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qemu/target/arm/tcg/pauth_helper.c
Peter Maydell 478dccbb99 target/arm: Correct AArch64.S2MinTxSZ 32-bit EL1 input size check 
In check_s2_mmu_setup() we have a check that is attempting to
implement the part of AArch64.S2MinTxSZ that is specific to when EL1
is AArch32:

    if !s1aarch64 then
        // EL1 is AArch32
        min_txsz = Min(min_txsz, 24);

Unfortunately we got this wrong in two ways:

(1) The minimum txsz corresponds to a maximum inputsize, but we got
the sense of the comparison wrong and were faulting for all
inputsizes less than 40 bits

(2) We try to implement this as an extra check that happens after
we've done the same txsz checks we would do for an AArch64 EL1, but
in fact the pseudocode is *loosening* the requirements, so that txsz
values that would fault for an AArch64 EL1 do not fault for AArch32
EL1, because it does Min(old_min, 24), not Max(old_min, 24).

You can see this also in the text of the Arm ARM in table D8-8, which
shows that where the implemented PA size is less than 40 bits an
AArch32 EL1 is still OK with a configured stage2 T0SZ for a 40 bit
IPA, whereas if EL1 is AArch64 then the T0SZ must be big enough to
constrain the IPA to the implemented PA size.

Because of part (2), we can't do this as a separate check, but
have to integrate it into aa64_va_parameters(). Add a new argument
to that function to indicate that EL1 is 32-bit. All the existing
callsites except the one in get_phys_addr_lpae() can pass 'false',
because they are either doing a lookup for a stage 1 regime or
else they don't care about the tsz/tsz_oob fields.

Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1627
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230509092059.3176487-1-peter.maydell@linaro.org
2023-05-12 16:01:25 +01:00

