| Brad Bishop | bec4ebc | 2022-08-03 09:55:16 -0400 | [diff] [blame] | 1 | From 8271c21bcff260295203214b7b8c87cdb8236453 Mon Sep 17 00:00:00 2001 |
| 2 | From: Jaxson Han <jaxson.han@arm.com> |
| 3 | Date: Tue, 4 Jan 2022 17:01:55 +0800 |
| 4 | Subject: [PATCH] boot: Add the --enable-keep-el compile option |
| 5 | |
| 6 | Add --enable-keep-el compile option to enable boot-wrapper booting next |
| 7 | stage at EL2. |
| 8 | The Armv8R AArch64 boots at EL2. If the next stage requires EL2 booting, |
| 9 | the boot-wrapper should not drop to EL1. |
| 10 | Currently, this option only works for Armv8R AArch64. Also, to work with |
| 11 | Linux PSCI, this option will cause secondary cores booting at EL1. |
| 12 | |
| 13 | Issue-Id: SCM-3813 |
| 14 | Upstream-Status: Inappropriate [other] |
| 15 | Implementation pending further discussion |
| 16 | Signed-off-by: Jaxson Han <jaxson.han@arm.com> |
| 17 | Change-Id: I3ba9c87cf0b59d163ca433f74c9e3a46e5ca2c63 |
| 18 | --- |
| 19 | Makefile.am | 4 ++++ |
| 20 | arch/aarch64/boot.S | 6 +++++- |
| 21 | common/psci.c | 6 ++++++ |
| 22 | configure.ac | 5 +++++ |
| 23 | 4 files changed, 20 insertions(+), 1 deletion(-) |
| 24 | |
| 25 | diff --git a/Makefile.am b/Makefile.am |
| 26 | index 734de92..054becd 100644 |
| 27 | --- a/Makefile.am |
| 28 | +++ b/Makefile.am |
| 29 | @@ -33,6 +33,10 @@ PSCI_CPU_ON := 0xc4000003 |
| 30 | endif |
| 31 | PSCI_CPU_OFF := 0x84000002 |
| 32 | |
| 33 | +if KEEP_EL |
| 34 | +DEFINES += -DKEEP_EL |
| 35 | +endif |
| 36 | + |
| 37 | COMMON_SRC := common/ |
| 38 | COMMON_OBJ := boot.o bakery_lock.o platform.o lib.o device_tree.o |
| 39 | |
| 40 | diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S |
| 41 | index 6dbd5cc..157c097 100644 |
| 42 | --- a/arch/aarch64/boot.S |
| 43 | +++ b/arch/aarch64/boot.S |
| 44 | @@ -233,7 +233,11 @@ el2_init: |
| 45 | msr cnthctl_el2, x0 |
| 46 | isb |
| 47 | |
| 48 | +#ifdef KEEP_EL |
| 49 | + mov w0, #SPSR_KERNEL |
| 50 | +#else |
| 51 | mov w0, #SPSR_KERNEL_EL1 |
| 52 | +#endif |
| 53 | ldr x1, =spsr_to_elx |
| 54 | str w0, [x1] |
| 55 | // fall through |
| 56 | @@ -313,5 +317,5 @@ ASM_FUNC(jump_kernel) |
| 57 | .align 3 |
| 58 | flag_keep_el: |
| 59 | .long 0 |
| 60 | -spsr_to_elx: |
| 61 | +ASM_DATA(spsr_to_elx) |
| 62 | .long 0 |
| 63 | diff --git a/common/psci.c b/common/psci.c |
| 64 | index a0e8700..945780b 100644 |
| 65 | --- a/common/psci.c |
| 66 | +++ b/common/psci.c |
| 67 | @@ -18,6 +18,8 @@ |
| 68 | #error "No MPIDRs provided" |
| 69 | #endif |
| 70 | |
| 71 | +extern unsigned int spsr_to_elx; |
| 72 | + |
| 73 | static unsigned long branch_table[NR_CPUS]; |
| 74 | |
| 75 | bakery_ticket_t branch_table_lock[NR_CPUS]; |
| 76 | @@ -44,6 +46,10 @@ static int psci_cpu_on(unsigned long target_mpidr, unsigned long address) |
| 77 | ret = psci_store_address(cpu, address); |
| 78 | bakery_unlock(branch_table_lock, this_cpu); |
| 79 | |
| 80 | +#ifdef KEEP_EL |
| 81 | + spsr_to_elx = SPSR_KERNEL_EL1; |
| 82 | +#endif |
| 83 | + |
| 84 | return ret; |
| 85 | } |
| 86 | |
| 87 | diff --git a/configure.ac b/configure.ac |
| 88 | index 53e51be..0e07db3 100644 |
| 89 | --- a/configure.ac |
| 90 | +++ b/configure.ac |
| 91 | @@ -25,6 +25,11 @@ AS_IF([test "x$BOOTWRAPPER_ES" = x32 -a "x$KERNEL_ES" != x32], |
| 92 | [AC_MSG_ERROR([a 32-bit boot-wrapper cannot launch a 64-bit kernel])] |
| 93 | ) |
| 94 | |
| 95 | +AC_ARG_ENABLE([keep-el], |
| 96 | + AC_HELP_STRING([--enable-keep-el], [keep exception level when start kernel]), |
| 97 | + [KEEP_EL=yes], [KEEP_EL=no]) |
| 98 | +AM_CONDITIONAL([KEEP_EL], [test "x$KEEP_EL" = xyes]) |
| 99 | + |
| 100 | # Allow a user to pass --with-kernel-dir |
| 101 | AC_ARG_WITH([kernel-dir], |
| 102 | AS_HELP_STRING([--with-kernel-dir], [specify the root Linux kernel build directory (required)]), |