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    Subject[PATCH 5.15 643/779] s390/maccess: rework absolute lowcore accessors
    Date
    From: Alexander Gordeev <agordeev@linux.ibm.com>

    [ Upstream commit ed0192bc644f3553d64a5cb461bdd0b1fbae3fdf ]

    Macro mem_assign_absolute() is able to access the whole memory, but
    is only used and makes sense when updating the absolute lowcore.
    Instead, introduce get_abs_lowcore() and put_abs_lowcore() macros
    that limit access to absolute lowcore addresses only.

    Suggested-by: Heiko Carstens <hca@linux.ibm.com>
    Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
    Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
    Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/s390/include/asm/processor.h | 17 ++++++++++++-----
    arch/s390/kernel/ipl.c | 4 ++--
    arch/s390/kernel/machine_kexec.c | 2 +-
    arch/s390/kernel/os_info.c | 2 +-
    arch/s390/kernel/setup.c | 19 ++++++++++---------
    arch/s390/kernel/smp.c | 12 ++++++------
    6 files changed, 32 insertions(+), 24 deletions(-)

    diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
    index e9db8efd50f2..d7ca76bb2720 100644
    --- a/arch/s390/include/asm/processor.h
    +++ b/arch/s390/include/asm/processor.h
    @@ -321,11 +321,18 @@ extern void (*s390_base_pgm_handler_fn)(void);
    extern int memcpy_real(void *, unsigned long, size_t);
    extern void memcpy_absolute(void *, void *, size_t);

    -#define mem_assign_absolute(dest, val) do { \
    - __typeof__(dest) __tmp = (val); \
    - \
    - BUILD_BUG_ON(sizeof(__tmp) != sizeof(val)); \
    - memcpy_absolute(&(dest), &__tmp, sizeof(__tmp)); \
    +#define put_abs_lowcore(member, x) do { \
    + unsigned long __abs_address = offsetof(struct lowcore, member); \
    + __typeof__(((struct lowcore *)0)->member) __tmp = (x); \
    + \
    + memcpy_absolute(__va(__abs_address), &__tmp, sizeof(__tmp)); \
    +} while (0)
    +
    +#define get_abs_lowcore(x, member) do { \
    + unsigned long __abs_address = offsetof(struct lowcore, member); \
    + __typeof__(((struct lowcore *)0)->member) *__ptr = &(x); \
    + \
    + memcpy_absolute(__ptr, __va(__abs_address), sizeof(*__ptr)); \
    } while (0)

    extern int s390_isolate_bp(void);
    diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
    index 5ad1dde23dc5..ba2988783d66 100644
    --- a/arch/s390/kernel/ipl.c
    +++ b/arch/s390/kernel/ipl.c
    @@ -1646,8 +1646,8 @@ static void dump_reipl_run(struct shutdown_trigger *trigger)

    csum = (__force unsigned int)
    csum_partial(reipl_block_actual, reipl_block_actual->hdr.len, 0);
    - mem_assign_absolute(S390_lowcore.ipib, ipib);
    - mem_assign_absolute(S390_lowcore.ipib_checksum, csum);
    + put_abs_lowcore(ipib, ipib);
    + put_abs_lowcore(ipib_checksum, csum);
    dump_run(trigger);
    }

    diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
    index 0505e55a6297..4b95684fbe46 100644
    --- a/arch/s390/kernel/machine_kexec.c
    +++ b/arch/s390/kernel/machine_kexec.c
    @@ -227,7 +227,7 @@ void arch_crash_save_vmcoreinfo(void)
    vmcoreinfo_append_str("SAMODE31=%lx\n", __samode31);
    vmcoreinfo_append_str("EAMODE31=%lx\n", __eamode31);
    vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
    - mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note());
    + put_abs_lowcore(vmcore_info, paddr_vmcoreinfo_note());
    }

    void machine_shutdown(void)
    diff --git a/arch/s390/kernel/os_info.c b/arch/s390/kernel/os_info.c
    index 6b5b64e67eee..1acc2e05d70f 100644
    --- a/arch/s390/kernel/os_info.c
    +++ b/arch/s390/kernel/os_info.c
    @@ -63,7 +63,7 @@ void __init os_info_init(void)
    os_info.version_minor = OS_INFO_VERSION_MINOR;
    os_info.magic = OS_INFO_MAGIC;
    os_info.csum = os_info_csum(&os_info);
    - mem_assign_absolute(S390_lowcore.os_info, __pa(ptr));
    + put_abs_lowcore(os_info, __pa(ptr));
    }