518 lines
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/*
* ARM v8.3-PAuth Operations
*
* Copyright (c) 2019 Linaro, Ltd.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "internals.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#include "exec/helper-proto.h"
#include "tcg/tcg-gvec-desc.h"
#include "qemu/xxhash.h"
static uint64_t pac_cell_shuffle(uint64_t i)
{
uint64_t o = 0;
o |= extract64(i, 52, 4);
o |= extract64(i, 24, 4) << 4;
o |= extract64(i, 44, 4) << 8;
o |= extract64(i, 0, 4) << 12;
o |= extract64(i, 28, 4) << 16;
o |= extract64(i, 48, 4) << 20;
o |= extract64(i, 4, 4) << 24;
o |= extract64(i, 40, 4) << 28;
o |= extract64(i, 32, 4) << 32;
o |= extract64(i, 12, 4) << 36;
o |= extract64(i, 56, 4) << 40;
o |= extract64(i, 20, 4) << 44;
o |= extract64(i, 8, 4) << 48;
o |= extract64(i, 36, 4) << 52;
o |= extract64(i, 16, 4) << 56;
o |= extract64(i, 60, 4) << 60;
return o;
}
static uint64_t pac_cell_inv_shuffle(uint64_t i)
{
uint64_t o = 0;
o |= extract64(i, 12, 4);
o |= extract64(i, 24, 4) << 4;
o |= extract64(i, 48, 4) << 8;
o |= extract64(i, 36, 4) << 12;
o |= extract64(i, 56, 4) << 16;
o |= extract64(i, 44, 4) << 20;
o |= extract64(i, 4, 4) << 24;
o |= extract64(i, 16, 4) << 28;
o |= i & MAKE_64BIT_MASK(32, 4);
o |= extract64(i, 52, 4) << 36;
o |= extract64(i, 28, 4) << 40;
o |= extract64(i, 8, 4) << 44;
o |= extract64(i, 20, 4) << 48;
o |= extract64(i, 0, 4) << 52;
o |= extract64(i, 40, 4) << 56;
o |= i & MAKE_64BIT_MASK(60, 4);
return o;
}
static uint64_t pac_sub(uint64_t i)
{
static const uint8_t sub[16] = {
0xb, 0x6, 0x8, 0xf, 0xc, 0x0, 0x9, 0xe,
0x3, 0x7, 0x4, 0x5, 0xd, 0x2, 0x1, 0xa,
};
uint64_t o = 0;
int b;
for (b = 0; b < 64; b += 4) {
o |= (uint64_t)sub[(i >> b) & 0xf] << b;
}
return o;
}
static uint64_t pac_inv_sub(uint64_t i)
{
static const uint8_t inv_sub[16] = {
0x5, 0xe, 0xd, 0x8, 0xa, 0xb, 0x1, 0x9,
0x2, 0x6, 0xf, 0x0, 0x4, 0xc, 0x7, 0x3,
};
uint64_t o = 0;
int b;
for (b = 0; b < 64; b += 4) {
o |= (uint64_t)inv_sub[(i >> b) & 0xf] << b;
}
return o;
}
static int rot_cell(int cell, int n)
{
/* 4-bit rotate left by n. */
cell |= cell << 4;
return extract32(cell, 4 - n, 4);
}
static uint64_t pac_mult(uint64_t i)
{
uint64_t o = 0;
int b;
for (b = 0; b < 4 * 4; b += 4) {
int i0, i4, i8, ic, t0, t1, t2, t3;
i0 = extract64(i, b, 4);
i4 = extract64(i, b + 4 * 4, 4);
i8 = extract64(i, b + 8 * 4, 4);
ic = extract64(i, b + 12 * 4, 4);
t0 = rot_cell(i8, 1) ^ rot_cell(i4, 2) ^ rot_cell(i0, 1);
t1 = rot_cell(ic, 1) ^ rot_cell(i4, 1) ^ rot_cell(i0, 2);
t2 = rot_cell(ic, 2) ^ rot_cell(i8, 1) ^ rot_cell(i0, 1);
t3 = rot_cell(ic, 1) ^ rot_cell(i8, 2) ^ rot_cell(i4, 1);
o |= (uint64_t)t3 << b;
o |= (uint64_t)t2 << (b + 4 * 4);
o |= (uint64_t)t1 << (b + 8 * 4);
o |= (uint64_t)t0 << (b + 12 * 4);
}
return o;
}
static uint64_t tweak_cell_rot(uint64_t cell)
{
return (cell >> 1) | (((cell ^ (cell >> 1)) & 1) << 3);
}
static uint64_t tweak_shuffle(uint64_t i)
{
uint64_t o = 0;
o |= extract64(i, 16, 4) << 0;
o |= extract64(i, 20, 4) << 4;
o |= tweak_cell_rot(extract64(i, 24, 4)) << 8;
o |= extract64(i, 28, 4) << 12;
o |= tweak_cell_rot(extract64(i, 44, 4)) << 16;
o |= extract64(i, 8, 4) << 20;
o |= extract64(i, 12, 4) << 24;
o |= tweak_cell_rot(extract64(i, 32, 4)) << 28;
o |= extract64(i, 48, 4) << 32;
o |= extract64(i, 52, 4) << 36;
o |= extract64(i, 56, 4) << 40;
o |= tweak_cell_rot(extract64(i, 60, 4)) << 44;
o |= tweak_cell_rot(extract64(i, 0, 4)) << 48;
o |= extract64(i, 4, 4) << 52;
o |= tweak_cell_rot(extract64(i, 40, 4)) << 56;
o |= tweak_cell_rot(extract64(i, 36, 4)) << 60;
return o;
}
static uint64_t tweak_cell_inv_rot(uint64_t cell)
{
return ((cell << 1) & 0xf) | ((cell & 1) ^ (cell >> 3));
}
static uint64_t tweak_inv_shuffle(uint64_t i)
{
uint64_t o = 0;
o |= tweak_cell_inv_rot(extract64(i, 48, 4));
o |= extract64(i, 52, 4) << 4;
o |= extract64(i, 20, 4) << 8;
o |= extract64(i, 24, 4) << 12;
o |= extract64(i, 0, 4) << 16;
o |= extract64(i, 4, 4) << 20;
o |= tweak_cell_inv_rot(extract64(i, 8, 4)) << 24;
