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Revise OPENSSL_ia32cap_P strategy to avoid TEXTRELs.

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OPENSSL_ia32cap_addr avoids any relocations within the module, at the
cost of a runtime TEXTREL, which causes problems in some cases.
(Notably, if someone links us into a binary which uses the GCC "ifunc"
attribute, the loader crashes.)

We add a OPENSSL_ia32cap_addr_delta symbol (which is reachable
relocation-free from the module) stores the difference between
OPENSSL_ia32cap_P and its own address.  Next, reference
OPENSSL_ia32cap_P in code as usual, but always doing LEAQ (or the
equivalent GOTPCREL MOVQ) into a register first. This pattern we can
then transform into a LEAQ and ADDQ on OPENSSL_ia32cap_addr_delta.

ADDQ modifies the FLAGS register, so this is only a safe transformation
if we safe and restore flags first. That, in turn, is only a safe
transformation if code always uses %rsp as a stack pointer (specifically
everything below the stack must be fair game for scribbling over). Linux
delivers signals on %rsp, so this should already be an ABI requirement.
Further, we must clear the red zone (using LEAQ to avoid touching FLAGS)
which signal handlers may not scribble over.

This also fixes the GOTTPOFF logic to clear the red zone.

Change-Id: I4ca6133ab936d5a13d5c8ef265a12ab6bd0073c9
Reviewed-on: https://boringssl-review.googlesource.com/15545
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
This commit is contained in:
David Benjamin 2017-04-25 18:32:32 -04:00 committed by CQ bot account: commit-bot@chromium.org
parent 075875fbf6
commit def85b403d
7 changed files with 51 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
crypto/crypto.c
View File

@ -58,9 +58,6 @@
* initialising it to zero, it becomes a "data symbol", which isn't so
* affected. */
uint32_t OPENSSL_ia32cap_P[4] = {0};
#if !defined(BORINGSSL_FIPS)
uint32_t *OPENSSL_ia32cap_addr = OPENSSL_ia32cap_P;
#endif
#elif defined(OPENSSL_PPC64LE)

4
crypto/fipsmodule/aes/asm/aes-x86_64.pl
View File

@ -1642,7 +1642,7 @@ $code.=<<___;
.align 16
.globl asm_AES_cbc_encrypt
.type asm_AES_cbc_encrypt,\@function,6
.extern OPENSSL_ia32cap_addr
.extern OPENSSL_ia32cap_P
.hidden asm_AES_cbc_encrypt
asm_AES_cbc_encrypt:
cmp \$0,%rdx # check length
@ -1664,7 +1664,7 @@ asm_AES_cbc_encrypt:
cmp \$0,%r9
cmoveq %r10,$sbox
mov OPENSSL_ia32cap_addr(%rip),%r10
leaq OPENSSL_ia32cap_P(%rip),%r10
mov (%r10), %r10d
cmp \$$speed_limit,%rdx
jb .Lcbc_slow_prologue

8
crypto/fipsmodule/aes/asm/aesni-x86_64.pl
View File

@ -209,7 +209,7 @@ $movkey = $PREFIX eq "aesni" ? "movups" : "movups";
("%rdi","%rsi","%rdx","%rcx"); # Unix order
$code=".text\n";
$code.=".extern OPENSSL_ia32cap_addr\n";
$code.=".extern OPENSSL_ia32cap_P\n";
$rounds="%eax"; # input to and changed by aesni_[en|de]cryptN !!!
# this is natural Unix argument order for public $PREFIX_[ecb|cbc]_encrypt ...
@ -1271,7 +1271,7 @@ $code.=<<___;
lea 7($ctr),%r9
mov %r10d,0x60+12(%rsp)
bswap %r9d
movq OPENSSL_ia32cap_addr(%rip),%r10
leaq OPENSSL_ia32cap_P(%rip),%r10
mov 4(%r10),%r10d
xor $key0,%r9d
and \$`1<<26|1<<22`,%r10d # isolate XSAVE+MOVBE
@ -3772,7 +3772,7 @@ $code.=<<___;
movdqa $inout3,$in3
movdqu 0x50($inp),$inout5
movdqa $inout4,$in4
movq OPENSSL_ia32cap_addr(%rip),%r9
leaq OPENSSL_ia32cap_P(%rip),%r9
mov 4(%r9),%r9d
cmp \$0x70,$len
jbe .Lcbc_dec_six_or_seven
@ -4278,7 +4278,7 @@ __aesni_set_encrypt_key:
movups ($inp),%xmm0 # pull first 128 bits of *userKey
xorps %xmm4,%xmm4 # low dword of xmm4 is assumed 0
movq OPENSSL_ia32cap_addr(%rip),%r10
leaq OPENSSL_ia32cap_P(%rip),%r10
movl 4(%r10),%r10d
and \$`1<<28|1<<11`,%r10d # AVX and XOP bits
lea 16($key),%rax # %rax is used as modifiable copy of $key

