information. Fixed formatting.
Anthony Green 5b9cd527 2010-11-22T15:19:57 win64-underscore patch
Anthony Green c6dddbd0 2009-10-04T08:11:33 Initial commit