perf/x86/intel/pt: Fix a topa_entry base address calculation

topa_entry->base is a bit-field. Bit-fields are not promoted to a 64-bit
type, even if the underlying type is 64-bit, and so, if necessary, must
be cast to a larger type when calculations are done.

Fix a topa_entry->base address calculation by adding a cast.

Without the cast, the address was limited to 36-bits i.e. 64GiB.

The address calculation is used on systems that do not support Multiple
Entry ToPA (only Broadwell), and affects physical addresses on or above
64GiB. Instead of writing to the correct address, the address comprising
the first 36 bits would be written to.

Intel PT snapshot and sampling modes are not affected.

Fixes: 52ca9ced3f70 ("perf/x86/intel/pt: Add Intel PT PMU driver")
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240624201101.60186-3-adrian.hunter@intel.com

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 14db6d9d318b3c76e091c1a91b9649a56622c3b6..047a2cd5b3fe24a815cef6ede1be1f6f06d24f2e 100644 (file)
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -878,7 +878,7 @@ static void pt_update_head(struct pt *pt)
  */
 static void *pt_buffer_region(struct pt_buffer *buf)
 {
-       return phys_to_virt(TOPA_ENTRY(buf->cur, buf->cur_idx)->base << TOPA_SHIFT);
+       return phys_to_virt((phys_addr_t)TOPA_ENTRY(buf->cur, buf->cur_idx)->base << TOPA_SHIFT);
 }
 
 /**