lib: sbi: Optimize sbi_tlb

Originally, the process and sync of sbi_tlb need to wait for each other.
Evasion by atomic addition and subtraction.

Signed-off-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>

diff --git a/lib/sbi/sbi_tlb.c b/lib/sbi/sbi_tlb.c
index 4c142ea..d950c45 100644 (file)
--- a/lib/sbi/sbi_tlb.c
+++ b/lib/sbi/sbi_tlb.c
@@ -215,7 +215,7 @@ static void tlb_entry_process(struct sbi_tlb_info *tinfo)
 {
        u32 rhartid;
        struct sbi_scratch *rscratch = NULL;
-       unsigned long *rtlb_sync = NULL;
+       atomic_t *rtlb_sync = NULL;
 
        tinfo->local_fn(tinfo);
 
@@ -225,7 +225,7 @@ static void tlb_entry_process(struct sbi_tlb_info *tinfo)
                        continue;
 
                rtlb_sync = sbi_scratch_offset_ptr(rscratch, tlb_sync_off);
-               while (atomic_raw_xchg_ulong(rtlb_sync, 1)) ;
+               atomic_sub_return(rtlb_sync, 1);
        }
 }
 
@@ -257,10 +257,10 @@ static void tlb_process(struct sbi_scratch *scratch)
 
 static void tlb_sync(struct sbi_scratch *scratch)
 {
-       unsigned long *tlb_sync =
+       atomic_t *tlb_sync =
                        sbi_scratch_offset_ptr(scratch, tlb_sync_off);
 
-       while (!atomic_raw_xchg_ulong(tlb_sync, 0)) {
+       while (atomic_read(tlb_sync) > 0) {
                /*
                 * While we are waiting for remote hart to set the sync,
                 * consume fifo requests to avoid deadlock.
@@ -343,6 +343,7 @@ static int tlb_update(struct sbi_scratch *scratch,
                          u32 remote_hartid, void *data)
 {
        int ret;
+       atomic_t *tlb_sync;
        struct sbi_fifo *tlb_fifo_r;
        struct sbi_tlb_info *tinfo = data;
        u32 curr_hartid = current_hartid();
@@ -369,11 +370,8 @@ static int tlb_update(struct sbi_scratch *scratch,
        tlb_fifo_r = sbi_scratch_offset_ptr(remote_scratch, tlb_fifo_off);
 
        ret = sbi_fifo_inplace_update(tlb_fifo_r, data, tlb_update_cb);
-       if (ret != SBI_FIFO_UNCHANGED) {
-               return 1;
-       }
 
-       while (sbi_fifo_enqueue(tlb_fifo_r, data) < 0) {
+       while (ret == SBI_FIFO_UNCHANGED && sbi_fifo_enqueue(tlb_fifo_r, data) < 0) {
                /**
                 * For now, Busy loop until there is space in the fifo.
                 * There may be case where target hart is also
@@ -387,6 +385,9 @@ static int tlb_update(struct sbi_scratch *scratch,
                            curr_hartid, remote_hartid);
        }
 
+       tlb_sync = sbi_scratch_offset_ptr(scratch, tlb_sync_off);
+       atomic_add_return(tlb_sync, 1);
+
        return 0;
 }
 
@@ -413,7 +414,7 @@ int sbi_tlb_init(struct sbi_scratch *scratch, bool cold_boot)
 {
        int ret;
        void *tlb_mem;
-       unsigned long *tlb_sync;
+       atomic_t *tlb_sync;
        struct sbi_fifo *tlb_q;
        const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
@@ -455,7 +456,7 @@ int sbi_tlb_init(struct sbi_scratch *scratch, bool cold_boot)
        tlb_q = sbi_scratch_offset_ptr(scratch, tlb_fifo_off);
        tlb_mem = sbi_scratch_offset_ptr(scratch, tlb_fifo_mem_off);
 
-       *tlb_sync = 0;
+       ATOMIC_INIT(tlb_sync, 0);
 
        sbi_fifo_init(tlb_q, tlb_mem,
                      SBI_TLB_FIFO_NUM_ENTRIES, SBI_TLB_INFO_SIZE);