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boringssl/crypto/cpu-x86-asm.pl
Adam Langley ad1907fe73 Use asm directives to protect OPENSSL_cleanse. 
Compilers have a bad habit of removing "superfluous" memset calls that
are trying to zero memory. For example, when memset()ing a buffer and
then free()ing it, the compiler might decide that the memset is
unobservable and thus can be removed.

Previously we tried to stop this by a) implementing memset in assembly
on x86 and b) putting the function in its own file for other platforms.

This change removes those tricks in favour of using asm directives to
scare the compiler away. As best as our compiler folks can tell, this is
sufficient and will continue to be so.

Change-Id: I40e0a62c3043038bafd8c63a91814a75a3c59269
Reviewed-on: https://boringssl-review.googlesource.com/1339
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
2014-07-31 18:49:22 +00:00

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#!/usr/bin/env perl
$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
push(@INC, "${dir}perlasm", "perlasm");
require "x86asm.pl";
&asm_init($ARGV[0],"crypto/cpu-x86-asm");
for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
&function_begin("OPENSSL_ia32_cpuid");
&xor ("edx","edx");
&pushf ();
&pop ("eax");
&mov ("ecx","eax");
&xor ("eax",1<<21);
&push ("eax");
&popf ();
&pushf ();
&pop ("eax");
&xor ("ecx","eax");
&xor ("eax","eax");
&bt ("ecx",21);
&jnc (&label("nocpuid"));
&mov ("esi",&wparam(0));
&mov (&DWP(8,"esi"),"eax"); # clear 3rd word
&cpuid ();
&mov ("edi","eax"); # max value for standard query level
&xor ("eax","eax");
&cmp ("ebx",0x756e6547); # "Genu"
&setne (&LB("eax"));
&mov ("ebp","eax");
&cmp ("edx",0x49656e69); # "ineI"
&setne (&LB("eax"));
&or ("ebp","eax");
&cmp ("ecx",0x6c65746e); # "ntel"
&setne (&LB("eax"));
&or ("ebp","eax"); # 0 indicates Intel CPU
&jz (&label("intel"));
&cmp ("ebx",0x68747541); # "Auth"
&setne (&LB("eax"));
&mov ("esi","eax");
&cmp ("edx",0x69746E65); # "enti"
&setne (&LB("eax"));
&or ("esi","eax");
&cmp ("ecx",0x444D4163); # "cAMD"
&setne (&LB("eax"));
&or ("esi","eax"); # 0 indicates AMD CPU
&jnz (&label("intel"));
# AMD specific
&mov ("eax",0x80000000);
&cpuid ();
&cmp ("eax",0x80000001);
&jb (&label("intel"));
&mov ("esi","eax");
&mov ("eax",0x80000001);
&cpuid ();
&or ("ebp","ecx");
&and ("ebp",1<<11|1); # isolate XOP bit
&cmp ("esi",0x80000008);
&jb (&label("intel"));
&mov ("eax",0x80000008);
&cpuid ();
&movz ("esi",&LB("ecx")); # number of cores - 1
&inc ("esi"); # number of cores
&mov ("eax",1);
&xor ("ecx","ecx");
&cpuid ();
&bt ("edx",28);
&jnc (&label("generic"));
&shr ("ebx",16);
&and ("ebx",0xff);
&cmp ("ebx","esi");
&ja (&label("generic"));
&and ("edx",0xefffffff); # clear hyper-threading bit
&jmp (&label("generic"));
&set_label("intel");
&cmp ("edi",7);
&jb (&label("cacheinfo"));
&mov ("esi",&wparam(0));
&mov ("eax",7);
&xor ("ecx","ecx");
&cpuid ();
&mov (&DWP(8,"esi"),"ebx");
&set_label("cacheinfo");
&cmp ("edi",4);
&mov ("edi",-1);
&jb (&label("nocacheinfo"));
&mov ("eax",4);
&mov ("ecx",0); # query L1D
&cpuid ();
&mov ("edi","eax");
&shr ("edi",14);
&and ("edi",0xfff); # number of cores -1 per L1D
&set_label("nocacheinfo");
&mov ("eax",1);
&xor ("ecx","ecx");
&cpuid ();
&and ("edx",0xbfefffff); # force reserved bits #20, #30 to 0
&cmp ("ebp",0);
&jne (&label("notintel"));
&or ("edx",1<<30); # set reserved bit#30 on Intel CPUs
&and (&HB("eax"),15); # familiy ID
&cmp (&HB("eax"),15); # P4?
