[XS] Change in coreboot[main]: lib/ramdetect: Limit probe size to function argument

[ron minnich (Code Review)]

ron minnich has submitted this change. ( https://review.coreboot.org/c/coreboot/+/68842?usp=email )

Change subject: lib/ramdetect: Limit probe size to function argument
......................................................................

lib/ramdetect: Limit probe size to function argument

This avoids probing above the function argument where other things than
DRAM could be mapped.

Change-Id: Ie7f915c6e150629eff235ee94719172467a54db2
Signed-off-by: Arthur Heymans 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68842
Tested-by: build bot (Jenkins) 
Reviewed-by: ron minnich 
Reviewed-by: Maximilian Brune 
---
M src/lib/ramdetect.c
1 file changed, 4 insertions(+), 1 deletion(-)

Approvals:
  Maximilian Brune: Looks good to me, approved
  build bot (Jenkins): Verified
  ron minnich: Looks good to me, approved

diff --git a/src/lib/ramdetect.c b/src/lib/ramdetect.c
index cfec029..9a29d0f 100644
--- a/src/lib/ramdetect.c
+++ b/src/lib/ramdetect.c
@@ -57,9 +57,12 @@
    msb = MIN(msb, MAX_ADDRESSABLE_SPACE);

/* Compact binary search.  */
-	for (i = msb; i >= 0; i--)
+	for (i = msb; i >= 0; i--) {
+		if ((discovered | (1ULL << i)) > probe_size)
+			continue;
    	if (probe_mb(dram_start, (discovered | (1ULL << i))))
    		discovered |= (1ULL << i);
+	}

saved_result = discovered;
    printk(BIOS_DEBUG, "RAMDETECT: Found %zu MiB RAM\n", discovered);