Re: [PATCH 1/2] LoongArch: Initialise unused Direct Map Windows

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On Fri, Jun 14, 2024 at 10:18 AM Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> wrote:
>
>
>
> 在2024年6月14日六月 上午3:13,Huacai Chen写道:
> > Hi, Jiaxun,
> >
> > On Fri, Jun 14, 2024 at 12:41 AM Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> wrote:
> >>
> >> DMW 2 & 3 are unused by kernel, however firmware may leave
> >> garbage in them and interfere kernel's address mapping.
> >>
> >> Clear them as necessary.
> > I think the current status is as expected, we don't want kernel access
> > to non-8000 and non-9000 addresses. And low-end chips may have only
> > two DMWs.
>
> I see, I'll remove U-Boot's dependency to DMW 2 and 3 then.
I was told that DMW2&3 are probably exist (but cannot used for
instruction fetch), so I applied this patch and implement DMW-based
ioremap_wc().

https://github.com/chenhuacai/linux/commit/fa9f4109bf19a19736877d01e3e3529756a96095


Huacai

>
> Thanks
> - Jiaxun
>
> >
> > Huacai
> >
> >
> > Huacai
> >
> >>
> >> Cc: stable@xxxxxxxxxxxxxxx
> >> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
> >> ---
> >>  arch/loongarch/include/asm/loongarch.h   |  4 ++++
> >>  arch/loongarch/include/asm/stackframe.h  | 11 +++++++++++
> >>  arch/loongarch/kernel/head.S             | 12 ++----------
> >>  arch/loongarch/power/suspend_asm.S       |  6 +-----
> >>  drivers/firmware/efi/libstub/loongarch.c |  2 ++
> >>  5 files changed, 20 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
> >> index eb09adda54b7..3720096efcf9 100644
> >> --- a/arch/loongarch/include/asm/loongarch.h
> >> +++ b/arch/loongarch/include/asm/loongarch.h
> >> @@ -889,6 +889,10 @@
> >>  #define CSR_DMW1_BASE          (CSR_DMW1_VSEG << DMW_PABITS)
> >>  #define CSR_DMW1_INIT          (CSR_DMW1_BASE | CSR_DMW1_MAT | CSR_DMW1_PLV0)
> >>
> >> +/* Direct Map window 2/3 - unused */
> >> +#define CSR_DMW2_INIT          0
> >> +#define CSR_DMW3_INIT          0
> >> +
> >>  /* Performance Counter registers */
> >>  #define LOONGARCH_CSR_PERFCTRL0                0x200   /* 32 perf event 0 config */
> >>  #define LOONGARCH_CSR_PERFCNTR0                0x201   /* 64 perf event 0 count value */
> >> diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
> >> index d9eafd3ee3d1..10c5dcf56bc7 100644
> >> --- a/arch/loongarch/include/asm/stackframe.h
> >> +++ b/arch/loongarch/include/asm/stackframe.h
> >> @@ -38,6 +38,17 @@
> >>         cfi_restore \reg \offset \docfi
> >>         .endm
> >>
> >> +       .macro SETUP_DMWS temp1
> >> +       li.d    \temp1, CSR_DMW0_INIT
> >> +       csrwr   \temp1, LOONGARCH_CSR_DMWIN0
> >> +       li.d    \temp1, CSR_DMW1_INIT
> >> +       csrwr   \temp1, LOONGARCH_CSR_DMWIN1
> >> +       li.d    \temp1, CSR_DMW2_INIT
> >> +       csrwr   \temp1, LOONGARCH_CSR_DMWIN2
> >> +       li.d    \temp1, CSR_DMW3_INIT
> >> +       csrwr   \temp1, LOONGARCH_CSR_DMWIN3
> >> +       .endm
> >> +
> >>  /* Jump to the runtime virtual address. */
> >>         .macro JUMP_VIRT_ADDR temp1 temp2
> >>         li.d    \temp1, CACHE_BASE
> >> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> >> index 4677ea8fa8e9..1a71fc09bfd6 100644
> >> --- a/arch/loongarch/kernel/head.S
> >> +++ b/arch/loongarch/kernel/head.S
> >> @@ -44,11 +44,7 @@ SYM_DATA(kernel_fsize, .long _kernel_fsize);
> >>  SYM_CODE_START(kernel_entry)                   # kernel entry point
> >>
> >>         /* Config direct window and set PG */
> >> -       li.d            t0, CSR_DMW0_INIT       # UC, PLV0, 0x8000 xxxx xxxx xxxx
> >> -       csrwr           t0, LOONGARCH_CSR_DMWIN0
> >> -       li.d            t0, CSR_DMW1_INIT       # CA, PLV0, 0x9000 xxxx xxxx xxxx
> >> -       csrwr           t0, LOONGARCH_CSR_DMWIN1
> >> -
> >> +       SETUP_DMWS      t0
> >>         JUMP_VIRT_ADDR  t0, t1
> >>
> >>         /* Enable PG */
> >> @@ -124,11 +120,7 @@ SYM_CODE_END(kernel_entry)
> >>   * function after setting up the stack and tp registers.
> >>   */
> >>  SYM_CODE_START(smpboot_entry)
> >> -       li.d            t0, CSR_DMW0_INIT       # UC, PLV0
> >> -       csrwr           t0, LOONGARCH_CSR_DMWIN0
> >> -       li.d            t0, CSR_DMW1_INIT       # CA, PLV0
> >> -       csrwr           t0, LOONGARCH_CSR_DMWIN1
> >> -
> >> +       SETUP_DMWS      t0
> >>         JUMP_VIRT_ADDR  t0, t1
> >>
> >>  #ifdef CONFIG_PAGE_SIZE_4KB
> >> diff --git a/arch/loongarch/power/suspend_asm.S b/arch/loongarch/power/suspend_asm.S
> >> index e2fc3b4e31f0..6fdd74eb219b 100644
> >> --- a/arch/loongarch/power/suspend_asm.S
> >> +++ b/arch/loongarch/power/suspend_asm.S
> >> @@ -73,11 +73,7 @@ SYM_FUNC_START(loongarch_suspend_enter)
> >>          * Reload all of the registers and return.
> >>          */
> >>  SYM_INNER_LABEL(loongarch_wakeup_start, SYM_L_GLOBAL)
> >> -       li.d            t0, CSR_DMW0_INIT       # UC, PLV0
> >> -       csrwr           t0, LOONGARCH_CSR_DMWIN0
> >> -       li.d            t0, CSR_DMW1_INIT       # CA, PLV0
> >> -       csrwr           t0, LOONGARCH_CSR_DMWIN1
> >> -
> >> +       SETUP_DMWS      t0
> >>         JUMP_VIRT_ADDR  t0, t1
> >>
> >>         /* Enable PG */
> >> diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
> >> index d0ef93551c44..3782d0a187d1 100644
> >> --- a/drivers/firmware/efi/libstub/loongarch.c
> >> +++ b/drivers/firmware/efi/libstub/loongarch.c
> >> @@ -74,6 +74,8 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
> >>         /* Config Direct Mapping */
> >>         csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
> >>         csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
> >> +       csr_write64(CSR_DMW2_INIT, LOONGARCH_CSR_DMWIN2);
> >> +       csr_write64(CSR_DMW3_INIT, LOONGARCH_CSR_DMWIN3);
> >>
> >>         real_kernel_entry = (void *)kernel_entry_address(kernel_addr, image);
> >>
> >>
> >> --
> >> 2.43.0
> >>
> >>
>
> --
> - Jiaxun
>





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