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| author | Richard Henderson <richard.henderson@linaro.org> | 2020-08-03 17:55:03 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2020-08-03 17:55:03 +0100 |
| commit | 8796fe40dd30cd9ffd3c958906471715c923b341 (patch) | |
| tree | b46f26f03cfe41809b07f5675f592bc44a9fb682 /target/arm | |
| parent | fc6bb6e67e2f2b81de765a1c1ad5956de625ab19 (diff) | |
| download | qemu-8796fe40dd30cd9ffd3c958906471715c923b341.zip | |
target/arm: Fix AddPAC error indication
The definition of top_bit used in this function is one higher
than that used in the Arm ARM psuedo-code, which put the error
indication at top_bit - 1 at the wrong place, which meant that
it wasn't visible to Auth.
Fixing the definition of top_bit requires more changes, because
its most common use is for the count of bits in top_bit:bot_bit,
which would then need to be computed as top_bit - bot_bit + 1.
For now, prefer the minimal fix to the error indication alone.
Fixes: 63ff0ca94cb
Reported-by: Derrick McKee <derrick.mckee@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200728195706.11087-1-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: added comment about the divergence from the pseudocode]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'target/arm')
| -rw-r--r-- | target/arm/pauth_helper.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c index b909630317..6dbab03768 100644 --- a/target/arm/pauth_helper.c +++ b/target/arm/pauth_helper.c @@ -300,7 +300,11 @@ static uint64_t pauth_addpac(CPUARMState *env, uint64_t ptr, uint64_t modifier, */ test = sextract64(ptr, bot_bit, top_bit - bot_bit); if (test != 0 && test != -1) { - pac ^= MAKE_64BIT_MASK(top_bit - 1, 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); } /* |