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From: K Prateek Nayak <kprateek.nayak@amd.com>
To: Guo Ren <guoren@kernel.org>
Cc: "Thomas Gleixner" <tglx@kernel.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
	"Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Samuel Holland" <samuel.holland@sifive.com>,
	"David Laight" <david.laight.linux@gmail.com>,
	"Darren Hart" <dvhart@infradead.org>,
	"Davidlohr Bueso" <dave@stgolabs.net>,
	"André Almeida" <andrealmeid@igalia.com>,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-s390@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Charlie Jenkins" <charlie@rivosinc.com>,
	"Charles Mirabile" <cmirabil@redhat.com>
Subject: Re: [PATCH v3 4/7] riscv/runtime-const: Introduce runtime_const_mask_32()
Date: Fri, 3 Apr 2026 16:05:17 +0530	[thread overview]
Message-ID: <f47a0887-9890-44f3-8532-47b6afefe09d@amd.com> (raw)
In-Reply-To: <CAJF2gTSDg7JWHGS5E_OQWibFRTrY5bUuoOntmVE-MCt+FawLZw@mail.gmail.com>

Hello Guo,

On 4/3/2026 3:12 PM, Guo Ren wrote:
>> diff --git a/arch/riscv/include/asm/runtime-const.h b/arch/riscv/include/asm/runtime-const.h
>> index d766e2b9e6df..85efba8ecf12 100644
>> --- a/arch/riscv/include/asm/runtime-const.h
>> +++ b/arch/riscv/include/asm/runtime-const.h
>> @@ -153,6 +153,22 @@
>>         __ret;                                                  \
>>  })
>>
>> +#define runtime_const_mask_32(val, sym)                                \
>> +({                                                             \
>> +       u32 __mask;                                             \
>> +       asm_inline(".option push\n\t"                           \
>> +               ".option norvc\n\t"                             \
>> +               "1:\t"                                          \
>> +               "lui    %[__mask],0x89abd\n\t"                  \
>> +               "addi   %[__mask],%[__mask],-0x211\n\t"         \
> Ref include/uapi/linux/reboot.h:
> #define LINUX_REBOOT_CMD_CAD_ON 0x89ABCDEF
> 
> #define RUNTIME_MAGIC 0x89ABCDEF
> 
> "lui %[__mask], %%hi(RUNTIME_MAGIC)\n\t"
> "addi %[__mask], %[__mask], %%lo(RUNTIME_MAGIC)\n\t"

Ack! I'll clean it up in the next version while also fixing the
stuff that Sashiko reported.

Thanks a ton for taking a look at the series.

> 
> 
>> +               ".option pop\n\t"                               \
>> +               ".pushsection runtime_mask_" #sym ",\"a\"\n\t"  \
>> +               ".long 1b - .\n\t"                              \
>> +               ".popsection"                                   \
>> +               : [__mask] "=r" (__mask));                      \
>> +       (__mask & val);                                         \
>> +})
-- 
Thanks and Regards,
Prateek


  reply	other threads:[~2026-04-03 10:35 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-02 11:22 [PATCH v3 0/7] futex: Use runtime constants for futex_hash computation K Prateek Nayak
2026-04-02 11:22 ` [PATCH v3 1/7] x86/runtime-const: Introduce runtime_const_mask_32() K Prateek Nayak
2026-04-02 11:22 ` [PATCH v3 2/7] arm64/runtime-const: Use aarch64_insn_patch_text_nosync() for patching K Prateek Nayak
2026-04-10  9:37   ` Catalin Marinas
2026-04-02 11:22 ` [PATCH v3 3/7] arm64/runtime-const: Introduce runtime_const_mask_32() K Prateek Nayak
2026-04-02 11:22 ` [PATCH v3 4/7] riscv/runtime-const: " K Prateek Nayak
2026-04-03  9:42   ` Guo Ren
2026-04-03 10:35     ` K Prateek Nayak [this message]
2026-04-02 11:22 ` [PATCH v3 5/7] s390/runtime-const: " K Prateek Nayak
2026-04-02 11:22 ` [PATCH v3 6/7] asm-generic/runtime-const: Add dummy runtime_const_mask_32() K Prateek Nayak
2026-04-02 11:22 ` [PATCH v3 7/7] futex: Use runtime constants for __futex_hash() hot path K Prateek Nayak

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