Le 04/11/2022 à 18:27, Andrew Donnellan a écrit :
> When CONFIG_VMAP_STACK is enabled, we set THREAD_SIZE to be at least the
> size of a page.
>
> There's a few bits of assembly in the book3s64 code that use THREAD_SIZE in
> immediate mode instructions, which can only take an operand of up to 16
> bits signed, which isn't quite large enough.
>
> Fix these spots to use a scratch register or use two immediate mode
> instructions instead, so we can later enable VMAP_STACK.
>
> Signed-off-by: Andrew Donnellan <a...@linux.ibm.com>
> ---
> arch/powerpc/include/asm/asm-compat.h | 2 ++
> arch/powerpc/kernel/entry_64.S | 4 +++-
> arch/powerpc/kernel/irq.c | 8 ++++++--
> arch/powerpc/kernel/misc_64.S | 4 +++-
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 ++-
> 5 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/asm-compat.h
> b/arch/powerpc/include/asm/asm-compat.h
> index 2bc53c646ccd..30dd7813bf3b 100644
> --- a/arch/powerpc/include/asm/asm-compat.h
> +++ b/arch/powerpc/include/asm/asm-compat.h
> @@ -11,6 +11,7 @@
> #define PPC_LL stringify_in_c(ld)
> #define PPC_STL stringify_in_c(std)
> #define PPC_STLU stringify_in_c(stdu)
> +#define PPC_STLUX stringify_in_c(stdux)
> #define PPC_LCMPI stringify_in_c(cmpdi)
> #define PPC_LCMPLI stringify_in_c(cmpldi)
> #define PPC_LCMP stringify_in_c(cmpd)
> @@ -45,6 +46,7 @@
> #define PPC_LL stringify_in_c(lwz)
> #define PPC_STL stringify_in_c(stw)
> #define PPC_STLU stringify_in_c(stwu)
> +#define PPC_STLUX stringify_in_c(stwux)
> #define PPC_LCMPI stringify_in_c(cmpwi)
> #define PPC_LCMPLI stringify_in_c(cmplwi)
> #define PPC_LCMP stringify_in_c(cmpw)
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index 3e2e37e6ecab..af25db6e0205 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -238,7 +238,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
> /* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
> because we don't need to leave the 288-byte ABI gap at the
> top of the kernel stack. */
> - addi r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE
> + li r9,0
> + ori r9,r9,THREAD_SIZE-SWITCH_FRAME_SIZE
> + add r7,r7,r9
So you assume THREAD_SIZE is never more than 64k ? Is that a valid
assumption ?
What about the below instead:
addis r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE@ha
addi r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE@l
>
> /*
> * PMU interrupts in radix may come in here. They will use r1, not
> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index 9ede61a5a469..098cf6adceec 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -204,7 +204,9 @@ static __always_inline void call_do_softirq(const void
> *sp)
> {
> /* Temporarily switch r1 to sp, call __do_softirq() then restore r1. */
> asm volatile (
> - PPC_STLU " %%r1, %[offset](%[sp]) ;"
> + "li %%r0, 0 ;"
> + "ori %%r0, %%r0, %[offset] ;"
Same, you assume offset to be max 64k, is that correct ?
What about
lis r0, offset@h
ori r0, r0, offset@l
> + PPC_STLUX " %%r1, %[sp], %%r0 ;"
> "mr %%r1, %[sp] ;"
> "bl %[callee] ;"
> PPC_LL " %%r1, 0(%%r1) ;"
> @@ -256,7 +258,9 @@ static __always_inline void call_do_irq(struct pt_regs
> *regs, void *sp)
>
> /* Temporarily switch r1 to sp, call __do_irq() then restore r1. */
> asm volatile (
> - PPC_STLU " %%r1, %[offset](%[sp]) ;"
> + "li %%r0, 0 ;"
> + "ori %%r0, %%r0, %[offset] ;"
> + PPC_STLUX " %%r1, %[sp], %%r0 ;"
Same
> "mr %%r4, %%r1 ;"
> "mr %%r1, %[sp] ;"
> "bl %[callee] ;"
> diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
> index 36184cada00b..ff71b98500a3 100644
> --- a/arch/powerpc/kernel/misc_64.S
> +++ b/arch/powerpc/kernel/misc_64.S
> @@ -384,7 +384,9 @@ _GLOBAL(kexec_sequence)
> std r0,16(r1)
>
> /* switch stacks to newstack -- &kexec_stack.stack */
> - stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
> + li r0,0
> + ori r0,r0,THREAD_SIZE-STACK_FRAME_OVERHEAD
> + stdux r1,r3,r0
Same
> mr r1,r3
>
> li r0,0
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 37f50861dd98..d05e3d324f4d 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -2686,7 +2686,8 @@ kvmppc_bad_host_intr:
> mr r9, r1
> std r1, PACAR1(r13)
> ld r1, PACAEMERGSP(r13)
> - subi r1, r1, THREAD_SIZE/2 + INT_FRAME_SIZE
> + subi r1, r1, THREAD_SIZE/2
> + subi r1, r1, INT_FRAME_SIZE
Same, what about
subis r1, r1, THREAD_SIZE/2 + INT_FRAME_SIZE@ha
subi r1, r1, THREAD_SIZE/2 + INT_FRAME_SIZE@l
> std r9, 0(r1)
> std r0, GPR0(r1)
> std r9, GPR1(r1)
