On 29/09/2023 12:19 am, Shawn Anastasio wrote: > On Power, the exception vectors must lie at a fixed address, depending > on the state of the Alternate Interrupt Location (AIL) field of the > Logical Partition Control Register (LPCR). Create a .text.exceptions > section in the linker script at an address suitable for AIL=3 plus an > accompanying assertion to pave the way for implementing exception > support.
Thanks - this is a perfect level of detail as far as I'm concerned as a PPC novice. > > Signed-off-by: Shawn Anastasio <[email protected]> > --- > xen/arch/ppc/include/asm/config.h | 3 +++ > xen/arch/ppc/xen.lds.S | 7 +++++++ > 2 files changed, 10 insertions(+) > > diff --git a/xen/arch/ppc/include/asm/config.h > b/xen/arch/ppc/include/asm/config.h > index a11a09c570..e012b75beb 100644 > --- a/xen/arch/ppc/include/asm/config.h > +++ b/xen/arch/ppc/include/asm/config.h > @@ -42,6 +42,9 @@ > > #define XEN_VIRT_START _AC(0xc000000000000000, UL) > > +/* Fixed address for start of the section containing exception vectors */ > +#define EXCEPTION_VECTORS_START _AC(0xc000000000000100, UL) The patch looks fine, but a PPC question. Does AIL=3 really mean a hard coded address at 0xc000000000000100 ? Or is it +0x100 from something else that happens to be programmed to XEN_VIRT_START ? > + > #define VMAP_VIRT_START (XEN_VIRT_START + GB(1)) > #define VMAP_VIRT_SIZE GB(1) > > diff --git a/xen/arch/ppc/xen.lds.S b/xen/arch/ppc/xen.lds.S > index 9e46035155..9e888d7383 100644 > --- a/xen/arch/ppc/xen.lds.S > +++ b/xen/arch/ppc/xen.lds.S > @@ -24,6 +24,10 @@ SECTIONS > _stext = .; /* Text section */ > *(.text.header) > > + . = ALIGN(256); > + _stext_exceptions = .; If this is really only used for the linker assertion, then it wants to be HIDDEN(_stext_exceptions = .); otherwise the debugging symbols will have _stext_exceptions typically hiding exc_sysreset in the disassembly and symbol table. > + *(.text.exceptions) > + > *(.text.cold) > *(.text.unlikely .text.*_unlikely .text.unlikely.*) > > @@ -184,3 +188,6 @@ ASSERT(IS_ALIGNED(__bss_end, POINTER_ALIGN), > "__bss_end is misaligned") > > ASSERT(!SIZEOF(.got), ".got non-empty") > ASSERT(!SIZEOF(.got.plt), ".got.plt non-empty") > + > +ASSERT(_stext_exceptions == EXCEPTION_VECTORS_START, \ > + ".text.exceptions not at expected location -- .text.header too big?"); No need for ; at the end, and no need for \ either. As I said for patch 1, we're now at 4.18-rc1. Does this need to be included now, or wait for 4.19? There's something to be said for having a basic exception handler, but it is technically a new feature... ~Andrew
