lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20231127141600.20929-13-brgl@bgdev.pl>
Date:   Mon, 27 Nov 2023 15:15:59 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Elliot Berman <quic_eberman@...cinc.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Guru Das Srinagesh <quic_gurus@...cinc.com>,
        Andrew Halaney <ahalaney@...hat.com>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Alex Elder <elder@...aro.org>,
        Srini Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kernel@...cinc.com,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v6 12/13] firmware: qcom: scm: clarify the comment in qcom_scm_pas_init_image()

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

The "memory protection" mechanism mentioned in the comment is the SHM
Bridge. This is also the reason why we do not convert this call to using
the TZ memory allocator.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Tested-by: Andrew Halaney <ahalaney@...hat.com> # sc8280xp-lenovo-thinkpad-x13s
---
 drivers/firmware/qcom/qcom_scm.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 839773270a21..7ba5cff6e4e7 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -563,9 +563,13 @@ int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size,
 	struct qcom_scm_res res;
 
 	/*
-	 * During the scm call memory protection will be enabled for the meta
-	 * data blob, so make sure it's physically contiguous, 4K aligned and
-	 * non-cachable to avoid XPU violations.
+	 * During the SCM call the hypervisor will make the buffer containing
+	 * the program data into an SHM Bridge. This is why we exceptionally
+	 * must not use the TrustZone memory allocator here as - depending on
+	 * Kconfig - it may already use the SHM Bridge mechanism internally.
+	 *
+	 * If we pass a buffer that is already part of an SHM Bridge to this
+	 * call, it will fail.
 	 */
 	mdata_buf = dma_alloc_coherent(__scm->dev, size, &mdata_phys,
 				       GFP_KERNEL);
-- 
2.40.1

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