On Fri, Feb 02, 2024 at 01:02:39PM +1100, Michael Ellerman wrote: > Segher Boessenkool <seg...@kernel.crashing.org> writes: > > Hi! > > > > On Thu, Jan 25, 2024 at 05:12:28PM +0530, Naveen N Rao wrote: > >> diff --git a/arch/powerpc/kernel/interrupt_64.S > >> b/arch/powerpc/kernel/interrupt_64.S > >> index bd863702d812..5cf3758a19d3 100644 > >> --- a/arch/powerpc/kernel/interrupt_64.S > >> +++ b/arch/powerpc/kernel/interrupt_64.S > >> @@ -53,6 +53,7 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name) > >> ld r1,PACAKSAVE(r13) > >> std r10,0(r1) > >> std r11,_NIP(r1) > >> + std r11,_LINK(r1) > > > > Please add a comment here then, saying what the store is for? > > Yeah a comment would be good. > > Also the r11 value comes from LR, so it's not that we're storing the NIP > value into the LR slot, rather the value we store in NIP is from LR, see: > > EXC_VIRT_BEGIN(system_call_vectored, 0x3000, 0x1000) > /* SCV 0 */ > mr r9,r13 > GET_PACA(r13) > mflr r11 > ... > b system_call_vectored_common > > That's slightly pedantic, but I think it answers the question of why > it's OK to use the same value for NIP & LR, or why we don't have to do > mflr in system_call_vectored_common to get the actual LR value.
Thanks for clarifying that. I should have done a better job describing that in the commit log. I'll update that, add a comment here and send a v2. - Naveen
