| Message ID | 20110723074111.GA17927@bloggs.ozlabs.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On 07/23/2011 09:41 AM, Paul Mackerras wrote: > This makes arch/powerpc/kvm/book3s_rmhandlers.S and > arch/powerpc/kvm/book3s_hv_rmhandlers.S be assembled as > separate compilation units rather than having them #included in > arch/powerpc/kernel/exceptions-64s.S. We no longer have any > conditional branches between the exception prologs in > exceptions-64s.S and the KVM handlers, so there is no need to > keep their contents close together in the vmlinux image. > > In their current location, they are using up part of the limited > space between the first-level interrupt handlers and the firmware > NMI data area at offset 0x7000, and with some kernel configurations > this area will overflow (e.g. allyesconfig), leading to an > "attempt to .org backwards" error when compiling exceptions-64s.S. > > Moving them out requires that we add some #includes that the > book3s_{,hv_}rmhandlers.S code was previously getting implicitly > via exceptions-64s.S. So what if your kernel binary is bigger than the 24 bits we can jump and the KVM code happens to be at the end? Or do we just not care here? Alex
On Tue, Aug 02, 2011 at 02:20:28PM +0200, Alexander Graf wrote: > On 07/23/2011 09:41 AM, Paul Mackerras wrote: > >This makes arch/powerpc/kvm/book3s_rmhandlers.S and > >arch/powerpc/kvm/book3s_hv_rmhandlers.S be assembled as > >separate compilation units rather than having them #included in > >arch/powerpc/kernel/exceptions-64s.S. We no longer have any > >conditional branches between the exception prologs in > >exceptions-64s.S and the KVM handlers, so there is no need to > >keep their contents close together in the vmlinux image. > > > >In their current location, they are using up part of the limited > >space between the first-level interrupt handlers and the firmware > >NMI data area at offset 0x7000, and with some kernel configurations > >this area will overflow (e.g. allyesconfig), leading to an > >"attempt to .org backwards" error when compiling exceptions-64s.S. > > > >Moving them out requires that we add some #includes that the > >book3s_{,hv_}rmhandlers.S code was previously getting implicitly > >via exceptions-64s.S. > > So what if your kernel binary is bigger than the 24 bits we can jump > and the KVM code happens to be at the end? Or do we just not care > here? Actually we can jump +/- 32MB (26 bits). I believe that the linker inserts trampolines if the branch target is more than 32MB away, so it should still work if the kernel is really large and the KVM code happens to be at the end. Stephen Rothwell has been asking me about this patch. He wants it in (or something like it) so that he can get his daily linux-next powerpc allyesconfig builds to stop failing. Paul.
Am 11.08.2011 um 01:58 schrieb Paul Mackerras <paulus@samba.org>: > On Tue, Aug 02, 2011 at 02:20:28PM +0200, Alexander Graf wrote: >> On 07/23/2011 09:41 AM, Paul Mackerras wrote: >>> This makes arch/powerpc/kvm/book3s_rmhandlers.S and >>> arch/powerpc/kvm/book3s_hv_rmhandlers.S be assembled as >>> separate compilation units rather than having them #included in >>> arch/powerpc/kernel/exceptions-64s.S. We no longer have any >>> conditional branches between the exception prologs in >>> exceptions-64s.S and the KVM handlers, so there is no need to >>> keep their contents close together in the vmlinux image. >>> >>> In their current location, they are using up part of the limited >>> space between the first-level interrupt handlers and the firmware >>> NMI data area at offset 0x7000, and with some kernel configurations >>> this area will overflow (e.g. allyesconfig), leading to an >>> "attempt to .org backwards" error when compiling exceptions-64s.S. >>> >>> Moving them out requires that we add some #includes that the >>> book3s_{,hv_}rmhandlers.S code was previously getting implicitly >>> via exceptions-64s.S. >> >> So what if your kernel binary is bigger than the 24 bits we can jump >> and the KVM code happens to be at the