o |= extract64(i, 12, 4) << 28;
o |= tweak_cell_inv_rot(extract64(i, 28, 4)) << 32;
o |= tweak_cell_inv_rot(extract64(i, 60, 4)) << 36;
o |= tweak_cell_inv_rot(extract64(i, 56, 4)) << 40;
o |= tweak_cell_inv_rot(extract64(i, 16, 4)) << 44;
o |= extract64(i, 32, 4) << 48;
o |= extract64(i, 36, 4) << 52;
o |= extract64(i, 40, 4) << 56;
o |= tweak_cell_inv_rot(extract64(i, 44, 4)) << 60;
return o;
}
static uint64_t pauth_computepac_architected(uint64_t data, uint64_t modifier,
ARMPACKey key)
{
static const uint64_t RC[5] = {
0x0000000000000000ull,
0x13198A2E03707344ull,
0xA4093822299F31D0ull,
0x082EFA98EC4E6C89ull,
0x452821E638D01377ull,
};
const uint64_t alpha = 0xC0AC29B7C97C50DDull;
/*
* Note that in the ARM pseudocode, key0 contains bits <127:64>
* and key1 contains bits <63:0> of the 128-bit key.
*/
uint64_t key0 = key.hi, key1 = key.lo;
uint64_t workingval, runningmod, roundkey, modk0;
int i;
modk0 = (key0 << 63) | ((key0 >> 1) ^ (key0 >> 63));
runningmod = modifier;
workingval = data ^ key0;
for (i = 0; i <= 4; ++i) {
roundkey = key1 ^ runningmod;
workingval ^= roundkey;
workingval ^= RC[i];
if (i > 0) {
workingval = pac_cell_shuffle(workingval);
workingval = pac_mult(workingval);
}
workingval = pac_sub(workingval);
runningmod = tweak_shuffle(runningmod);
}
roundkey = modk0 ^ runningmod;
workingval ^= roundkey;
workingval = pac_cell_shuffle(workingval);
workingval = pac_mult(workingval);
workingval = pac_sub(workingval);
workingval = pac_cell_shuffle(workingval);
workingval = pac_mult(workingval);
workingval ^= key1;
workingval = pac_cell_inv_shuffle(workingval);
workingval = pac_inv_sub(workingval);
workingval = pac_mult(workingval);
workingval = pac_cell_inv_shuffle(workingval);
workingval ^= key0;
workingval ^= runningmod;
for (i = 0; i <= 4; ++i) {
workingval = pac_inv_sub(workingval);
if (i < 4) {
workingval = pac_mult(workingval);
workingval = pac_cell_inv_shuffle(workingval);
}
runningmod = tweak_inv_shuffle(runningmod);
roundkey = key1 ^ runningmod;
workingval ^= RC[4 - i];
workingval ^= roundkey;
workingval ^= alpha;
}
workingval ^= modk0;
return workingval;
}
static uint64_t pauth_computepac_impdef(uint64_t data, uint64_t modifier,
ARMPACKey key)
{
return qemu_xxhash64_4(data, modifier, key.lo, key.hi);
}
static uint64_t pauth_computepac(CPUARMState *env, uint64_t data,
uint64_t modifier, ARMPACKey key)
{
if (cpu_isar_feature(aa64_pauth_arch, env_archcpu(env))) {
return pauth_computepac_architected(data, modifier, key);
} else {
return pauth_computepac_impdef(data, modifier, key);
}
}
static uint64_t pauth_addpac(CPUARMState *env, uint64_t ptr, uint64_t modifier,
ARMPACKey *key, bool data)
{
ARMMMUIdx mmu_idx = arm_stage1_mmu_idx(env);
ARMVAParameters param = aa64_va_parameters(env, ptr, mmu_idx, data, false);
uint64_t pac, ext_ptr, ext, test;
int bot_bit, top_bit;
/* If tagged pointers are in use, use ptr<55>, otherwise ptr<63>. */
if (param.tbi) {
ext = sextract64(ptr, 55, 1);
} else {
ext = sextract64(ptr, 63, 1);
}
/* Build a pointer with known good extension bits. */
top_bit = 64 - 8 * param.tbi;
bot_bit = 64 - param.tsz;
ext_ptr = deposit64(ptr, bot_bit, top_bit - bot_bit, ext);
pac = pauth_computepac(env, ext_ptr, modifier, *key);
/*
* Check if the ptr has good extension bits and corrupt the
* pointer authentication code if not.
*/
test = sextract64(ptr, bot_bit, top_bit - bot_bit);
if (test != 0 && test != -1) {
/*
* Note that our top_bit is one greater than the pseudocode's
* version, hence "- 2" here.
*/
pac ^= MAKE_64BIT_MASK(top_bit - 2, 1);
}
/*
* Preserve the determination between upper and lower at bit 55,
* and insert pointer authentication code.
*/
if (param.tbi) {
ptr &= ~MAKE_64BIT_MASK(bot_bit, 55 - bot_bit + 1);
pac &= MAKE_64BIT_MASK(bot_bit, 54 - bot_bit + 1);
} else {
ptr &= MAKE_64BIT_MASK(0, bot_bit);
pac &= ~(MAKE_64BIT_MASK(55, 1) | MAKE_64BIT_MASK(0, bot_bit));
}
ext &= MAKE_64BIT_MASK(55, 1);
return pac | ext | ptr;
}