65
crypto/fipsmodule/delocate.go
View File

@ -121,16 +121,6 @@ func definedSymbols(lines []string) map[string]bool {
return symbols
}
func referencesIA32CapDirectly(line string) bool {
const symbol = "OPENSSL_ia32cap_P"
i := strings.Index(line, symbol)
if i < 0 {
return false
}
i += len(symbol)
return i == len(line) || line[i] == '+' || line[i] == '(' || line[i] == '@'
}
// threadLocalOffsetFunc describes a function that fetches the offset to symbol
// in the thread-local space and writes it to the given target register.
type threadLocalOffsetFunc struct {
@ -231,9 +221,9 @@ func transform(lines []string, symbols map[string]bool) (ret []string) {
// redirector function for that symbol.
redirectors := make(map[string]string)
// ia32capAddrNeeded is true iff OPENSSL_ia32cap_addr has been
// referenced and thus needs to be emitted outside the module.
ia32capAddrNeeded := false
// ia32capAddrDeltaNeeded is true iff OPENSSL_ia32cap_addr_delta has
// been referenced and thus needs to be emitted outside the module.
ia32capAddrDeltaNeeded := false
// ia32capGetNeeded is true iff OPENSSL_ia32cap_get has been referenced
// and thus needs to be emitted outside the module.
@ -258,14 +248,6 @@ func transform(lines []string, symbols map[string]bool) (ret []string) {
break
}
if referencesIA32CapDirectly(line) {
panic("reference to OPENSSL_ia32cap_P needs to be changed to indirect via OPENSSL_ia32cap_addr")
}
if strings.Contains(line, "OPENSSL_ia32cap_addr(%rip)") {
ia32capAddrNeeded = true
}
if strings.Contains(line, "OPENSSL_ia32cap_get@PLT") {
ia32capGetNeeded = true
}
@ -326,7 +308,9 @@ func transform(lines []string, symbols map[string]bool) (ret []string) {
symbol := strings.SplitN(args[0], "@", 2)[0]
functionName := fmt.Sprintf("BORINGSSL_bcm_tpoff_to_%s_for_%s", targetRegister, symbol)
threadLocalOffsets[functionName] = threadLocalOffsetFunc{target: targetRegister, symbol: symbol}
ret = append(ret, "leaq -128(%rsp), %rsp") // Clear the red zone.
ret = append(ret, "\tcallq "+functionName+"\n")
ret = append(ret, "leaq 128(%rsp), %rsp")
continue
}
@ -351,6 +335,35 @@ func transform(lines []string, symbols map[string]bool) (ret []string) {
// referencing the symbol directly,
// needs to be transformed into an LEA.
line = strings.Replace(line, "movq", "leaq", 1)
instr = "leaq"
}
if target == "OPENSSL_ia32cap_P" {
if instr != "leaq" {
panic("reference to OPENSSL_ia32cap_P needs to be changed to go through leaq or GOTPCREL")
}
if args[1][0] != '%' {
panic("reference to OPENSSL_ia32cap_P must target a register.")
}
// We assume pushfq is safe, after
// clearing the red zone, because any
// signals will be delivered using
// %rsp. Thus perlasm and
// compiler-generated code must not use
// %rsp as a general-purpose register.
//
// TODO(davidben): This messes up CFI
// for a small window if %rsp is the CFI
// register.
ia32capAddrDeltaNeeded = true
ret = append(ret, "leaq -128(%rsp), %rsp") // Clear the red zone.
ret = append(ret, "pushfq")
ret = append(ret, fmt.Sprintf("leaq OPENSSL_ia32cap_addr_delta(%%rip), %s", args[1]))
ret = append(ret, fmt.Sprintf("addq OPENSSL_ia32cap_addr_delta(%%rip), %s", args[1]))
ret = append(ret, "popfq")
ret = append(ret, "leaq 128(%rsp), %rsp")
continue
}
}
@ -468,12 +481,12 @@ func transform(lines []string, symbols map[string]bool) (ret []string) {
}
// Emit an indirect reference to OPENSSL_ia32cap_P.
if ia32capAddrNeeded {
if ia32capAddrDeltaNeeded {
ret = append(ret, ".extern OPENSSL_ia32cap_P")
ret = append(ret, ".type OPENSSL_ia32cap_addr,@object")
ret = append(ret, ".size OPENSSL_ia32cap_addr,8")
ret = append(ret, "OPENSSL_ia32cap_addr:")
ret = append(ret, "\t.quad OPENSSL_ia32cap_P")
ret = append(ret, ".type OPENSSL_ia32cap_addr_delta,@object")
ret = append(ret, ".size OPENSSL_ia32cap_addr_delta,8")
ret = append(ret, "OPENSSL_ia32cap_addr_delta:")
ret = append(ret, "\t.quad OPENSSL_ia32cap_P-OPENSSL_ia32cap_addr_delta")
}
// Emit accessors for thread-local offsets.

