From mboxrd@z Thu Jan 1 00:00:00 1970 From: matthew.leach@arm.com (Matthew Leach) Date: Fri, 11 Oct 2013 14:52:18 +0100 Subject: [PATCH 12/14] arm64: big-endian: write CPU holding pen address as LE In-Reply-To: <1381499540-28794-1-git-send-email-matthew.leach@arm.com> References: <1381499540-28794-1-git-send-email-matthew.leach@arm.com> Message-ID: <1381499540-28794-13-git-send-email-matthew.leach@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Currently when CPUs are brought online via a spin-table, the address they should jump to is written to the cpu-release-addr in the kernel's native endianness. As the kernel may switch endianness, secondaries might read the value byte-reversed from what was intended, and they would jump to the wrong address. As the only current arm64 spin-table implementations are little-endian, stricten up the arm64 spin-table definition such that the value written to cpu-release-addr is _always_ little-endian regardless of the endianness of any CPU. If a spinning CPU is operating big-endian, it must byte-reverse the value before jumping to handle this. Signed-off-by: Matthew Leach --- arch/arm64/kernel/smp_spin_table.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c index 7c35fa6..c0bc097 100644 --- a/arch/arm64/kernel/smp_spin_table.c +++ b/arch/arm64/kernel/smp_spin_table.c @@ -48,7 +48,16 @@ static int __init smp_spin_table_prepare_cpu(int cpu) return -ENODEV; release_addr = __va(cpu_release_addr[cpu]); - release_addr[0] = (void *)__pa(secondary_holding_pen); + + /* + * We write the release address as LE regardless of the native + * endianess of the kernel. Therefore, any boot-loaders that + * read this address need to convert this address to the + * boot-loader's endianess before jumping. This is mandated by + * the boot protocol. + */ + release_addr[0] = (void *) cpu_to_le64(__pa(secondary_holding_pen)); + __flush_dcache_area(release_addr, sizeof(release_addr[0])); /* -- 1.7.9.5