static uint64_t pauth_original_ptr(uint64_t ptr, ARMVAParameters param)
{
uint64_t mask = pauth_ptr_mask(param);
/* Note that bit 55 is used whether or not the regime has 2 ranges. */
if (extract64(ptr, 55, 1)) {
return ptr | mask;
} else {
return ptr & ~mask;
}
}
static uint64_t pauth_auth(CPUARMState *env, uint64_t ptr, uint64_t modifier,
ARMPACKey *key, bool data, int keynumber)
{
ARMMMUIdx mmu_idx = arm_stage1_mmu_idx(env);
ARMVAParameters param = aa64_va_parameters(env, ptr, mmu_idx, data, false);
int bot_bit, top_bit;
uint64_t pac, orig_ptr, test;
orig_ptr = pauth_original_ptr(ptr, param);
pac = pauth_computepac(env, orig_ptr, modifier, *key);
bot_bit = 64 - param.tsz;
top_bit = 64 - 8 * param.tbi;
test = (pac ^ ptr) & ~MAKE_64BIT_MASK(55, 1);
if (unlikely(extract64(test, bot_bit, top_bit - bot_bit))) {
int error_code = (keynumber << 1) | (keynumber ^ 1);
if (param.tbi) {
return deposit64(orig_ptr, 53, 2, error_code);
} else {
return deposit64(orig_ptr, 61, 2, error_code);
}
}
return orig_ptr;
}
static uint64_t pauth_strip(CPUARMState *env, uint64_t ptr, bool data)
{
ARMMMUIdx mmu_idx = arm_stage1_mmu_idx(env);
ARMVAParameters param = aa64_va_parameters(env, ptr, mmu_idx, data, false);
return pauth_original_ptr(ptr, param);
}
static G_NORETURN
void pauth_trap(CPUARMState *env, int target_el, uintptr_t ra)
{
raise_exception_ra(env, EXCP_UDEF, syn_pactrap(), target_el, ra);
}
static void pauth_check_trap(CPUARMState *env, int el, uintptr_t ra)
{
if (el < 2 && arm_is_el2_enabled(env)) {
uint64_t hcr = arm_hcr_el2_eff(env);
bool trap = !(hcr & HCR_API);
if (el == 0) {
/* Trap only applies to EL1&0 regime. */
trap &= (hcr & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE);
}
/* FIXME: ARMv8.3-NV: HCR_NV trap takes precedence for ERETA[AB]. */
if (trap) {
pauth_trap(env, 2, ra);
}
}
if (el < 3 && arm_feature(env, ARM_FEATURE_EL3)) {
if (!(env->cp15.scr_el3 & SCR_API)) {
pauth_trap(env, 3, ra);
}
}
}
static bool pauth_key_enabled(CPUARMState *env, int el, uint32_t bit)
{
return (arm_sctlr(env, el) & bit) != 0;
}
uint64_t HELPER(pacia)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnIA)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_addpac(env, x, y, &env->keys.apia, false);
}
uint64_t HELPER(pacib)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnIB)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_addpac(env, x, y, &env->keys.apib, false);
}
uint64_t HELPER(pacda)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnDA)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_addpac(env, x, y, &env->keys.apda, true);
}
uint64_t HELPER(pacdb)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnDB)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_addpac(env, x, y, &env->keys.apdb, true);
}
uint64_t HELPER(pacga)(CPUARMState *env, uint64_t x, uint64_t y)
{
uint64_t pac;
pauth_check_trap(env, arm_current_el(env), GETPC());
pac = pauth_computepac(env, x, y, env->keys.apga);
return pac & 0xffffffff00000000ull;
}
uint64_t HELPER(autia)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnIA)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_auth(env, x, y, &env->keys.apia, false, 0);
}
uint64_t HELPER(autib)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnIB)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_auth(env, x, y, &env->keys.apib, false, 1);
}
uint64_t HELPER(autda)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnDA)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_auth(env, x, y, &env->keys.apda, true, 0);
}
uint64_t HELPER(autdb)(CPUARMState *env, uint64_t x, uint64_t y)
{
int el = arm_current_el(env);
if (!pauth_key_enabled(env, el, SCTLR_EnDB)) {
return x;
}
pauth_check_trap(env, el, GETPC());
return pauth_auth(env, x, y, &env->keys.apdb, true, 1);
}
uint64_t HELPER(xpaci)(CPUARMState *env, uint64_t a)
{
return pauth_strip(env, a, false);
}
uint64_t HELPER(xpacd)(CPUARMState *env, uint64_t a)
{
return pauth_strip(env, a, true);
}
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