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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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3847dab774
This patch adds the necessary code to patch a running kernel at runtime to improve performance. The current implementation offers a few optimizations variants: - When running a SMP kernel on a single UP processor, unwanted assembler statements like locking functions are overwritten with NOPs. When multiple instructions shall be skipped, one branch instruction is used instead of multiple nop instructions. - In the UP case, some pdtlb and pitlb instructions are patched to become pdtlb,l and pitlb,l which only flushes the CPU-local tlb entries instead of broadcasting the flush to other CPUs in the system and thus may improve performance. - fic and fdc instructions are skipped if no I- or D-caches are installed. This should speed up qemu emulation and cacheless systems. - If no cache coherence is needed for IO operations, the relevant fdc and sync instructions in the sba and ccio drivers are replaced by nops. - On systems which share I- and D-TLBs and thus don't have a seperate instruction TLB, the pitlb instruction is replaced by a nop. Live-patching is done early in the boot process, just after having run the system inventory. No drivers are running and thus no external interrupts should arrive. So the hope is that no TLB exceptions will occur during the patching. If this turns out to be wrong we will probably need to do the patching in real-mode. Signed-off-by: Helge Deller <deller@gmx.de>
73 lines
2.1 KiB
C
73 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/asm-parisc/cache.h
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*/
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#ifndef __ARCH_PARISC_CACHE_H
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#define __ARCH_PARISC_CACHE_H
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#include <asm/alternative.h>
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/*
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* PA 2.0 processors have 64 and 128-byte L2 cachelines; PA 1.1 processors
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* have 32-byte cachelines. The L1 length appears to be 16 bytes but this
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* is not clearly documented.
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*/
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#define L1_CACHE_BYTES 16
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#define L1_CACHE_SHIFT 4
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#ifndef __ASSEMBLY__
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#define SMP_CACHE_BYTES L1_CACHE_BYTES
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#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
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#define __read_mostly __attribute__((__section__(".data..read_mostly")))
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/* Read-only memory is marked before mark_rodata_ro() is called. */
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#define __ro_after_init __read_mostly
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void parisc_cache_init(void); /* initializes cache-flushing */
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void disable_sr_hashing_asm(int); /* low level support for above */
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void disable_sr_hashing(void); /* turns off space register hashing */
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void free_sid(unsigned long);
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unsigned long alloc_sid(void);
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struct seq_file;
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extern void show_cache_info(struct seq_file *m);
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extern int split_tlb;
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extern int dcache_stride;
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extern int icache_stride;
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extern struct pdc_cache_info cache_info;
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void parisc_setup_cache_timing(void);
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#define pdtlb(addr) asm volatile("pdtlb 0(%%sr1,%0)" \
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ALTERNATIVE(ALT_COND_NO_SMP, INSN_PxTLB) \
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: : "r" (addr))
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#define pitlb(addr) asm volatile("pitlb 0(%%sr1,%0)" \
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ALTERNATIVE(ALT_COND_NO_SMP, INSN_PxTLB) \
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ALTERNATIVE(ALT_COND_NO_SPLIT_TLB, INSN_NOP) \
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: : "r" (addr))
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#define pdtlb_kernel(addr) asm volatile("pdtlb 0(%0)" \
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ALTERNATIVE(ALT_COND_NO_SMP, INSN_PxTLB) \
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: : "r" (addr))
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#define asm_io_fdc(addr) asm volatile("fdc %%r0(%0)" \
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ALTERNATIVE(ALT_COND_NO_DCACHE, INSN_NOP) \
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ALTERNATIVE(ALT_COND_NO_IOC_FDC, INSN_NOP) \
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: : "r" (addr))
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#define asm_io_sync() asm volatile("sync" \
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ALTERNATIVE(ALT_COND_NO_DCACHE, INSN_NOP) \
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ALTERNATIVE(ALT_COND_NO_IOC_FDC, INSN_NOP) :: )
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#endif /* ! __ASSEMBLY__ */
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/* Classes of processor wrt: disabling space register hashing */
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#define SRHASH_PCXST 0 /* pcxs, pcxt, pcxt_ */
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#define SRHASH_PCXL 1 /* pcxl */
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#define SRHASH_PA20 2 /* pcxu, pcxu_, pcxw, pcxw_ */
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#endif
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