end? Or do we just not care >> here? > > Actually we can jump +/- 32MB (26 bits). I believe that the linker > inserts trampolines if the branch target is more than 32MB away, so it > should still work if the kernel is really large and the KVM code > happens to be at the end. > > Stephen Rothwell has been asking me about this patch. He wants it in > (or something like it) so that he can get his daily linux-next powerpc > allyesconfig builds to stop failing. Yup, currently running autotest with this and other patches applied. Will send out a pullreq soon. Alex > > Paul. > -- > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 41b02c7..29ddd8b 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -427,16 +427,6 @@ slb_miss_user_pseries: b . /* prevent spec. execution */ #endif /* __DISABLED__ */ -/* KVM's trampoline code needs to be close to the interrupt handlers */ - -#ifdef CONFIG_KVM_BOOK3S_64_HANDLER -#ifdef CONFIG_KVM_BOOK3S_PR -#include "../kvm/book3s_rmhandlers.S" -#else -#include "../kvm/book3s_hv_rmhandlers.S" -#endif -#endif - .align 7 .globl __end_interrupts __end_interrupts: diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile index 08428e2..e161680 100644 --- a/arch/powerpc/kvm/Makefile +++ b/arch/powerpc/kvm/Makefile @@ -49,12 +49,15 @@ kvm-book3s_64-objs-$(CONFIG_KVM_BOOK3S_64_PR) := \ book3s_64_mmu_host.o \ book3s_64_mmu.o \ book3s_32_mmu.o +kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_PR) := \ + book3s_rmhandlers.o kvm-book3s_64-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \ book3s_hv.o \ book3s_hv_interrupts.o \ book3s_64_mmu_hv.o kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \ + book3s_hv_rmhandlers.o \ book3s_hv_rm_mmu.o \ book3s_64_vio_hv.o \ book3s_hv_builtin.o diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 6dd3358..543ee50 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -20,7 +20,10 @@ #include <asm/ppc_asm.h> #include <asm/kvm_asm.h> #include <asm/reg.h> +#include <asm/mmu.h> #include <asm/page.h> +#include <asm/ptrace.h> +#include <asm/hvcall.h> #include <asm/asm-offsets.h> #include <asm/exception-64s.h> diff --git a/arch/powerpc/kvm/book3s_rmhandlers.S b/arch/powerpc/kvm/book3s_rmhandlers.S index c1f877c..5ee66ed 100644 --- a/arch/powerpc/kvm/book3s_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_rmhandlers.S @@ -20,6 +20,7 @@ #include <asm/ppc_asm.h> #include <asm/kvm_asm.h> #include <asm/reg.h> +#include <asm/mmu.h> #include <asm/page.h> #include <asm/asm-offsets.h> @@ -39,6 +40,7 @@ #define MSR_NOIRQ MSR_KERNEL & ~(MSR_IR | MSR_DR) #define FUNC(name) GLUE(.,name) + .globl kvmppc_skip_interrupt kvmppc_skip_interrupt: /* * Here all GPRs are unchanged from when the interrupt happened @@ -51,6 +53,7 @@ kvmppc_skip_interrupt: rfid b . + .globl kvmppc_skip_Hinterrupt kvmppc_skip_Hinterrupt: /* * Here all GPRs are unchanged from when the interrupt happened
This makes arch/powerpc/kvm/book3s_rmhandlers.S and arch/powerpc/kvm/book3s_hv_rmhandlers.S be assembled as separate compilation units rather than having them #included in arch/powerpc/kernel/exceptions-64s.S. We no longer have any conditional branches between the exception prologs in exceptions-64s.S and the KVM handlers, so there is no need to keep their contents close together in the vmlinux image. In their current location, they are using up part of the limited space between the first-level interrupt handlers and the firmware NMI data area at offset 0x7000, and with some kernel configurations this area will overflow (e.g. allyesconfig), leading to an "attempt to .org backwards" error when compiling exceptions-64s.S. Moving them out requires that we add some #includes that the book3s_{,hv_}rmhandlers.S code was previously getting implicitly via exceptions-64s.S. Signed-off-by: Paul Mackerras <paulus@samba.org> --- arch/powerpc/kernel/exceptions-64s.S | 10 ---------- arch/powerpc/kvm/Makefile | 3 +++ arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 +++ arch/powerpc/kvm/book3s_rmhandlers.S | 3 +++ 4 files changed, 9 insertions(+), 10 deletions(-)