coresight: tmc: Fix overflow when calculating is bigger than 2GiB

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When specifying a 2GB AUX buffer, the ETR driver ends up allocating only
a 1MB buffer instead:

  # echo 'file coresight-tmc-etr.c +p' > \
	/sys/kernel/debug/dynamic_debug/control
  # perf record -e cs_etm/@tmc_etr0,timestamp=0/u -C 0 -m ,2G -- test
  coresight tmc_etr0: allocated buffer of size 1024KB in mode 0

The page index is an 'int' type, and shifting it by PAGE_SHIFT overflows
when the resulting value exceeds 2GB.  This produces a negative value,
causing the driver to fall back to the minimum buffer size (1MB).

Cast the page index to a wider type to accommodate large buffer sizes.
Also fix a similar issue in the buffer offset calculation.

Reported-by: Michiel van Tol <michiel.vantol@arm.com>
Fixes: 99443ea19e ("coresight: Add generic TMC sg table framework")
Fixes: eebe8dbd86 ("coresight: tmc: Decouple the perf buffer allocation from sysfs mode")
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20260217-arm_coresight_fix_big_buffer_size-v1-1-774e893d8e3f@arm.com

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This commit is contained in:

Leo Yan 2026-02-17 13:19:43 +00:00 • committed by Suzuki K Poulose

parent 551bb2fd5e

commit f195d54dee

1 changed files with 2 additions and 2 deletions

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drivers/hwtracing/coresight/coresight-tmc-etr.c

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