When delay loading a symbol, Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls GetProcAddress(), pops the saved registers and calls the function. This works fine if all of the parameters are ints. However, since it does not save xmm0 - 3, it relies on GetProcAddress() preserving these registers if the function takes floating point parameters.
Signed-off-by: Huw Davies huw@codeweavers.com --- dlls/kernel32/module.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-)
diff --git a/dlls/kernel32/module.c b/dlls/kernel32/module.c index b97c79b942..e57356632a 100644 --- a/dlls/kernel32/module.c +++ b/dlls/kernel32/module.c @@ -1363,7 +1363,7 @@ BOOL WINAPI DECLSPEC_HOTPATCH FreeLibrary(HINSTANCE hLibModule) * Success: A pointer to the symbol in the process address space. * Failure: NULL. Use GetLastError() to determine the cause. */ -FARPROC WINAPI GetProcAddress( HMODULE hModule, LPCSTR function ) +FARPROC get_proc_address( HMODULE hModule, LPCSTR function ) { NTSTATUS nts; FARPROC fp; @@ -1387,6 +1387,54 @@ FARPROC WINAPI GetProcAddress( HMODULE hModule, LPCSTR function ) return fp; }
+#ifdef __x86_64__ +/* + * Work around a Delphi bug on x86_64. When delay loading a symbol, + * Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls + * GetProcAddress(), pops the saved registers and calls the function. + * This works fine if all of the parameters are ints. However, since + * it does not save xmm0 - 3, it relies on GetProcAddress() preserving + * these registers if the function takes floating point parameters. + * This wrapper saves xmm0 - 3 to the stack. + */ +extern FARPROC get_proc_address_wrapper( HMODULE module, LPCSTR function ); + +__ASM_GLOBAL_FUNC( get_proc_address_wrapper, + "pushq %rbp\n\t" + __ASM_CFI(".cfi_adjust_cfa_offset 8\n\t") + __ASM_CFI(".cfi_rel_offset %rbp,0\n\t") + "movq %rsp,%rbp\n\t" + __ASM_CFI(".cfi_def_cfa_register %rbp\n\t") + "subq $0x40,%rsp\n\t" + "movaps %xmm0,-0x10(%rbp)\n\t" + "movaps %xmm1,-0x20(%rbp)\n\t" + "movaps %xmm2,-0x30(%rbp)\n\t" + "movaps %xmm3,-0x40(%rbp)\n\t" + "call _get_proc_address\n\t" + "movaps -0x40(%rbp), %xmm3\n\t" + "movaps -0x30(%rbp), %xmm2\n\t" + "movaps -0x20(%rbp), %xmm1\n\t" + "movaps -0x10(%rbp), %xmm0\n\t" + "movq %rbp,%rsp\n\t" + __ASM_CFI(".cfi_def_cfa_register %rsp\n\t") + "popq %rbp\n\t" + __ASM_CFI(".cfi_adjust_cfa_offset -8\n\t") + __ASM_CFI(".cfi_same_value %rbp\n\t") + "ret" ); +#else /* __x86_64__ */ + +static inline FARPROC get_proc_address_wrapper( HMODULE module, LPCSTR function ) +{ + return get_proc_address( module, function ); +} + +#endif /* __x86_64__ */ + +FARPROC WINAPI GetProcAddress( HMODULE hModule, LPCSTR function ) +{ + return get_proc_address_wrapper( hModule, function ); +} + /*********************************************************************** * DelayLoadFailureHook (KERNEL32.@) */
Am 06.02.2018 um 11:26 schrieb Huw Davies huw@codeweavers.com:
When delay loading a symbol, Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls GetProcAddress(), pops the saved registers and calls the function. This works fine if all of the parameters are ints. However, since it does not save xmm0 - 3, it relies on GetProcAddress() preserving these registers if the function takes floating point parameters.
This is mostly for me trying to understand things: What would make changes to those registers inside GetProcAddress? Afaics this function shouldn’t do anything floating point related.
On Tue, Feb 06, 2018 at 11:45:32AM +0100, Stefan Dösinger wrote:
Am 06.02.2018 um 11:26 schrieb Huw Davies huw@codeweavers.com:
When delay loading a symbol, Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls GetProcAddress(), pops the saved registers and calls the function. This works fine if all of the parameters are ints. However, since it does not save xmm0 - 3, it relies on GetProcAddress() preserving these registers if the function takes floating point parameters.
This is mostly for me trying to understand things: What would make changes to those registers inside GetProcAddress? Afaics this function shouldn’t do anything floating point related.
It doesn't need to be floating point operations. The compiler can used them as 128-bit registers, possibly for string-type operations.
Indeed a quick grep through ntdll shows that clang uses them in RtlIsTextUnicode(), for example.
Huw.
On Tue, Feb 06, 2018 at 11:29:46AM +0000, Huw Davies wrote:
On Tue, Feb 06, 2018 at 11:45:32AM +0100, Stefan Dösinger wrote:
Am 06.02.2018 um 11:26 schrieb Huw Davies huw@codeweavers.com:
When delay loading a symbol, Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls GetProcAddress(), pops the saved registers and calls the function. This works fine if all of the parameters are ints. However, since it does not save xmm0 - 3, it relies on GetProcAddress() preserving these registers if the function takes floating point parameters.
This is mostly for me trying to understand things: What would make changes to those registers inside GetProcAddress? Afaics this function shouldn’t do anything floating point related.
It doesn't need to be floating point operations. The compiler can used them as 128-bit registers, possibly for string-type operations.
Indeed a quick grep through ntdll shows that clang uses them in RtlIsTextUnicode(), for example.
Inlined memset and memcpy for instance translate to xmm usage these days.
Ciao, Marcus
Huw Davies huw@codeweavers.com writes:
When delay loading a symbol, Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls GetProcAddress(), pops the saved registers and calls the function. This works fine if all of the parameters are ints. However, since it does not save xmm0 - 3, it relies on GetProcAddress() preserving these registers if the function takes floating point parameters.
Is that really inside Delphi code? Don't we have the same bug in ours?
On Tue, Feb 06, 2018 at 03:03:27PM +0100, Alexandre Julliard wrote:
Huw Davies huw@codeweavers.com writes:
When delay loading a symbol, Delphi saves rcx, rdx, r8 and r9 to the stack. It then calls GetProcAddress(), pops the saved registers and calls the function. This works fine if all of the parameters are ints. However, since it does not save xmm0 - 3, it relies on GetProcAddress() preserving these registers if the function takes floating point parameters.
Is that really inside Delphi code? Don't we have the same bug in ours?
Yes, GetProcAddress is called from within Delphi code. And yes, it looks like we have the same bug in ours. I'll take a look at that.
Huw.
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Alexandre Julliard -
Huw Davies -
Marcus Meissner -
Stefan Dösinger