RISC-V NOMMU flat binaries cannot tolerate a gap between the text and
data section as the toolchain fully resolves at compile time the PC
relative global pointer (__global_pointer$ value loaded in gp register).
Without a relocation entry provided, the flat bin loader cannot fix the
value if a gap is introduced and executables fail to run.
This series fixes this problem by allowing an architecture to request
the flat loader to suppress the gap between the text and data sections.
The first patch fixes binfmt_flat flat_load_file() using the new
configuration option CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP. The second
patch enables this option for RISCV NOMMU builds.
These patches do not change the binfmt_flat loader behavior for other
architectures.
Changes from v2:
* Updated distribution list
* Added Palmer ack-by tag
Changes from v1:
* Replace FLAT_TEXT_DATA_NO_GAP macro with
CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP config option (patch 1).
* Remove the addition of riscv/include/asm/flat.h and set
CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP for RISCV and !MMU
Damien Le Moal (2):
binfmt_flat: allow not offsetting data start
riscv: Disable text-data gap in flat binaries
arch/riscv/Kconfig | 1 +
fs/Kconfig.binfmt | 3 +++
fs/binfmt_flat.c | 21 +++++++++++++++------
3 files changed, 19 insertions(+), 6 deletions(-)
--
2.30.2
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 runtime gp value. As a result, if the
flatbin loader introduces a gap between the text and data sections, the
gp value becomes incorrect and prevent correct execution of a flatbin
executable.
Avoid this problem by enabling CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP
automatically when CONFIG_RISCV is enabled and CONFIG_MMU disabled.
Signed-off-by: Damien Le Moal <[email protected]>
Acked-by: Palmer Dabbelt <[email protected]>
---
arch/riscv/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0d0cf67359cb..6a85fbbd056e 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_TEXT_DATA_GAP if !MMU
select CLONE_BACKWARDS
select CLINT_TIMER if !MMU
select COMMON_CLK
--
2.30.2