The branch main has been updated by andrew: URL: https://cgit.FreeBSD.org/src/commit/?id=04f6015706f73c90ba78699953d0d4d0b0237298
commit 04f6015706f73c90ba78699953d0d4d0b0237298 Author: Andrew Turner <[email protected]> AuthorDate: 2021-07-16 12:46:59 +0000 Commit: Andrew Turner <[email protected]> CommitDate: 2021-07-19 21:30:11 +0000 Split out the arm64 ID field comparison function This will be useful in an update for finding which HWCAPS to set. Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D31200 --- sys/arm64/arm64/identcpu.c | 48 ++++++++++++++++++++++++++++++---------------- 1 file changed, 32 insertions(+), 16 deletions(-) diff --git a/sys/arm64/arm64/identcpu.c b/sys/arm64/arm64/identcpu.c index f4ce02791787..f755e004a0a8 100644 --- a/sys/arm64/arm64/identcpu.c +++ b/sys/arm64/arm64/identcpu.c @@ -1147,22 +1147,26 @@ get_kernel_reg(u_int reg, uint64_t *val) return (false); } -static uint64_t -update_lower_register(uint64_t val, uint64_t new_val, u_int shift, - int width, bool sign) +/* + * Compares two field values that may be signed or unsigned. + * Returns: + * < 0 when a is less than b + * = 0 when a equals b + * > 0 when a is greater than b + */ +static int +mrs_field_cmp(uint64_t a, uint64_t b, u_int shift, int width, bool sign) { uint64_t mask; - uint64_t new_field, old_field; - bool update; KASSERT(width > 0 && width < 64, ("%s: Invalid width %d", __func__, width)); mask = (1ul << width) - 1; - new_field = (new_val >> shift) & mask; - old_field = (val >> shift) & mask; + /* Move the field to the lower bits */ + a = (a >> shift) & mask; + b = (b >> shift) & mask; - update = false; if (sign) { /* * The field is signed. Toggle the upper bit so the comparison @@ -1170,17 +1174,29 @@ update_lower_register(uint64_t val, uint64_t new_val, u_int shift, * i.e. those with a 0 bit, larger than negative numbers, * i.e. those with a 1 bit, in an unsigned comparison. */ - if ((new_field ^ (1ul << (width - 1))) < - (old_field ^ (1ul << (width - 1)))) - update = true; - } else { - if (new_field < old_field) - update = true; + a ^= 1ul << (width - 1); + b ^= 1ul << (width - 1); } - if (update) { + return (a - b); +} + +static uint64_t +update_lower_register(uint64_t val, uint64_t new_val, u_int shift, + int width, bool sign) +{ + uint64_t mask; + + KASSERT(width > 0 && width < 64, ("%s: Invalid width %d", __func__, + width)); + + /* + * If the new value is less than the existing value update it. + */ + if (mrs_field_cmp(new_val, val, shift, width, sign) < 0) { + mask = (1ul << width) - 1; val &= ~(mask << shift); - val |= new_field << shift; + val |= new_val & (mask << shift); } return (val); _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all To unsubscribe, send any mail to "[email protected]"
