linux-kernel - [tip: perf/core] perf/x86/intel/pt: Fix a topa

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Message-ID: <172021360691.2215.16485051876594607373.tip-bot2@tip-bot2>
Date: Fri, 05 Jul 2024 21:06:46 -0000
From: "tip-bot2 for Adrian Hunter" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Dave Hansen <dave.hansen@...ux.intel.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, stable@...r.kernel.org,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: perf/core] perf/x86/intel/pt: Fix a topa_entry base address calculation

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     ad97196379d0b8cb24ef3d5006978a6554e6467f
Gitweb:        https://git.kernel.org/tip/ad97196379d0b8cb24ef3d5006978a6554e6467f
Author:        Adrian Hunter <adrian.hunter@...el.com>
AuthorDate:    Mon, 24 Jun 2024 23:10:56 +03:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 04 Jul 2024 16:00:21 +02:00

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@...ux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20240624201101.60186-3-adrian.hunter@intel.com
---
 arch/x86/events/intel/pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 14db6d9..047a2cd 100644
--- 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);
 }
 
 /**