diff options
| author | Akira Tsukamoto <akira.tsukamoto@gmail.com> | 2021-07-20 17:50:52 +0900 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2021-07-23 17:48:52 -0700 |
| commit | 6010d300f9f7e16d1bf327b4730bcd0c0886d9e6 (patch) | |
| tree | cb9a13e091564601e86ccc04f4e5424a1399cb27 | |
| parent | 76f5dfacfb42b75e5782c017827877cfcee20474 (diff) | |
riscv: __asm_copy_to-from_user: Fix: overrun copy
There were two causes for the overrun memory access.
The threshold size was too small.
The aligning dst require one SZREG and unrolling word copy requires
8*SZREG, total have to be at least 9*SZREG.
Inside the unrolling copy, the subtracting -(8*SZREG-1) would make
iteration happening one extra loop. Proper value is -(8*SZREG).
Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
Fixes: ca6eaaa210de ("riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
| -rw-r--r-- | arch/riscv/lib/uaccess.S | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index bceb0629e440..8bbeca89a93f 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -35,7 +35,7 @@ ENTRY(__asm_copy_from_user) /* * Use byte copy only if too small. */ - li a3, 8*SZREG /* size must be larger than size in word_copy */ + li a3, 9*SZREG /* size must be larger than size in word_copy */ bltu a2, a3, .Lbyte_copy_tail /* @@ -75,7 +75,7 @@ ENTRY(__asm_copy_from_user) * a3 - a1 & mask:(SZREG-1) * t0 - end of aligned dst */ - addi t0, t0, -(8*SZREG-1) /* not to over run */ + addi t0, t0, -(8*SZREG) /* not to over run */ 2: fixup REG_L a4, 0(a1), 10f fixup REG_L a5, SZREG(a1), 10f @@ -97,7 +97,7 @@ ENTRY(__asm_copy_from_user) addi a1, a1, 8*SZREG bltu a0, t0, 2b - addi t0, t0, 8*SZREG-1 /* revert to original value */ + addi t0, t0, 8*SZREG /* revert to original value */ j .Lbyte_copy_tail .Lshift_copy: |