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authorJacob Garber <jgarber1@ualberta.ca>2019-03-25 18:20:06 -0600
committerPatrick Georgi <pgeorgi@google.com>2019-04-08 14:15:20 +0000
commitb70c77691ba9a26989fc8922a2e1807f6f8bdd09 (patch)
treede19d4080cc794835ea349874c9d84c690c6166a
parent0decccb666245e38bfd0595e8c7e312c6937c465 (diff)
downloadcoreboot-b70c77691ba9a26989fc8922a2e1807f6f8bdd09.tar.xz
nb/intel/pineview: Correct lsbpos(0) and msbpos(0)
lsbpos and msbpos have incorrect behaviour when given 0. lsbpos(0) returns 8, and msbpos(0) hangs. The latter is because the check i >= 0 is always true for an unsigned integer, causing it to loop indefinitely (this was flagged by Coverity). 0 doesn't have a lsb or msb position, so we change both functions to return -1 in this case to indicate an error. The code already guards against calling these functions with 0, but we make this more explicit to prevent errors in the future. Found-by: Coverity Scan, CID 1347356, 1347386 Signed-off-by: Jacob Garber <jgarber1@ualberta.ca> Change-Id: Ic5be50846cc545dcd48593e5ed3fd6068a6104cb Reviewed-on: https://review.coreboot.org/c/coreboot/+/32054 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com>
-rw-r--r--src/northbridge/intel/pineview/raminit.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/src/northbridge/intel/pineview/raminit.c b/src/northbridge/intel/pineview/raminit.c
index fa5122afc6..bf00099bab 100644
--- a/src/northbridge/intel/pineview/raminit.c
+++ b/src/northbridge/intel/pineview/raminit.c
@@ -326,18 +326,24 @@ static u32 ddr_reg_to_mhz(u32 speed)
}
#endif
-static u8 lsbpos(u8 val) //Forward
+// Return the position of the least significant set bit, 0-indexed.
+// 0 does not have a lsb, so return -1 for error.
+static int lsbpos(u8 val)
{
- u8 i;
- for (i = 0; (i < 8) && ((val & (1 << i)) == 0); i++);
- return i;
+ for (int i = 0; i < 8; i++)
+ if (val & (1 << i))
+ return i;
+ return -1;
}
-static u8 msbpos(u8 val) //Reverse
+// Return the position of the most significant set bit, 0-indexed.
+// 0 does not have a msb, so return -1 for error.
+static int msbpos(u8 val)
{
- u8 i;
- for (i = 7; (i >= 0) && ((val & (1 << i)) == 0); i--);
- return i;
+ for (int i = 7; i >= 0; i--)
+ if (val & (1 << i))
+ return i;
+ return -1;
}
static void sdram_detect_smallest_params(struct sysinfo *s)
@@ -443,10 +449,14 @@ static void sdram_detect_ram_speed(struct sysinfo *s)
die("No common CAS among dimms\n");
}
+ // commoncas is nonzero, so these calls will not error
+ u8 msbp = (u8)msbpos(commoncas);
+ u8 lsbp = (u8)lsbpos(commoncas);
+
// Start with fastest common CAS
cas = 0;
- highcas = msbpos(commoncas);
- lowcas = max(lsbpos(commoncas), 5);
+ highcas = msbp;
+ lowcas = max(lsbp, 5);
while (cas == 0 && highcas >= lowcas) {
FOR_EACH_POPULATED_DIMM(s->dimms, i) {
@@ -484,8 +494,8 @@ static void sdram_detect_ram_speed(struct sysinfo *s)
die("Timings not supported by MCH\n");
}
cas = 0;
- highcas = msbpos(commoncas);
- lowcas = lsbpos(commoncas);
+ highcas = msbp;
+ lowcas = lsbp;
while (cas == 0 && highcas >= lowcas) {
FOR_EACH_POPULATED_DIMM(s->dimms, i) {
switch (freq) {