diff mbox series

[v4,2/2] riscv: Disable data start offset in flat binaries

Message ID 20210417011009.54569-3-damien.lemoal@wdc.com (mailing list archive)
State New, archived
Headers show
Series Fix binfmt_flat loader for RISC-V | expand

Commit Message

Damien Le Moal April 17, 2021, 1:10 a.m. UTC 
uclibc/gcc combined with elf2flt riscv linker file fully resolve the
PC relative __global_pointer$ value at compile time and do not generate
a relocation entry to set a correct value of the gp register at runtime.
As a result, if the flatbin loader offsets the start of the data
section, the relative position change between the text and data sections
compared to the compile time positions results in an incorrect gp value
being used. This causes flatbin executables to crash.

Avoid this problem by enabling CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
automatically when CONFIG_RISCV is enabled and CONFIG_MMU is disabled.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

Comments

Greg Ungerer April 17, 2021, 4:56 a.m. UTC | #1 
On 17/4/21 11:10 am, Damien Le Moal wrote:
> uclibc/gcc combined with elf2flt riscv linker file fully resolve the
> PC relative __global_pointer$ value at compile time and do not generate
> a relocation entry to set a correct value of the gp register at runtime.
> As a result, if the flatbin loader offsets the start of the data
> section, the relative position change between the text and data sections
> compared to the compile time positions results in an incorrect gp value
> being used. This causes flatbin executables to crash.
> 
> Avoid this problem by enabling CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
> automatically when CONFIG_RISCV is enabled and CONFIG_MMU is disabled.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

Acked-by: Greg Ungerer <gerg@linux-m68k.org>

Palmer do you want me to take this via my tree with 1/2 in the series,
or are you going to pick it up?

Regards
Greg


> ---
>   arch/riscv/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 4515a10c5d22..add528eb9235 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -33,6 +33,7 @@ config RISCV
>   	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
>   	select ARCH_WANT_FRAME_POINTERS
>   	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
> +	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
>   	select CLONE_BACKWARDS
>   	select CLINT_TIMER if !MMU
>   	select COMMON_CLK
>
diff mbox series

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 4515a10c5d22..add528eb9235 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -33,6 +33,7 @@  config RISCV
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
+	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
 	select CLONE_BACKWARDS
 	select CLINT_TIMER if !MMU
 	select COMMON_CLK