bn/asm/x86[_64]-mont*.pl: implement slightly alternative page-walking.

[openssl.git] / crypto / bn / asm / x86-mont.pl

diff --git a/crypto/bn/asm/x86-mont.pl b/crypto/bn/asm/x86-mont.pl
index 09296ec662d9adca149f7658f2a1f0086f209800..6787503666de94b38b35f2b4526427357f09cdeb 100755 (executable)
--- a/crypto/bn/asm/x86-mont.pl
+++ b/crypto/bn/asm/x86-mont.pl
@@ -73,27 +73,26 @@ $frame=32;                          # size of above frame rounded up to 16n
 
        &lea    ("esi",&wparam(0));     # put aside pointer to argument block
        &lea    ("edx",&wparam(1));     # load ap
-       &mov    ("ebp","esp");          # saved stack pointer!
        &add    ("edi",2);              # extra two words on top of tp
        &neg    ("edi");
-       &lea    ("esp",&DWP(-$frame,"esp","edi",4));    # alloca($frame+4*(num+2))
+       &lea    ("ebp",&DWP(-$frame,"esp","edi",4));    # future alloca($frame+4*(num+2))
        &neg    ("edi");
 
        # minimize cache contention by arraning 2K window between stack
        # pointer and ap argument [np is also position sensitive vector,
        # but it's assumed to be near ap, as it's allocated at ~same
        # time].
-       &mov    ("eax","esp");
+       &mov    ("eax","ebp");
        &sub    ("eax","edx");
        &and    ("eax",2047);
-       &sub    ("esp","eax");          # this aligns sp and ap modulo 2048
+       &sub    ("ebp","eax");          # this aligns sp and ap modulo 2048
 
-       &xor    ("edx","esp");
+       &xor    ("edx","ebp");
        &and    ("edx",2048);
        &xor    ("edx",2048);
-       &sub    ("esp","edx");          # this splits them apart modulo 4096
+       &sub    ("ebp","edx");          # this splits them apart modulo 4096
 
-       &and    ("esp",-64);            # align to cache line
+       &and    ("ebp",-64);            # align to cache line
 
        # An OS-agnostic version of __chkstk.
        #
@@ -103,20 +102,28 @@ $frame=32;                                # size of above frame rounded up to 16n
        # be punishable by SEGV. But page walking can do good even on
        # other OSes, because it guarantees that villain thread hits
        # the guard page before it can make damage to innocent one...
-       &mov    ("eax","ebp");
-       &sub    ("eax","esp");
+       &mov    ("eax","esp");
+       &sub    ("eax","ebp");
        &and    ("eax",-4096);
-&set_label("page_walk");
-       &mov    ("edx",&DWP(0,"esp","eax"));
-       &sub    ("eax",4096);
-       &data_byte(0x2e);
-       &jnc    (&label("page_walk"));
+       &mov    ("edx","esp");          # saved stack pointer!
+       &lea    ("esp",&DWP(0,"ebp","eax"));
+       &mov    ("eax",&DWP(0,"esp"));
+       &cmp    ("esp","ebp");
+       &ja     (&label("page_walk"));
+       &jmp    (&label("page_walk_done"));
+
+&set_label("page_walk",16);
+       &lea    ("esp",&DWP(-4096,"esp"));
+       &mov    ("eax",&DWP(0,"esp"));
+       &cmp    ("esp","ebp");
+       &ja     (&label("page_walk"));
+&set_label("page_walk_done");
 
        ################################# load argument block...
        &mov    ("eax",&DWP(0*4,"esi"));# BN_ULONG *rp
        &mov    ("ebx",&DWP(1*4,"esi"));# const BN_ULONG *ap
        &mov    ("ecx",&DWP(2*4,"esi"));# const BN_ULONG *bp
-       &mov    ("edx",&DWP(3*4,"esi"));# const BN_ULONG *np
+       &mov    ("ebp",&DWP(3*4,"esi"));# const BN_ULONG *np
        &mov    ("esi",&DWP(4*4,"esi"));# const BN_ULONG *n0
        #&mov   ("edi",&DWP(5*4,"esi"));# int num
 
@@ -124,11 +131,11 @@ $frame=32;                                # size of above frame rounded up to 16n
        &mov    ($_rp,"eax");           # ... save a copy of argument block
        &mov    ($_ap,"ebx");
        &mov    ($_bp,"ecx");
-       &mov    ($_np,"edx");
+       &mov    ($_np,"ebp");
        &mov    ($_n0,"esi");
        &lea    ($num,&DWP(-3,"edi"));  # num=num-1 to assist modulo-scheduling
        #&mov   ($_num,$num);           # redundant as $num is not reused
-       &mov    ($_sp,"ebp");           # saved stack pointer!
+       &mov    ($_sp,"edx");           # saved stack pointer!
 \f
 if($sse2) {
 $acc0="mm0";   # mmx register bank layout