    #ifdef CONFIG_CRASH_DUMP
    diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
    index 36c1f31dfd66..6b1a8697fae8 100644
    --- a/arch/s390/kernel/setup.c
    +++ b/arch/s390/kernel/setup.c
    @@ -479,11 +479,11 @@ static void __init setup_lowcore_dat_off(void)
    lc->mcck_stack = mcck_stack + STACK_INIT_OFFSET;

    /* Setup absolute zero lowcore */
    - mem_assign_absolute(S390_lowcore.restart_stack, lc->restart_stack);
    - mem_assign_absolute(S390_lowcore.restart_fn, lc->restart_fn);
    - mem_assign_absolute(S390_lowcore.restart_data, lc->restart_data);
    - mem_assign_absolute(S390_lowcore.restart_source, lc->restart_source);
    - mem_assign_absolute(S390_lowcore.restart_psw, lc->restart_psw);
    + put_abs_lowcore(restart_stack, lc->restart_stack);
    + put_abs_lowcore(restart_fn, lc->restart_fn);
    + put_abs_lowcore(restart_data, lc->restart_data);
    + put_abs_lowcore(restart_source, lc->restart_source);
    + put_abs_lowcore(restart_psw, lc->restart_psw);

    lc->spinlock_lockval = arch_spin_lockval(0);
    lc->spinlock_index = 0;
    @@ -500,6 +500,7 @@ static void __init setup_lowcore_dat_off(void)
    static void __init setup_lowcore_dat_on(void)
    {
    struct lowcore *lc = lowcore_ptr[0];
    + int cr;

    __ctl_clear_bit(0, 28);
    S390_lowcore.external_new_psw.mask |= PSW_MASK_DAT;
    @@ -508,10 +509,10 @@ static void __init setup_lowcore_dat_on(void)
    S390_lowcore.io_new_psw.mask |= PSW_MASK_DAT;
    __ctl_store(S390_lowcore.cregs_save_area, 0, 15);
    __ctl_set_bit(0, 28);
    - mem_assign_absolute(S390_lowcore.restart_flags, RESTART_FLAG_CTLREGS);
    - mem_assign_absolute(S390_lowcore.program_new_psw, lc->program_new_psw);
    - memcpy_absolute(&S390_lowcore.cregs_save_area, lc->cregs_save_area,
    - sizeof(S390_lowcore.cregs_save_area));
    + put_abs_lowcore(restart_flags, RESTART_FLAG_CTLREGS);
    + put_abs_lowcore(program_new_psw, lc->program_new_psw);
    + for (cr = 0; cr < ARRAY_SIZE(lc->cregs_save_area); cr++)
    + put_abs_lowcore(cregs_save_area[cr], lc->cregs_save_area[cr]);
    }

    static struct resource code_resource = {
    diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
    index 7bbcb5b8d3f6..35af70ed58fc 100644
    --- a/arch/s390/kernel/smp.c
    +++ b/arch/s390/kernel/smp.c
    @@ -334,10 +334,10 @@ static void pcpu_delegate(struct pcpu *pcpu,
    lc->restart_data = (unsigned long)data;
    lc->restart_source = source_cpu;
    } else {
    - mem_assign_absolute(lc->restart_stack, stack);
    - mem_assign_absolute(lc->restart_fn, (unsigned long)func);
    - mem_assign_absolute(lc->restart_data, (unsigned long)data);
    - mem_assign_absolute(lc->restart_source, source_cpu);
    + put_abs_lowcore(restart_stack, stack);
    + put_abs_lowcore(restart_fn, (unsigned long)func);
    + put_abs_lowcore(restart_data, (unsigned long)data);
    + put_abs_lowcore(restart_source, source_cpu);
    }
    __bpon();
    asm volatile(
    @@ -593,9 +593,9 @@ void smp_ctl_set_clear_bit(int cr, int bit, bool set)
    parms.andval = ~(1UL << bit);
    }
    spin_lock(&ctl_lock);
    - memcpy_absolute(&ctlreg, &S390_lowcore.cregs_save_area[cr], sizeof(ctlreg));
    + get_abs_lowcore(ctlreg, cregs_save_area[cr]);
    ctlreg = (ctlreg & parms.andval) | parms.orval;
    - memcpy_absolute(&S390_lowcore.cregs_save_area[cr], &ctlreg, sizeof(ctlreg));
    + put_abs_lowcore(cregs_save_area[cr], ctlreg);
    spin_unlock(&ctl_lock);
    on_each_cpu(smp_ctl_bit_callback, &parms, 1);
    }
    --
    2.35.1


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