4
crypto/fipsmodule/modes/asm/ghash-x86_64.pl
View File

@ -212,7 +212,7 @@ ___
$code=<<___;
.text
.extern OPENSSL_ia32cap_addr
.extern OPENSSL_ia32cap_P
.globl gcm_gmult_4bit
.type gcm_gmult_4bit,\@function,2
@ -644,7 +644,7 @@ if ($do4xaggr) {
my ($Xl,$Xm,$Xh,$Hkey3,$Hkey4)=map("%xmm$_",(11..15));
$code.=<<___;
mov OPENSSL_ia32cap_addr(%rip),%rax
leaq OPENSSL_ia32cap_P(%rip),%rax
mov 4(%rax),%eax
cmp \$0x30,$len
jb .Lskip4x

5
crypto/fipsmodule/sha/asm/sha1-x86_64.pl
View File

@ -236,14 +236,13 @@ push(@xi,shift(@xi));
$code.=<<___;
.text
.extern OPENSSL_ia32cap_addr
.extern OPENSSL_ia32cap_P
.globl sha1_block_data_order
.type sha1_block_data_order,\@function,3
.align 16
sha1_block_data_order:
lea OPENSSL_ia32cap_addr(%rip),%r10
mov (%r10),%r10
leaq OPENSSL_ia32cap_P(%rip),%r10
mov 0(%r10),%r9d
mov 4(%r10),%r8d
mov 8(%r10),%r10d

5
crypto/fipsmodule/sha/asm/sha512-x86_64.pl
View File

@ -249,15 +249,14 @@ ___
$code=<<___;
.text
.extern OPENSSL_ia32cap_addr
.extern OPENSSL_ia32cap_P
.globl $func
.type $func,\@function,3
.align 16
$func:
___
$code.=<<___ if ($SZ==4 || $avx);
lea OPENSSL_ia32cap_addr(%rip),%r11
mov (%r11),%r11
leaq OPENSSL_ia32cap_P(%rip),%r11
mov 0(%r11),%r9d
mov 4(%r11),%r10d
mov 8(%r11),%r11d