1 /*
2 * Copyright (C) 2019 Repk repk@triplefau.lt
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 * https://spdx.org/licenses
6 */
7
8 #include <inttypes.h>
9 #include <stdint.h>
10
11 #include <common/bl_common.h>
12 #include <common/debug.h>
13 #include <arch_helpers.h>
14 #include <plat/common/platform.h>
15 #include <bl31/ea_handle.h>
16
17 #define A53_SERR_INT_AXI_SLVERR_ON_EXTERNAL_ACCESS 0xbf000002
18
19 #if !ENABLE_BACKTRACE
get_el_str(unsigned int el)20 static const char *get_el_str(unsigned int el)
21 {
22 if (el == MODE_EL3) {
23 return "EL3";
24 } else if (el == MODE_EL2) {
25 return "EL2";
26 }
27 return "S-EL1";
28 }
29 #endif /* !ENABLE_BACKTRACE */
30
31 /*
32 * This source file with custom plat_ea_handler function is compiled only when
33 * building TF-A with compile option HANDLE_EA_EL3_FIRST=1
34 */
plat_ea_handler(unsigned int ea_reason,uint64_t syndrome,void * cookie,void * handle,uint64_t flags)35 void plat_ea_handler(unsigned int ea_reason, uint64_t syndrome, void *cookie,
36 void *handle, uint64_t flags)
37 {
38 unsigned int level = (unsigned int)GET_EL(read_spsr_el3());
39
40 /*
41 * Asynchronous External Abort with syndrome 0xbf000002 on Cortex A53
42 * core means SError interrupt caused by AXI SLVERR on external access.
43 *
44 * In most cases this indicates a bug in U-Boot or Linux kernel driver
45 * pci-aardvark.c which implements access to A3700 PCIe config space.
46 * Driver does not wait for PCIe PIO transfer completion and try to
47 * start a new PCIe PIO transfer while previous has not finished yet.
48 * A3700 PCIe controller in this case sends SLVERR via AXI which results
49 * in a fatal Asynchronous SError interrupt on Cortex A53 CPU.
50 *
51 * Following patches fix that bug in U-Boot and Linux kernel drivers:
52 * https://source.denx.de/u-boot/u-boot/-/commit/eccbd4ad8e4e182638eafbfb87ac139c04f24a01
53 * https://git.kernel.org/stable/c/f18139966d072dab8e4398c95ce955a9742e04f7
54 *
55 * As a hacky workaround for unpatched U-Boot and Linux kernel drivers
56 * ignore all asynchronous aborts with that syndrome value received on
57 * CPU from level lower than EL3.
58 *
59 * Because these aborts are delivered on CPU asynchronously, they are
60 * imprecise and we cannot check the real reason of abort and neither
61 * who and why sent this abort. We expect that on A3700 it is always
62 * PCIe controller.
63 *
64 * Hence ignoring all aborts with this syndrome value is just a giant
65 * hack that we need only because of bugs in old U-Boot and Linux kernel
66 * versions and because it was decided that TF-A would implement this
67 * hack for U-Boot and Linux kernel it in this way. New patched U-Boot
68 * and kernel versions do not need it anymore.
69 *
70 * Links to discussion about this workaround:
71 * https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/
72 * https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/
73 * https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541
74 */
75 if (level < MODE_EL3 && ea_reason == ERROR_EA_ASYNC &&
76 syndrome == A53_SERR_INT_AXI_SLVERR_ON_EXTERNAL_ACCESS) {
77 ERROR_NL();
78 ERROR("Ignoring Asynchronous External Abort with"
79 " syndrome 0x%" PRIx64 " received on 0x%lx from %s\n",
80 syndrome, read_mpidr_el1(), get_el_str(level));
81 ERROR("SError interrupt: AXI SLVERR on external access\n");
82 ERROR("This indicates a bug in pci-aardvark.c driver\n");
83 ERROR("Please update U-Boot/Linux to the latest version\n");
84 ERROR_NL();
85 console_flush();
86 return;
87 }
88
89 plat_default_ea_handler(ea_reason, syndrome, cookie, handle, flags);
90 }
91