From: Matthew Leach Date: Fri, 11 Oct 2013 13:52:18 +0000 (+0100) Subject: arm64: big-endian: write CPU holding pen address as LE X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=710be9ac4ea0d2e02a2c4aa625795e65bf3db5b1;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git arm64: big-endian: write CPU holding pen address as LE 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 Signed-off-by: Catalin Marinas --- diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c index 27f08367a6e7..44c22805d2e2 100644 --- a/arch/arm64/kernel/smp_spin_table.c +++ b/arch/arm64/kernel/smp_spin_table.c @@ -72,7 +72,16 @@ static int smp_spin_table_cpu_prepare(unsigned 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])); /*