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target/arm: Implement an IMPDEF pauth algorithm

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Without hardware acceleration, a cryptographically strong
algorithm is too expensive for pauth_computepac.

Even with hardware accel, we are not currently expecting
to link the linux-user binaries to any crypto libraries,
and doing so would generally make the --static build fail.

So choose XXH64 as a reasonably quick and decent hash.

Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210111235740.462469-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2021-01-11 13:57:38 -10:00 • committed by Peter Maydell
parent f1fcb6851a
commit 283fc52ade
3 changed files with 131 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

27
target/arm/pauth_helper.c
View file

@ -24,6 +24,7 @@
#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)
@ -207,8 +208,8 @@ static uint64_t tweak_inv_shuffle(uint64_t i)
return o;
}
static uint64_t pauth_computepac(uint64_t data, uint64_t modifier,
ARMPACKey key)
static uint64_t pauth_computepac_architected(uint64_t data, uint64_t modifier,
ARMPACKey key)
{
static const uint64_t RC[5] = {
0x0000000000000000ull,
@ -272,6 +273,22 @@ static uint64_t pauth_computepac(uint64_t data, uint64_t modifier,
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)
{
@ -292,7 +309,7 @@ static uint64_t pauth_addpac(CPUARMState *env, uint64_t ptr, uint64_t modifier,
bot_bit = 64 - param.tsz;
ext_ptr = deposit64(ptr, bot_bit, top_bit - bot_bit, ext);
pac = pauth_computepac(ext_ptr, modifier, *key);
pac = pauth_computepac(env, ext_ptr, modifier, *key);
/*
* Check if the ptr has good extension bits and corrupt the
@ -341,7 +358,7 @@ static uint64_t pauth_auth(CPUARMState *env, uint64_t ptr, uint64_t modifier,
uint64_t pac, orig_ptr, test;
orig_ptr = pauth_original_ptr(ptr, param);
pac = pauth_computepac(orig_ptr, modifier, *key);
pac = pauth_computepac(env, orig_ptr, modifier, *key);
bot_bit = 64 - param.tsz;
top_bit = 64 - 8 * param.tbi;
@ -442,7 +459,7 @@ 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(x, y, env->keys.apga);
pac = pauth_computepac(env, x, y, env->keys.apga);
return pac & 0xffffffff00000000ull;
}