[coreboot-gerrit] Change in ...coreboot[master]: cpu/x86/mtrr: Fix _FROM_4G_TOP() macro

[Nico Huber (Code Review)]

Hello Kyösti Mälkki, Paul Menzel, build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/31322

to look at the new patch set (#2).

Change subject: cpu/x86/mtrr: Fix _FROM_4G_TOP() macro
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cpu/x86/mtrr: Fix _FROM_4G_TOP() macro

This macro was unnecessarily complex. Trying to avoid an overflow
for unknown reasons, and instead shifted the result into the sign
bit in C. Using a plain number literal that forces C to use an
adequate integer type seems to be safe. We start with 0xffffffff,
subtract `x` and add 1 again. Turned out to be a common pattern
and can't overflow for any positive 32-bit `x`.

Change-Id: Ibb0c5b88a6e42d3ef2990196a5b99ace90ea8ee8
Signed-off-by: Nico Huber 
---
M src/include/cpu/x86/mtrr.h
1 file changed, 1 insertion(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/22/31322/2