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McKenney" , Mark Rutland , Bradley Morgan Subject: [PATCH RESEND] arm64: sleep: factor sleep_save_stash slot lookup into a macro Date: Sat, 19 Sep 2026 12:10:44 +0000 Message-ID: <20260919121044.13883-1-brads@mainlining.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Both __cpu_suspend_enter() and _cpu_resume() open code the same MPIDR_EL1 hash lookup to find the current CPU's slot in sleep_save_stash. Factor it into a get_sleep_stash_slot macro. Since that macro would be the only remaining user of compute_mpidr_hash, inline the hash computation into get_sleep_stash_slot and just remove compute_mpidr_hash altogether. No functional change intended. Signed-off-by: Bradley Morgan --- Resending from my new address. arch/arm64/kernel/sleep.S | 103 +++++++++++++++----------------------- 1 file changed, 41 insertions(+), 62 deletions(-) diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S index f093cdf71be1..c1bec489ea76 100644 --- a/arch/arm64/kernel/sleep.S +++ b/arch/arm64/kernel/sleep.S @@ -7,48 +7,48 @@ .text /* - * Implementation of MPIDR_EL1 hash algorithm through shifting + * Compute the address of the current CPU's entry in sleep_save_stash, + * i.e. &sleep_save_stash[hash(MPIDR_EL1)], where the hash is an + * implementation of the MPIDR_EL1 hash algorithm through shifting * and OR'ing. * - * @dst: register containing hash result - * @rs0: register containing affinity level 0 bit shift - * @rs1: register containing affinity level 1 bit shift - * @rs2: register containing affinity level 2 bit shift - * @rs3: register containing affinity level 3 bit shift - * @mpidr: register containing MPIDR_EL1 value - * @mask: register containing MPIDR mask - * * Pseudo C-code: * - *u32 dst; + * u64 mpidr = MPIDR_EL1 & mpidr_hash.mask; + * u32 hash = ((mpidr & 0xff) >> mpidr_hash.shift_aff[0]) | + * ((mpidr & 0xff00) >> mpidr_hash.shift_aff[1]) | + * ((mpidr & 0xff0000) >> mpidr_hash.shift_aff[2]) | + * ((mpidr & 0xff00000000) >> mpidr_hash.shift_aff[3]); + * slot = &sleep_save_stash[hash]; + * + * @slot: output register * - *compute_mpidr_hash(u32 rs0, u32 rs1, u32 rs2, u32 rs3, u64 mpidr, u64 mask) { - * u32 aff0, aff1, aff2, aff3; - * u64 mpidr_masked = mpidr & mask; - * aff0 = mpidr_masked & 0xff; - * aff1 = mpidr_masked & 0xff00; - * aff2 = mpidr_masked & 0xff0000; - * aff3 = mpidr_masked & 0xff00000000; - * dst = (aff0 >> rs0 | aff1 >> rs1 | aff2 >> rs2 | aff3 >> rs3); - *} - * Input registers: rs0, rs1, rs2, rs3, mpidr, mask - * Output register: dst - * Note: input and output registers must be disjoint register sets - (eg: a macro instance with mpidr = x1 and dst = x1 is invalid) + * Clobbers: x2 - x8 */ - .macro compute_mpidr_hash dst, rs0, rs1, rs2, rs3, mpidr, mask - and \mpidr, \mpidr, \mask // mask out MPIDR bits - and \dst, \mpidr, #0xff // mask=aff0 - lsr \dst ,\dst, \rs0 // dst=aff0>>rs0 - and \mask, \mpidr, #0xff00 // mask = aff1 - lsr \mask ,\mask, \rs1 - orr \dst, \dst, \mask // dst|=(aff1>>rs1) - and \mask, \mpidr, #0xff0000 // mask = aff2 - lsr \mask ,\mask, \rs2 - orr \dst, \dst, \mask // dst|=(aff2>>rs2) - and \mask, \mpidr, #0xff00000000 // mask = aff3 - lsr \mask ,\mask, \rs3 - orr \dst, \dst, \mask // dst|=(aff3>>rs3) + .macro get_sleep_stash_slot slot + mrs x3, mpidr_el1 + adr_l x2, mpidr_hash + ldr x8, [x2, #MPIDR_HASH_MASK] + /* + * Following code relies on the struct mpidr_hash + * members size. + */ + ldp w4, w5, [x2, #MPIDR_HASH_SHIFTS] + ldp w6, w7, [x2, #(MPIDR_HASH_SHIFTS + 8)] + and x3, x3, x8 // mask out MPIDR bits + and x2, x3, #0xff // aff0 + lsr x2, x2, x4 // hash = aff0 >> shift_aff[0] + and x8, x3, #0xff00 // aff1 + lsr x8, x8, x5 + orr x2, x2, x8 // hash |= aff1 >> shift_aff[1] + and x8, x3, #0xff0000 // aff2 + lsr x8, x8, x6 + orr x2, x2, x8 // hash |= aff2 >> shift_aff[2] + and x8, x3, #0xff00000000 // aff3 + lsr x8, x8, x7 + orr x2, x2, x8 // hash |= aff3 >> shift_aff[3] + ldr_l \slot, sleep_save_stash + add \slot, \slot, x2, lsl #3 // slot = &sleep_save_stash[hash] .endm /* * Save CPU state in the provided sleep_stack_data area, and publish its @@ -74,20 +74,8 @@ SYM_FUNC_START(__cpu_suspend_enter) mov x2, sp str x2, [x0, #SLEEP_STACK_DATA_SYSTEM_REGS + CPU_CTX_SP] - /* find the mpidr_hash */ - ldr_l x1, sleep_save_stash - mrs x7, mpidr_el1 - adr_l x9, mpidr_hash - ldr x10, [x9, #MPIDR_HASH_MASK] - /* - * Following code relies on the struct mpidr_hash - * members size. - */ - ldp w3, w4, [x9, #MPIDR_HASH_SHIFTS] - ldp w5, w6, [x9, #(MPIDR_HASH_SHIFTS + 8)] - compute_mpidr_hash x8, x3, x4, x5, x6, x7, x10 - add x1, x1, x8, lsl #3 - + /* publish this CPU's sleep_stack_data area in its stash slot */ + get_sleep_stash_slot x1 str x0, [x1] add x0, x0, #SLEEP_STACK_DATA_SYSTEM_REGS stp x29, lr, [sp, #-16]! @@ -117,18 +105,9 @@ SYM_FUNC_START(_cpu_resume) mov x0, x19 bl finalise_el2 - mrs x1, mpidr_el1 - adr_l x8, mpidr_hash // x8 = struct mpidr_hash virt address - - /* retrieve mpidr_hash members to compute the hash */ - ldr x2, [x8, #MPIDR_HASH_MASK] - ldp w3, w4, [x8, #MPIDR_HASH_SHIFTS] - ldp w5, w6, [x8, #(MPIDR_HASH_SHIFTS + 8)] - compute_mpidr_hash x7, x3, x4, x5, x6, x1, x2 - - /* x7 contains hash index, let's use it to grab context pointer */ - ldr_l x0, sleep_save_stash - ldr x0, [x0, x7, lsl #3] + /* retrieve this CPU's context pointer from its stash slot */ + get_sleep_stash_slot x1 + ldr x0, [x1] add x29, x0, #SLEEP_STACK_DATA_CALLEE_REGS add x0, x0, #SLEEP_STACK_DATA_SYSTEM_REGS /* load sp from context */ -- 2.47.3