Re: [PATCH 6.6 430/638] powerpc/ps3: Fix lv1 hcall assembly for ELFv2 calling convention

Michael Ellerman
2024-03-26T04:36:19Z

Sasha Levin <sashal@kernel.org> writes:
> From: Nicholas Piggin <npiggin@gmail.com>
>
> [ Upstream commit 6735fef14c1f089ae43fd6d43add818b7ff682a8 ]
>
> Stack-passed parameters begin at a different offset in the caller's
> stack in the ELFv2 ABI.
>
> Reported-by: Geoff Levand <geoff@infradead.org>
> Fixes: 8c5fa3b5c4df ("powerpc/64: Make ELFv2 the default for big-endian builds")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> Tested-by: Geoff Levand <geoff@infradead.org>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Link: https://msgid.link/20231227072405.63751-2-npiggin@gmail.com
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> arch/powerpc/include/asm/ppc_asm.h | 6 ++++--
> arch/powerpc/platforms/ps3/hvcall.S | 18 +++++++++---------
> 2 files changed, 13 insertions(+), 11 deletions(-)

This commit is OK on its own, but it doesn't have any effect unless the
full series up to 914d081ead11 ("Revert "powerpc/ps3_defconfig: Disable
PPC64_BIG_ENDIAN_ELF_ABI_V2"") is backported.

I don't think the full series warrants backporting, it's really enabling
a new feature (ELFv2 build for ps3).

So IMHO please drop this patch from 6.6, 6.7, 6.8.

cheers

> diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
> index e7792aa135105..041ee25955205 100644
> --- a/arch/powerpc/include/asm/ppc_asm.h
> +++ b/arch/powerpc/include/asm/ppc_asm.h
> @@ -201,11 +201,13 @@
>
> #ifdef CONFIG_PPC64_ELF_ABI_V2
> #define STK_GOT 24
> -#define __STK_PARAM(i) (32 + ((i)-3)*8)
> +#define STK_PARAM_AREA 32
> #else
> #define STK_GOT 40
> -#define __STK_PARAM(i) (48 + ((i)-3)*8)
> +#define STK_PARAM_AREA 48
> #endif
> +
> +#define __STK_PARAM(i) (STK_PARAM_AREA + ((i)-3)*8)
> #define STK_PARAM(i) __STK_PARAM(__REG_##i)
>
> #ifdef CONFIG_PPC64_ELF_ABI_V2
> diff --git a/arch/powerpc/platforms/ps3/hvcall.S b/arch/powerpc/platforms/ps3/hvcall.S
> index 509e30ad01bb4..59ea569debf47 100644
> --- a/arch/powerpc/platforms/ps3/hvcall.S
> +++ b/arch/powerpc/platforms/ps3/hvcall.S
> @@ -714,7 +714,7 @@ _GLOBAL(_##API_NAME) \
> std r4, 0(r11); \
> ld r11, -16(r1); \
> std r5, 0(r11); \
> - ld r11, 48+8*8(r1); \
> + ld r11, STK_PARAM_AREA+8*8(r1); \
> std r6, 0(r11); \
> \
> ld r0, 16(r1); \
> @@ -746,22 +746,22 @@ _GLOBAL(_##API_NAME) \
> mflr r0; \
> std r0, 16(r1); \
> \
> - std r10, 48+8*7(r1); \
> + std r10, STK_PARAM_AREA+8*7(r1); \
> \
> li r11, API_NUMBER; \
> lv1call; \
> \
> - ld r11, 48+8*7(r1); \
> + ld r11, STK_PARAM_AREA+8*7(r1); \
> std r4, 0(r11); \
> - ld r11, 48+8*8(r1); \
> + ld r11, STK_PARAM_AREA+8*8(r1); \
> std r5, 0(r11); \
> - ld r11, 48+8*9(r1); \
> + ld r11, STK_PARAM_AREA+8*9(r1); \
> std r6, 0(r11); \
> - ld r11, 48+8*10(r1); \
> + ld r11, STK_PARAM_AREA+8*10(r1); \
> std r7, 0(r11); \
> - ld r11, 48+8*11(r1); \
> + ld r11, STK_PARAM_AREA+8*11(r1); \
> std r8, 0(r11); \
> - ld r11, 48+8*12(r1); \
> + ld r11, STK_PARAM_AREA+8*12(r1); \
> std r9, 0(r11); \
> \
> ld r0, 16(r1); \
> @@ -777,7 +777,7 @@ _GLOBAL(_##API_NAME) \
> li r11, API_NUMBER; \
> lv1call; \
> \
> - ld r11, 48+8*8(r1); \
> + ld r11, STK_PARAM_AREA+8*8(r1); \
> std r4, 0(r11); \
> \
> ld r0, 16(r1); \
> --
> 2.43.0