On 4/9/25 10:11, Yu-Chun Lin wrote:
> The custom swap function used in sort() was identical to the default
> built-in sort swap. Remove the custom swap function and passes NULL to
> sort(), allowing it to use the default swap function.
>
> This change reduces code size and improves performance, particularly when
> CONFIG_MITIGATION_RETPOLINE is enabled. With RETPOLINE mitigation, indirect
> function calls incur significant overhead, and using the default swap
> function avoids this cost.
>
> $ ./scripts/bloat-o-meter ./unwind.o.old ./unwind.o.new
> add/remove: 0/1 grow/shrink: 0/1 up/down: 0/-22 (-22)
> Function old new delta
> init_unwind_hdr.constprop 544 540 -4
> swap_eh_frame_hdr_table_entries 18 - -18
> Total: Before=4410, After=4388, chg -0.50%
>
> Signed-off-by: Yu-Chun Lin <eleanor...@gmail.com>
Acked-by: Vineet Gupta <vgu...@kernel.org>
Added to for-curr.
Thx,
-Vineet
> ---
> Compile test only
>
> arch/arc/kernel/unwind.c | 11 +----------
> 1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
> index d8969dab12d4..789cfb9ea14e 100644
> --- a/arch/arc/kernel/unwind.c
> +++ b/arch/arc/kernel/unwind.c
> @@ -241,15 +241,6 @@ static int cmp_eh_frame_hdr_table_entries(const void
> *p1, const void *p2)
> return (e1->start > e2->start) - (e1->start < e2->start);
> }
>
> -static void swap_eh_frame_hdr_table_entries(void *p1, void *p2, int size)
> -{
> - struct eh_frame_hdr_table_entry *e1 = p1;
> - struct eh_frame_hdr_table_entry *e2 = p2;
> -
> - swap(e1->start, e2->start);
> - swap(e1->fde, e2->fde);
> -}
> -
> static void init_unwind_hdr(struct unwind_table *table,
> void *(*alloc) (unsigned long))
> {
> @@ -345,7 +336,7 @@ static void init_unwind_hdr(struct unwind_table *table,
> sort(header->table,
> n,
> sizeof(*header->table),
> - cmp_eh_frame_hdr_table_entries, swap_eh_frame_hdr_table_entries);
> + cmp_eh_frame_hdr_table_entries, NULL);
>
> table->hdrsz = hdrSize;
> smp_wmb();
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