&jne (&label("notintel"));
&or ("edx",1<<20); # set reserved bit#20 to engage RC4_CHAR
&set_label("notintel");
&bt ("edx",28); # test hyper-threading bit
&jnc (&label("generic"));
&and ("edx",0xefffffff);
&cmp ("edi",0);
&je (&label("generic"));
&or ("edx",0x10000000);
&shr ("ebx",16);
&cmp (&LB("ebx"),1);
&ja (&label("generic"));
&and ("edx",0xefffffff); # clear hyper-threading bit if not
&set_label("generic");
&and ("ebp",1<<11); # isolate AMD XOP flag
&and ("ecx",0xfffff7ff); # force 11th bit to 0
&mov ("esi","edx");
&or ("ebp","ecx"); # merge AMD XOP flag
&bt ("ecx",27); # check OSXSAVE bit
&jnc (&label("clear_avx"));
&xor ("ecx","ecx");
&data_byte(0x0f,0x01,0xd0); # xgetbv
&and ("eax",6);
&cmp ("eax",6);
&je (&label("done"));
&cmp ("eax",2);
&je (&label("clear_avx"));
&set_label("clear_xmm");
&and ("ebp",0xfdfffffd); # clear AESNI and PCLMULQDQ bits
&and ("esi",0xfeffffff); # clear FXSR
&set_label("clear_avx");
&and ("ebp",0xefffe7ff); # clear AVX, FMA and AMD XOP bits
&mov ("edi",&wparam(0));
&and (&DWP(8,"edi"),0xffffffdf); # clear AVX2
&set_label("done");
&mov ("eax","esi");
&mov ("edx","ebp");
&set_label("nocpuid");
&function_end("OPENSSL_ia32_cpuid");
&external_label("OPENSSL_ia32cap_P");
&function_begin_B("OPENSSL_rdtsc","EXTRN\t_OPENSSL_ia32cap_P:DWORD");
&xor ("eax","eax");
&xor ("edx","edx");
&picmeup("ecx","OPENSSL_ia32cap_P");
&bt (&DWP(0,"ecx"),4);
&jnc (&label("notsc"));
&rdtsc ();
&set_label("notsc");
&ret ();
&function_end_B("OPENSSL_rdtsc");
# This works in Ring 0 only [read DJGPP+MS-DOS+privileged DPMI host],
# but it's safe to call it on any [supported] 32-bit platform...
# Just check for [non-]zero return value...
&function_begin_B("OPENSSL_instrument_halt","EXTRN\t_OPENSSL_ia32cap_P:DWORD");
&picmeup("ecx","OPENSSL_ia32cap_P");
&bt (&DWP(0,"ecx"),4);
&jnc (&label("nohalt")); # no TSC
&data_word(0x9058900e); # push %cs; pop %eax
&and ("eax",3);
&jnz (&label("nohalt")); # not enough privileges
&pushf ();
&pop ("eax");
&bt ("eax",9);
&jnc (&label("nohalt")); # interrupts are disabled
&rdtsc ();
&push ("edx");
&push ("eax");
&halt ();
&rdtsc ();
&sub ("eax",&DWP(0,"esp"));
&sbb ("edx",&DWP(4,"esp"));
&add ("esp",8);
&ret ();
&set_label("nohalt");
&xor ("eax","eax");
&xor ("edx","edx");
&ret ();
&function_end_B("OPENSSL_instrument_halt");
