From: Andy Polyakov Date: Fri, 4 Mar 2016 10:39:11 +0000 (+0100) Subject: bn/asm/x86[_64]-mont*.pl: complement alloca with page-walking. X-Git-Tag: OpenSSL_1_1_0-pre4~335 X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=adc4f1fc25b2cac90076f1e1695b05b7aeeae501 bn/asm/x86[_64]-mont*.pl: complement alloca with page-walking. Some OSes, *cough*-dows, insist on stack being "wired" to physical memory in strictly sequential manner, i.e. if stack allocation spans two pages, then reference to farmost one can 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... Reviewed-by: Rich Salz --- diff --git a/crypto/bn/asm/x86-mont.pl b/crypto/bn/asm/x86-mont.pl index e8f6b05084..89f4de61e8 100755 --- a/crypto/bn/asm/x86-mont.pl +++ b/crypto/bn/asm/x86-mont.pl @@ -85,6 +85,21 @@ $frame=32; # size of above frame rounded up to 16n &and ("esp",-64); # align to cache line + # Some OSes, *cough*-dows, insist on stack being "wired" to + # physical memory in strictly sequential manner, i.e. if stack + # allocation spans two pages, then reference to farmost one can + # 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"); + &and ("eax",-4096); +&set_label("page_walk"); + &mov ("edx",&DWP(0,"esp","eax")); + &sub ("eax",4096); + &data_byte(0x2e); + &jnc (&label("page_walk")); + ################################# load argument block... &mov ("eax",&DWP(0*4,"esi"));# BN_ULONG *rp &mov ("ebx",&DWP(1*4,"esi"));# const BN_ULONG *ap diff --git a/crypto/bn/asm/x86_64-mont.pl b/crypto/bn/asm/x86_64-mont.pl index 29ba1224e3..8fb6c994e1 100755 --- a/crypto/bn/asm/x86_64-mont.pl +++ b/crypto/bn/asm/x86_64-mont.pl @@ -130,6 +130,20 @@ $code.=<<___; mov %r11,8(%rsp,$num,8) # tp[num+1]=%rsp .Lmul_body: + # Some OSes, *cough*-dows, insist on stack being "wired" to + # physical memory in strictly sequential manner, i.e. if stack + # allocation spans two pages, then reference to farmost one can + # 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... + sub %rsp,%r11 + and \$-4096,%r11 +.Lmul_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x66,0x2e # predict non-taken + jnc .Lmul_page_walk + mov $bp,%r12 # reassign $bp ___ $bp="%r12"; @@ -342,6 +356,14 @@ $code.=<<___; mov %r11,8(%rsp,$num,8) # tp[num+1]=%rsp .Lmul4x_body: + sub %rsp,%r11 + and \$-4096,%r11 +.Lmul4x_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lmul4x_page_walk + mov $rp,16(%rsp,$num,8) # tp[num+2]=$rp mov %rdx,%r12 # reassign $bp ___ @@ -795,6 +817,15 @@ bn_sqr8x_mont: sub %r11,%rsp .Lsqr8x_sp_done: and \$-64,%rsp + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lsqr8x_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lsqr8x_page_walk + mov $num,%r10 neg $num @@ -932,8 +963,17 @@ bn_mulx4x_mont: sub $num,%r10 # -$num mov ($n0),$n0 # *n0 lea -72(%rsp,%r10),%rsp # alloca(frame+$num+8) - lea ($bp,$num),%r10 and \$-128,%rsp + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lmulx4x_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x66,0x2e # predict non-taken + jnc .Lmulx4x_page_walk + + lea ($bp,$num),%r10 ############################################################## # Stack layout # +0 num diff --git a/crypto/bn/asm/x86_64-mont5.pl b/crypto/bn/asm/x86_64-mont5.pl index 2e8c9db32c..938e170818 100755 --- a/crypto/bn/asm/x86_64-mont5.pl +++ b/crypto/bn/asm/x86_64-mont5.pl @@ -115,6 +115,20 @@ $code.=<<___; mov %rax,8(%rsp,$num,8) # tp[num+1]=%rsp .Lmul_body: + # Some OSes, *cough*-dows, insist on stack being "wired" to + # physical memory in strictly sequential manner, i.e. if stack + # allocation spans two pages, then reference to farmost one can + # 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... + sub %rsp,%rax + and \$-4096,%rax +.Lmul_page_walk: + mov (%rsp,%rax),%r11 + sub \$4096,%rax + .byte 0x2e # predict non-taken + jnc .Lmul_page_walk + lea 128($bp),%r12 # reassign $bp (+size optimization) ___ $bp="%r12"; @@ -469,6 +483,15 @@ $code.=<<___; sub %r11,%rsp .Lmul4xsp_done: and \$-64,%rsp + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lmul4x_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lmul4x_page_walk + neg $num mov %rax,40(%rsp) @@ -1058,6 +1081,15 @@ $code.=<<___; sub %r11,%rsp .Lpwr_sp_done: and \$-64,%rsp + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lpwr_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lpwr_page_walk + mov $num,%r10 neg $num @@ -2028,7 +2060,16 @@ bn_from_mont8x: sub %r11,%rsp .Lfrom_sp_done: and \$-64,%rsp - mov $num,%r10 + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lfrom_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lfrom_page_walk + + mov $num,%r10 neg $num ############################################################## @@ -2173,6 +2214,15 @@ bn_mulx4x_mont_gather5: sub %r11,%rsp .Lmulx4xsp_done: and \$-64,%rsp # ensure alignment + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lmulx4x_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lmulx4x_page_walk + ############################################################## # Stack layout # +0 -num @@ -2619,6 +2669,15 @@ bn_powerx5: sub %r11,%rsp .Lpwrx_sp_done: and \$-64,%rsp + mov %rax,%r11 + sub %rsp,%r11 + and \$-4096,%r11 +.Lpwrx_page_walk: + mov (%rsp,%r11),%r10 + sub \$4096,%r11 + .byte 0x2e # predict non-taken + jnc .Lpwrx_page_walk + mov $num,%r10 neg $num