From 1f6a93e4c35e75d547b51f56ba8139ab1a91628c Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Sat, 30 Aug 2008 11:40:24 +1000 Subject: powerpc: Make it possible to move the interrupt handlers away from the kernel This changes the way that the exception prologs transfer control to the handlers in 64-bit kernels with the aim of making it possible to have the prologs separate from the main body of the kernel. Now, instead of computing the address of the handler by taking the top 32 bits of the paca address (to get the 0xc0000000........ part) and ORing in something in the bottom 16 bits, we get the base address of the kernel by doing a load from the paca and add an offset. This also replaces an mfmsr and an ori to compute the MSR value for the handler with a load from the paca. That makes it unnecessary to have a separate version of EXCEPTION_PROLOG_PSERIES that forces 64-bit mode. We can no longer use a direct branches in the exception prolog code, which means that the SLB miss handlers can't branch directly to .slb_miss_realmode any more. Instead we have to compute the address and do an indirect branch. This is conditional on CONFIG_RELOCATABLE; for non-relocatable kernels we use a direct branch as before. (A later change will allow CONFIG_RELOCATABLE to be set on 64-bit powerpc.) Since the secondary CPUs on pSeries start execution in the first 0x100 bytes of real memory and then have to get to wherever the kernel is, we can't use a direct branch to get there. Instead this changes __secondary_hold_spinloop from a flag to a function pointer. When it is set to a non-NULL value, the secondary CPUs jump to the function pointed to by that value. Finally this eliminates one code difference between 32-bit and 64-bit by making __secondary_hold be the text address of the secondary CPU spinloop rather than a function descriptor for it. Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/paca.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/powerpc/kernel/paca.c') diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c index c9bf17eec31b..623e8c3c57f9 100644 --- a/arch/powerpc/kernel/paca.c +++ b/arch/powerpc/kernel/paca.c @@ -79,6 +79,8 @@ void __init initialise_pacas(void) new_paca->lock_token = 0x8000; new_paca->paca_index = cpu; new_paca->kernel_toc = kernel_toc; + new_paca->kernelbase = KERNELBASE; + new_paca->kernel_msr = MSR_KERNEL; new_paca->hw_cpu_id = 0xffff; new_paca->slb_shadow_ptr = &slb_shadow[cpu]; new_paca->__current = &init_task; -- cgit v1.2.2 From 549e8152de8039506f69c677a4546e5427aa6ae7 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Sat, 30 Aug 2008 11:43:47 +1000 Subject: powerpc: Make the 64-bit kernel as a position-independent executable This implements CONFIG_RELOCATABLE for 64-bit by making the kernel as a position-independent executable (PIE) when it is set. This involves processing the dynamic relocations in the image in the early stages of booting, even if the kernel is being run at the address it is linked at, since the linker does not necessarily fill in words in the image for which there are dynamic relocations. (In fact the linker does fill in such words for 64-bit executables, though not for 32-bit executables, so in principle we could avoid calling relocate() entirely when we're running a 64-bit kernel at the linked address.) The dynamic relocations are processed by a new function relocate(addr), where the addr parameter is the virtual address where the image will be run. In fact we call it twice; once before calling prom_init, and again when starting the main kernel. This means that reloc_offset() returns 0 in prom_init (since it has been relocated to the address it is running at), which necessitated a few adjustments. This also changes __va and __pa to use an equivalent definition that is simpler. With the relocatable kernel, PAGE_OFFSET and MEMORY_START are constants (for 64-bit) whereas PHYSICAL_START is a variable (and KERNELBASE ideally should be too, but isn't yet). With this, relocatable kernels still copy themselves down to physical address 0 and run there. Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/paca.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/kernel/paca.c') diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c index 623e8c3c57f9..48a347133f41 100644 --- a/arch/powerpc/kernel/paca.c +++ b/arch/powerpc/kernel/paca.c @@ -12,6 +12,7 @@ #include #include +#include /* This symbol is provided by the linker - let it fill in the paca * field correctly */ @@ -79,7 +80,7 @@ void __init initialise_pacas(void) new_paca->lock_token = 0x8000; new_paca->paca_index = cpu; new_paca->kernel_toc = kernel_toc; - new_paca->kernelbase = KERNELBASE; + new_paca->kernelbase = (unsigned long) _stext; new_paca->kernel_msr = MSR_KERNEL; new_paca->hw_cpu_id = 0xffff; new_paca->slb_shadow_ptr = &slb_shadow[cpu]; -- cgit v1.2.2