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99aabc6b84
Set the scratch allocation alignment to cacheline size specified by riscv,cbom-block-size in the DTS file to avoid two atomic variables from the same cache line causing livelock on some platforms. If the cacheline is not specified, we set it a default value. Signed-off-by: Raj Vishwanathan <Raj.Vishwanathan@gmail.com> Reviewed-by: Anup Patel <anup@brainfault.org> Reviewed-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20250423225045.267983-1-Raj.Vishwanathan@gmail.com Signed-off-by: Anup Patel <anup@brainfault.org>
144 lines
3.3 KiB
C
144 lines
3.3 KiB
C
/*
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2019 Western Digital Corporation or its affiliates.
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*
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* Authors:
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* Anup Patel <anup.patel@wdc.com>
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*/
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#include <sbi/riscv_locks.h>
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#include <sbi/sbi_hart.h>
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#include <sbi/sbi_hartmask.h>
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#include <sbi/sbi_platform.h>
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#include <sbi/sbi_scratch.h>
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#include <sbi/sbi_string.h>
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#define DEFAULT_SCRATCH_ALLOC_ALIGN __SIZEOF_POINTER__
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u32 sbi_scratch_hart_count;
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u32 hartindex_to_hartid_table[SBI_HARTMASK_MAX_BITS] = { [0 ... SBI_HARTMASK_MAX_BITS-1] = -1U };
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struct sbi_scratch *hartindex_to_scratch_table[SBI_HARTMASK_MAX_BITS];
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static spinlock_t extra_lock = SPIN_LOCK_INITIALIZER;
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static unsigned long extra_offset = SBI_SCRATCH_EXTRA_SPACE_OFFSET;
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/*
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* Get the alignment size.
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* Return DEFAULT_SCRATCH_ALLOC_ALIGNMENT or riscv,cbom_block_size
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*/
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static unsigned long sbi_get_scratch_alloc_align(void)
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{
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const struct sbi_platform *plat = sbi_platform_thishart_ptr();
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if (!plat || !plat->cbom_block_size)
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return DEFAULT_SCRATCH_ALLOC_ALIGN;
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return plat->cbom_block_size;
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}
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u32 sbi_hartid_to_hartindex(u32 hartid)
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{
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sbi_for_each_hartindex(i)
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if (hartindex_to_hartid_table[i] == hartid)
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return i;
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return -1U;
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}
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typedef struct sbi_scratch *(*hartid2scratch)(ulong hartid, ulong hartindex);
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int sbi_scratch_init(struct sbi_scratch *scratch)
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{
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u32 h, hart_count;
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const struct sbi_platform *plat = sbi_platform_ptr(scratch);
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hart_count = plat->hart_count;
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if (hart_count > SBI_HARTMASK_MAX_BITS)
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hart_count = SBI_HARTMASK_MAX_BITS;
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sbi_scratch_hart_count = hart_count;
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sbi_for_each_hartindex(i) {
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h = (plat->hart_index2id) ? plat->hart_index2id[i] : i;
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hartindex_to_hartid_table[i] = h;
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hartindex_to_scratch_table[i] =
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((hartid2scratch)scratch->hartid_to_scratch)(h, i);
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}
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return 0;
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}
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unsigned long sbi_scratch_alloc_offset(unsigned long size)
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{
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void *ptr;
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unsigned long ret = 0;
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struct sbi_scratch *rscratch;
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unsigned long scratch_alloc_align = 0;
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/*
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* We have a simple brain-dead allocator which never expects
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* anything to be free-ed hence it keeps incrementing the
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* next allocation offset until it runs-out of space.
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*
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* In future, we will have more sophisticated allocator which
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* will allow us to re-claim free-ed space.
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*/
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if (!size)
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return 0;
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scratch_alloc_align = sbi_get_scratch_alloc_align();
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/*
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* We let the allocation align to cacheline bytes to avoid livelock on
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* certain platforms due to atomic variables from the same cache line.
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*/
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size += scratch_alloc_align - 1;
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size &= ~(scratch_alloc_align - 1);
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spin_lock(&extra_lock);
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if (SBI_SCRATCH_SIZE < (extra_offset + size))
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goto done;
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ret = extra_offset;
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extra_offset += size;
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done:
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spin_unlock(&extra_lock);
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if (ret) {
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sbi_for_each_hartindex(i) {
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rscratch = sbi_hartindex_to_scratch(i);
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if (!rscratch)
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continue;
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ptr = sbi_scratch_offset_ptr(rscratch, ret);
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sbi_memset(ptr, 0, size);
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}
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}
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return ret;
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}
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void sbi_scratch_free_offset(unsigned long offset)
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{
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if ((offset < SBI_SCRATCH_EXTRA_SPACE_OFFSET) ||
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(SBI_SCRATCH_SIZE <= offset))
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return;
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/*
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* We don't actually free-up because it's a simple
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* brain-dead allocator.
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*/
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}
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unsigned long sbi_scratch_used_space(void)
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{
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unsigned long ret = 0;
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spin_lock(&extra_lock);
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ret = extra_offset;
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spin_unlock(&extra_lock);
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return ret;
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}
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