riscv: Memory type control for platforms with physical memory aliases

[PATCH 05/11] riscv: ptdump: Only show N and MT bits when enabled in the kernel

Posted by Samuel Holland 3 weeks, 1 day ago

When the Svnapot or Svpbmt extension is not implemented, the
corresponding page table bits are reserved, and must be zero. There is
no need to show them in the ptdump output.

When the Kconfig option for an extension is disabled, we assume it is
not implemented. In that case, the kernel may provide a fallback
definition for the fields, like how _PAGE_MTMASK is defined on riscv32.
Using those fallback definitions in ptdump would produce incorrect
results. To avoid this, hide the fields from the ptdump output.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---

 arch/riscv/mm/ptdump.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c
index 9d5f657a251b..58a7322e9a82 100644
--- a/arch/riscv/mm/ptdump.c
+++ b/arch/riscv/mm/ptdump.c
@@ -135,11 +135,13 @@ struct prot_bits {
 
 static const struct prot_bits pte_bits[] = {
 	{
-#ifdef CONFIG_64BIT
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
 		.mask = _PAGE_NAPOT,
 		.set = "N",
 		.clear = ".",
 	}, {
+#endif
+#ifdef CONFIG_RISCV_ISA_SVPBMT
 		.mask = _PAGE_MTMASK_SVPBMT,
 		.set = "MT(%s)",
 		.clear = "  ..  ",
@@ -215,7 +217,7 @@ static void dump_prot(struct pg_state *st)
 		if (val) {
 			if (pte_bits[i].mask == _PAGE_SOFT)
 				sprintf(s, pte_bits[i].set, val >> 8);
-#ifdef CONFIG_64BIT
+#ifdef CONFIG_RISCV_ISA_SVPBMT
 			else if (pte_bits[i].mask == _PAGE_MTMASK_SVPBMT) {
 				if (val == _PAGE_NOCACHE_SVPBMT)
 					sprintf(s, pte_bits[i].set, "NC");
-- 
2.45.1

Re: [PATCH 05/11] riscv: ptdump: Only show N and MT bits when enabled in the kernel

Posted by Alexandre Ghiti 2 weeks, 5 days ago

On 02/11/2024 01:07, Samuel Holland wrote:
> When the Svnapot or Svpbmt extension is not implemented, the
> corresponding page table bits are reserved, and must be zero. There is
> no need to show them in the ptdump output.
>
> When the Kconfig option for an extension is disabled, we assume it is
> not implemented. In that case, the kernel may provide a fallback
> definition for the fields, like how _PAGE_MTMASK is defined on riscv32.
> Using those fallback definitions in ptdump would produce incorrect
> results. To avoid this, hide the fields from the ptdump output.
>
> Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
> ---
>
>   arch/riscv/mm/ptdump.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c
> index 9d5f657a251b..58a7322e9a82 100644
> --- a/arch/riscv/mm/ptdump.c
> +++ b/arch/riscv/mm/ptdump.c
> @@ -135,11 +135,13 @@ struct prot_bits {
>   
>   static const struct prot_bits pte_bits[] = {
>   	{
> -#ifdef CONFIG_64BIT
> +#ifdef CONFIG_RISCV_ISA_SVNAPOT
>   		.mask = _PAGE_NAPOT,
>   		.set = "N",
>   		.clear = ".",
>   	}, {
> +#endif
> +#ifdef CONFIG_RISCV_ISA_SVPBMT
>   		.mask = _PAGE_MTMASK_SVPBMT,
>   		.set = "MT(%s)",
>   		.clear = "  ..  ",
> @@ -215,7 +217,7 @@ static void dump_prot(struct pg_state *st)
>   		if (val) {
>   			if (pte_bits[i].mask == _PAGE_SOFT)
>   				sprintf(s, pte_bits[i].set, val >> 8);
> -#ifdef CONFIG_64BIT
> +#ifdef CONFIG_RISCV_ISA_SVPBMT
>   			else if (pte_bits[i].mask == _PAGE_MTMASK_SVPBMT) {
>   				if (val == _PAGE_NOCACHE_SVPBMT)
>   					sprintf(s, pte_bits[i].set, "NC");


It makes sense so:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex