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Optimization of the assembly code of uaccess APIs. #120

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Merged
sterling-teng merged 2 commits into from
Sep 27, 2025
Merged

Optimization of the assembly code of uaccess APIs. #120

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b752bc9
riscv: uaccess: Allow the last potential unrolled copy
uestc-gr Sep 3, 2025
90bffea
riscv: uaccess: Relax the threshold for fast path
uestc-gr Sep 3, 2025
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4 changes: 2 additions & 2 deletions arch/riscv/lib/uaccess.S
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ ENTRY(__asm_copy_from_user)
* Use byte copy only if too small.
* SZREG holds 4 for RV32 and 8 for RV64
*/
li a3, 9*SZREG /* size must be larger than size in word_copy */
li a3, 9*SZREG-1 /* size must >= (word_copy stride + SZREG-1) */
bltu a2, a3, .Lbyte_copy_tail

/*
Expand Down Expand Up @@ -95,7 +95,7 @@ ENTRY(__asm_copy_from_user)
fixup REG_S t4, 7*SZREG(a0), 10f
addi a0, a0, 8*SZREG
addi a1, a1, 8*SZREG
bltu a0, t0, 2b
bleu a0, t0, 2b

addi t0, t0, 8*SZREG /* revert to original value */
j .Lbyte_copy_tail
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