From 067173526c3bbc2eaeefcf6b7b2a9d998b9e8042 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 4 Sep 2010 16:14:20 +0100 Subject: ARM: Provide common header for hard_smp_processor_id() Provide a common header to read the SMP CPU number from the MPIDR. Signed-off-by: Russell King --- arch/arm/include/asm/smp_mpidr.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) create mode 100644 arch/arm/include/asm/smp_mpidr.h (limited to 'arch/arm/include/asm/smp_mpidr.h') diff --git a/arch/arm/include/asm/smp_mpidr.h b/arch/arm/include/asm/smp_mpidr.h new file mode 100644 index 000000000000..7da7105e83e5 --- /dev/null +++ b/arch/arm/include/asm/smp_mpidr.h @@ -0,0 +1,12 @@ +#ifndef ASMARM_SMP_MIDR_H +#define ASMARM_SMP_MIDR_H + +#define hard_smp_processor_id() \ + ({ \ + unsigned int cpunum; \ + __asm__("mrc p15, 0, %0, c0, c0, 5\n" \ + : "=r" (cpunum)); \ + cpunum &= 0x0F; \ + }) + +#endif -- cgit v1.2.1 From f00ec48fadf5e37e7889f14cff900aa70d18b644 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 4 Sep 2010 10:47:48 +0100 Subject: ARM: Allow SMP kernels to boot on UP systems UP systems do not implement all the instructions that SMP systems have, so in order to boot a SMP kernel on a UP system, we need to rewrite parts of the kernel. Do this using an 'alternatives' scheme, where the kernel code and data is modified prior to initialization to replace the SMP instructions, thereby rendering the problematical code ineffectual. We use the linker to generate a list of 32-bit word locations and their replacement values, and run through these replacements when we detect a UP system. Signed-off-by: Russell King --- arch/arm/include/asm/smp_mpidr.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'arch/arm/include/asm/smp_mpidr.h') diff --git a/arch/arm/include/asm/smp_mpidr.h b/arch/arm/include/asm/smp_mpidr.h index 7da7105e83e5..6a9307d64900 100644 --- a/arch/arm/include/asm/smp_mpidr.h +++ b/arch/arm/include/asm/smp_mpidr.h @@ -4,7 +4,12 @@ #define hard_smp_processor_id() \ ({ \ unsigned int cpunum; \ - __asm__("mrc p15, 0, %0, c0, c0, 5\n" \ + __asm__("\n" \ + "1: mrc p15, 0, %0, c0, c0, 5\n" \ + " .pushsection \".alt.smp.init\", \"a\"\n"\ + " .long 1b\n" \ + " mov %0, #0\n" \ + " .popsection" \ : "=r" (cpunum)); \ cpunum &= 0x0F; \ }) -- cgit v1.2.1