63 lines
2.4 KiB
Diff
63 lines
2.4 KiB
Diff
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From dae39d461569897f3ae0aedde041dfb8cfcc4f96 Mon Sep 17 00:00:00 2001
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From: Henrik Grimler <henrik@grimler.se>
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Date: Mon, 18 Oct 2021 21:43:08 +0200
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Subject: [PATCH 11/16] ARM: exynos: only do SMC_CMD_CPU1BOOT call on Exynos4
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On Exynos5 the call is simply ignored by most variants of the
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trustzone firmware. However, on some devices it instead causes the
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device to hang, so let's avoid the call for the SoCs where it should
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not be needed.
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To see that the call is ignored, we can look into sboot/tzsw. On most
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of the Exynos{4,5} devices the part of sboot/tzsw that seem to handle
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the secure monitor calls is quite easy to recognise, the SMC number is
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compared to known ones, and if equal it branches to the relevant
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function. In assembly this looks something like:
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;-- handle_smc:
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0x00000514 650070e3 cmn r0, 0x65
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0x00000518 0a00000a beq loc.smc_cmd_reg
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0x0000051c 010070e3 cmn r0, 1
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0x00000520 6c00000a beq loc.smc_cmd_init
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0x00000524 020070e3 cmn r0, 2
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0x00000528 6b00000a beq loc.smc_cmd_info
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0x0000052c 030070e3 cmn r0, 3
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0x00000530 6e00000a beq loc.smc_cmd_sleep
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0x00000534 060070e3 cmn r0, 6
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0x00000538 ae00000a beq loc.smc_cmd_save_state
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0x0000053c 070070e3 cmn r0, 7
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0x00000540 b400000a beq loc.smc_cmd_standby
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0x00000544 2b01001a bne loc.smc_return_minus1
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where above example is from exynos5420-arndale-octa. As can be seen
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the case where r0 is 4 (i.e. SMC_CMD_CPU1BOOT) is not handled. The
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annotations are taken from github.com/hsnaves/exynos5410-firmware,
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where a large part of the exynos5410 trustzone firmware has been
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reverse-engineered.
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Signed-off-by: Henrik Grimler <henrik@grimler.se>
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Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
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---
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arch/arm/mach-exynos/firmware.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/arch/arm/mach-exynos/firmware.c b/arch/arm/mach-exynos/firmware.c
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index 2eaf2dbb8e81..2da5b60b59e2 100644
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--- a/arch/arm/mach-exynos/firmware.c
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+++ b/arch/arm/mach-exynos/firmware.c
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@@ -60,8 +60,10 @@ static int exynos_cpu_boot(int cpu)
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/*
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* Exynos3250 doesn't need to send smc command for secondary CPU boot
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* because Exynos3250 removes WFE in secure mode.
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+ *
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+ * On Exynos5 devices the call is ignored by trustzone firmware.
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*/
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- if (soc_is_exynos3250())
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+ if (!soc_is_exynos4210() && !soc_is_exynos4412())
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return 0;
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/*
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--
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2.34.1
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