It is not immediately obvious what the expected inputs to these fault handlers is and how they calculate the number of unset bytes. Having stared deeply at this in order to fix some corner cases, add some comments to addist those who follow.
Signed-off-by: Matt Redfearn <[email protected]> --- Changes in v2: - Add comments to fault handlers in new, separate, patch. arch/mips/lib/memset.S | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/mips/lib/memset.S b/arch/mips/lib/memset.S index 1cc306520a55..a06dabe99d4b 100644 --- a/arch/mips/lib/memset.S +++ b/arch/mips/lib/memset.S @@ -231,16 +231,25 @@ #ifdef CONFIG_CPU_MIPSR6 .Lbyte_fixup\@: + /* + * unset_bytes = current_addr + 1 + * a2 = t0 + 1 + */ PTR_SUBU a2, $0, t0 jr ra PTR_ADDIU a2, 1 #endif /* CONFIG_CPU_MIPSR6 */ .Lfirst_fixup\@: + /* unset_bytes already in a2 */ jr ra nop .Lfwd_fixup\@: + /* + * unset_bytes = partial_start_addr + #bytes - fault_addr + * a2 = t1 + (a2 & 3f) - $28->task->BUADDR + */ PTR_L t0, TI_TASK($28) andi a2, 0x3f LONG_L t0, THREAD_BUADDR(t0) @@ -249,6 +258,10 @@ LONG_SUBU a2, t0 .Lpartial_fixup\@: + /* + * unset_bytes = partial_end_addr + #bytes - fault_addr + * a2 = a0 + (a2 & STORMASK) - $28->task->BUADDR + */ PTR_L t0, TI_TASK($28) andi a2, STORMASK LONG_L t0, THREAD_BUADDR(t0) @@ -257,10 +270,15 @@ LONG_SUBU a2, t0 .Llast_fixup\@: + /* unset_bytes already in a2 */ jr ra nop .Lsmall_fixup\@: + /* + * unset_bytes = end_addr - current_addr + 1 + * a2 = t1 - a0 + 1 + */ PTR_SUBU a2, t1, a0 jr ra PTR_ADDIU a2, 1 -- 2.7.4
