OpenBSD/macppc can enforce xonly on the PowerPC G5. libcrypto linked
with cc -Wl,--execute-only will SIGSEGV as the PowerPC asm of sha256
tries to read a table from text. The fix is to move the table to
rodata. To find the table, I would do
bcl 20, 31, 1f
1: mflr %r7
addis %r7, %r7, .Ltable-1b@ha
addi %r7, %r7, .Ltable-1b@l
This diff does so in perlasm syntax. The literal "@ha" and "@l" in
this diff are for an ELF platform (like OpenBSD) and might break the
build for AIX or Mac OS, but I suspect that nobody builds this asm
for those platforms. (PowerPC Mac OS is long obsolete, ended at
Mac OS X 10.5.8.) If someone wants to try the PowerPC asm on a
not-ELF platform, please tell me.
aes-ppc.pl would have the same problem, but we don't use aes-ppc.pl,
so I provide no fix. ports/security/openssl/{1.0.2,1.1,3.0} has
copies of aes-ppc.pl and sha512-ppc.pl with the same problem, but
doesn't enable them on OpenBSD, so I don't plan to edit them.
sha512-ppc.pl can emit code for sha256 or sha512, but we only use it
for sha256. The code uses simple ops (add, subtract, bit logic,
bit rotation), nothing more fancy. I don't know why it runs faster
than the (not asm) sha256 in ports/security/openssl.
ok for this diff in src/lib/libcrypto?
--George
Index: sha/asm/sha512-ppc.pl
===================================================================
RCS file: /cvs/src/lib/libcrypto/sha/asm/sha512-ppc.pl,v
retrieving revision 1.3
diff -u -p -r1.3 sha512-ppc.pl
--- sha/asm/sha512-ppc.pl 14 Nov 2015 14:53:13 -0000 1.3
+++ sha/asm/sha512-ppc.pl 31 Jan 2023 22:03:47 -0000
@@ -220,8 +220,11 @@ $func:
$LD $G,`6*$SZ`($ctx)
$LD $H,`7*$SZ`($ctx)
- bl LPICmeup
-LPICedup:
+ bcl 20,31,Lpc
+Lpc:
+ mflr $Tbl
+ addis $Tbl,$Tbl,Ltable-Lpc\@ha
+ addi $Tbl,$Tbl,Ltable-Lpc\@l
andi. r0,$inp,3
bne Lunaligned
Laligned:
@@ -377,22 +380,8 @@ $code.=<<___;
blr
.long 0
.byte 0,12,0x14,0,0,0,0,0
-___
-
-# Ugly hack here, because PPC assembler syntax seem to vary too
-# much from platforms to platform...
-$code.=<<___;
-.align 6
-LPICmeup:
- mflr r0
- bcl 20,31,\$+4
- mflr $Tbl ; vvvvvv "distance" between . and 1st data entry
- addi $Tbl,$Tbl,`64-8`
- mtlr r0
- blr
- .long 0
- .byte 0,12,0x14,0,0,0,0,0
- .space `64-9*4`
+ .rodata
+Ltable:
___
$code.=<<___ if ($SZ==8);
.long 0x428a2f98,0xd728ae22,0x71374491,0x23ef65cd
