diff options
| author | Sandrine Bailleux <sandrine.bailleux@arm.com> | 2018-12-20 14:57:16 +0100 |
|---|---|---|
| committer | Sandrine Bailleux <sandrine.bailleux@arm.com> | 2018-12-20 16:29:31 +0100 |
| commit | ba7695b39bb82d5ceba093b0c18dd38cc9af61c3 (patch) | |
| tree | bd7dd5eb9dc1a690a2c8fb8531197bc354e60d30 /lib | |
| parent | d01a4c64411249d6011f1690f1cea15f106198e4 (diff) | |
Fix waitus()
waitus() was missing an instruction barrier before reading the system
counter value. As a result, the CPU could speculatively read it and
we would potentially base our delay loop on stale values.
waitus() now uses the syscounter_read() helper function introduced in
the previous patch, which has the required ISB.
Change-Id: Ic37254485a9cdc4d4d2c86d245aa3273454e82ff
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/delay/delay.c | 16 |
1 files changed, 4 insertions, 12 deletions
diff --git a/lib/delay/delay.c b/lib/delay/delay.c index d88e500..f6b29d1 100644 --- a/lib/delay/delay.c +++ b/lib/delay/delay.c @@ -5,22 +5,14 @@ */ #include <arch_helpers.h> -#include <tftf.h> void waitus(uint64_t us) { - uint64_t cntp_ct_val_base; - uint32_t cnt_frq; - uint64_t wait_cycles; + uint64_t start_count_val = syscounter_read(); + uint64_t wait_cycles = (us * read_cntfrq_el0()) / 1000000; - cnt_frq = read_cntfrq_el0(); - cntp_ct_val_base = read_cntpct_el0(); - - /* Waitms in terms of counter freq */ - wait_cycles = (us * cnt_frq) / 1000000; - - while (read_cntpct_el0() - cntp_ct_val_base < wait_cycles) - ; + while ((syscounter_read() - start_count_val) < wait_cycles) + /* Busy wait... */; } void waitms(uint64_t ms) |