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    Subject[PATCH 5.15 819/917] arm64: arm64_ftr_reg->name may not be a human-readable string
    Date
    From: Reiji Watanabe <reijiw@google.com>

    [ Upstream commit 9dc232a8ab18bb20f1dcb03c8e049e3607f3ed15 ]

    The id argument of ARM64_FTR_REG_OVERRIDE() is used for two purposes:
    one as the system register encoding (used for the sys_id field of
    __ftr_reg_entry), and the other as the register name (stringified
    and used for the name field of arm64_ftr_reg), which is debug
    information. The id argument is supposed to be a macro that
    indicates an encoding of the register (eg. SYS_ID_AA64PFR0_EL1, etc).

    ARM64_FTR_REG(), which also has the same id argument,
    uses ARM64_FTR_REG_OVERRIDE() and passes the id to the macro.
    Since the id argument is completely macro-expanded before it is
    substituted into a macro body of ARM64_FTR_REG_OVERRIDE(),
    the stringified id in the body of ARM64_FTR_REG_OVERRIDE is not
    a human-readable register name, but a string of numeric bitwise
    operations.

    Fix this so that human-readable register names are available as
    debug information.

    Fixes: 8f266a5d878a ("arm64: cpufeature: Add global feature override facility")
    Signed-off-by: Reiji Watanabe <reijiw@google.com>
    Reviewed-by: Oliver Upton <oupton@google.com>
    Acked-by: Marc Zyngier <maz@kernel.org>
    Link: https://lore.kernel.org/r/20211101045421.2215822-1-reijiw@google.com
    Signed-off-by: Will Deacon <will@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm64/kernel/cpufeature.c | 10 +++++++---
    1 file changed, 7 insertions(+), 3 deletions(-)

    diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
    index 6ec7036ef7e18..7553c98f379fc 100644
    --- a/arch/arm64/kernel/cpufeature.c
    +++ b/arch/arm64/kernel/cpufeature.c
    @@ -573,15 +573,19 @@ static const struct arm64_ftr_bits ftr_raz[] = {
    ARM64_FTR_END,
    };

    -#define ARM64_FTR_REG_OVERRIDE(id, table, ovr) { \
    +#define __ARM64_FTR_REG_OVERRIDE(id_str, id, table, ovr) { \
    .sys_id = id, \
    .reg = &(struct arm64_ftr_reg){ \
    - .name = #id, \
    + .name = id_str, \
    .override = (ovr), \
    .ftr_bits = &((table)[0]), \
    }}

    -#define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, &no_override)
    +#define ARM64_FTR_REG_OVERRIDE(id, table, ovr) \
    + __ARM64_FTR_REG_OVERRIDE(#id, id, table, ovr)
    +
    +#define ARM64_FTR_REG(id, table) \
    + __ARM64_FTR_REG_OVERRIDE(#id, id, table, &no_override)

    struct arm64_ftr_override __ro_after_init id_aa64mmfr1_override;
    struct arm64_ftr_override __ro_after_init id_aa64pfr1_override;
    --
    2.33.0


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