# Essentially there is only one use for this function. Under DJGPP:
#
# #include <go32.h>
# ...
# i=OPENSSL_far_spin(_dos_ds,0x46c);
# ...
# to obtain the number of spins till closest timer interrupt.
&function_begin_B("OPENSSL_far_spin");
&pushf ();
&pop ("eax");
&bt ("eax",9);
&jnc (&label("nospin")); # interrupts are disabled
&mov ("eax",&DWP(4,"esp"));
&mov ("ecx",&DWP(8,"esp"));
&data_word (0x90d88e1e); # push %ds, mov %eax,%ds
&xor ("eax","eax");
&mov ("edx",&DWP(0,"ecx"));
&jmp (&label("spin"));
&align (16);
&set_label("spin");
&inc ("eax");
&cmp ("edx",&DWP(0,"ecx"));
&je (&label("spin"));
&data_word (0x1f909090); # pop %ds
&ret ();
&set_label("nospin");
&xor ("eax","eax");
&xor ("edx","edx");
&ret ();
&function_end_B("OPENSSL_far_spin");
&function_begin_B("OPENSSL_wipe_cpu","EXTRN\t_OPENSSL_ia32cap_P:DWORD");
&xor ("eax","eax");
&xor ("edx","edx");
&picmeup("ecx","OPENSSL_ia32cap_P");
&mov ("ecx",&DWP(0,"ecx"));
&bt (&DWP(0,"ecx"),1);
&jnc (&label("no_x87"));
if ($sse2) {
&and ("ecx",1<<26|1<<24); # check SSE2 and FXSR bits
&cmp ("ecx",1<<26|1<<24);
&jne (&label("no_sse2"));
&pxor ("xmm0","xmm0");
&pxor ("xmm1","xmm1");
&pxor ("xmm2","xmm2");
&pxor ("xmm3","xmm3");
&pxor ("xmm4","xmm4");
&pxor ("xmm5","xmm5");
&pxor ("xmm6","xmm6");
&pxor ("xmm7","xmm7");
&set_label("no_sse2");
}
# just a bunch of fldz to zap the fp/mm bank followed by finit...
&data_word(0xeed9eed9,0xeed9eed9,0xeed9eed9,0xeed9eed9,0x90e3db9b);
&set_label("no_x87");
&lea ("eax",&DWP(4,"esp"));
&ret ();
&function_end_B("OPENSSL_wipe_cpu");
&function_begin_B("OPENSSL_atomic_add");
&mov ("edx",&DWP(4,"esp")); # fetch the pointer, 1st arg
&mov ("ecx",&DWP(8,"esp")); # fetch the increment, 2nd arg
&push ("ebx");
&nop ();
&mov ("eax",&DWP(0,"edx"));
&set_label("spin");
&lea ("ebx",&DWP(0,"eax","ecx"));
&nop ();
&data_word(0x1ab10ff0); # lock; cmpxchg %ebx,(%edx) # %eax is envolved and is always reloaded
&jne (&label("spin"));
&mov ("eax","ebx"); # OpenSSL expects the new value
&pop ("ebx");
&ret ();
&function_end_B("OPENSSL_atomic_add");
# This function can become handy under Win32 in situations when
# we don't know which calling convention, __stdcall or __cdecl(*),
# indirect callee is using. In C it can be deployed as
#
#ifdef OPENSSL_CPUID_OBJ
# type OPENSSL_indirect_call(void *f,...);
# ...
# OPENSSL_indirect_call(func,[up to $max arguments]);
#endif
#
# (*) it's designed to work even for __fastcall if number of
# arguments is 1 or 2!
&function_begin_B("OPENSSL_indirect_call");
{
my ($max,$i)=(7,); # $max has to be chosen as 4*n-1
# in order to preserve eventual
# stack alignment
&push ("ebp");
&mov ("ebp","esp");
&sub ("esp",$max*4);
&mov ("ecx",&DWP(12,"ebp"));
&mov (&DWP(0,"esp"),"ecx");
&mov ("edx",&DWP(16,"ebp"));
&mov (&DWP(4,"esp"),"edx");
for($i=2;$i<$max;$i++)
{
# Some copies will be redundant/bogus...
&mov ("eax",&DWP(12+$i*4,"ebp"));
&mov (&DWP(0+$i*4,"esp"),"eax");
}
&call_ptr (&DWP(8,"ebp"));# make the call...
&mov ("esp","ebp"); # ... and just restore the stack pointer
# without paying attention to what we called,
# (__cdecl *func) or (__stdcall *one).
&pop ("ebp");
&ret ();
}
&function_end_B("OPENSSL_indirect_call");
&function_begin_B("OPENSSL_ia32_rdrand");
&mov ("ecx",8);
&set_label("loop");
&rdrand ("eax");
&jc (&label("break"));
&loop (&label("loop"));
&set_label("break");
&cmp ("eax",0);
&cmove ("eax","ecx");
&ret ();
&function_end_B("OPENSSL_ia32_rdrand");
&hidden("OPENSSL_ia32cap_P");
&asm_finish();
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