d0fdc20b04
DCACHE_WORD_ACCESS uses the word-at-a-time API for optimised string
comparisons in the vfs layer.
This patch implements support for load_unaligned_zeropad in much the
same way as has been done for arm64.
Here is the test program and step:
$ cat tt.c
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#define ITERATIONS 1000000
#define PATH "123456781234567812345678123456781"
int main(void)
{
unsigned long i;
struct stat buf;
for (i = 0; i < ITERATIONS; i++)
stat(PATH, &buf);
return 0;
}
$ gcc -O2 tt.c
$ touch 123456781234567812345678123456781
$ time ./a.out
Per my test on T-HEAD C910 platforms, the above test performance is
improved by about 7.5%.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20231225044207.3821-3-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
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* Lennox Wu <lennox.wu@sunplusct.com>
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* Chen Liqin <liqin.chen@sunplusct.com>
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* Copyright (C) 2013 Regents of the University of California
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*/
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#include <linux/bitfield.h>
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#include <linux/extable.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <asm/asm-extable.h>
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#include <asm/ptrace.h>
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static inline unsigned long
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get_ex_fixup(const struct exception_table_entry *ex)
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{
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return ((unsigned long)&ex->fixup + ex->fixup);
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}
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static bool ex_handler_fixup(const struct exception_table_entry *ex,
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struct pt_regs *regs)
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{
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regs->epc = get_ex_fixup(ex);
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return true;
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}
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static inline unsigned long regs_get_gpr(struct pt_regs *regs, unsigned int offset)
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{
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if (unlikely(!offset || offset > MAX_REG_OFFSET))
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return 0;
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return *(unsigned long *)((unsigned long)regs + offset);
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}
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static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset,
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unsigned long val)
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{
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if (unlikely(offset > MAX_REG_OFFSET))
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return;
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if (offset)
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*(unsigned long *)((unsigned long)regs + offset) = val;
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}
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static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
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struct pt_regs *regs)
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{
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int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
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int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
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regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT);
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regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0);
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regs->epc = get_ex_fixup(ex);
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return true;
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}
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static bool
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ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
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struct pt_regs *regs)
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{
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int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->data);
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int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
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unsigned long data, addr, offset;
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addr = regs_get_gpr(regs, reg_addr * sizeof(unsigned long));
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offset = addr & 0x7UL;
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addr &= ~0x7UL;
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data = *(unsigned long *)addr >> (offset * 8);
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regs_set_gpr(regs, reg_data * sizeof(unsigned long), data);
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regs->epc = get_ex_fixup(ex);
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return true;
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}
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bool fixup_exception(struct pt_regs *regs)
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{
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const struct exception_table_entry *ex;
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ex = search_exception_tables(regs->epc);
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if (!ex)
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return false;
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switch (ex->type) {
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case EX_TYPE_FIXUP:
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return ex_handler_fixup(ex, regs);
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case EX_TYPE_BPF:
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return ex_handler_bpf(ex, regs);
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case EX_TYPE_UACCESS_ERR_ZERO:
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return ex_handler_uaccess_err_zero(ex, regs);
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case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
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return ex_handler_load_unaligned_zeropad(ex, regs);
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}
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BUG();
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}
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