| Message ID | 2785518800dce64fafb3096480a5ae4c4e026bcb.1678970065.git.oleksii.kurochko@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | deal with GOT stuff for RISC-V | expand |
On 16.03.2023 14:22, Oleksii Kurochko wrote: > The patch is needed to keep all address of cpu0_boot_stack > PC-relative. > > Pseudoinstruction 'la' can be transformed to 'auipc/addi' or > 'auipc/l{w|d}'. It depends on the .option directive: nopic and pic > or compiler flags. > > Right now, 'la' transforms to 'auipc/l{w|d}', which in case of > cpu0_boot_stack[] will lead to the usage of _GLOBAL_OFFSET_TABLE_ > where all addresses will be without counting that it might happen > that linker address != load address ( so addresses inside got > sections will be relative to linker time ). > > It happens becuase the compiler from riscv64 docker compiled with > --enable-default-pie: > [user@49295ae49cbe build]$ riscv64-linux-gnu-gcc -v > Using built-in specs. > COLLECT_GCC=riscv64-linux-gnu-gcc > COLLECT_LTO_WRAPPER=/usr/lib/gcc/riscv64-linux-gnu/12.2.0/lto-wrapper > Target: riscv64-linux-gnu > Configured with: /build/riscv64-linux-gnu-gcc/src/gcc-12.2.0/configure > --prefix=/usr --program-prefix=riscv64-linux-gnu- --with-local- > prefix=/usr/riscv64-linux-gnu --with-sysroot=/usr/riscv64-linux-gnu -- > with-build-sysroot=/usr/riscv64-linux-gnu --libdir=/usr/lib -- > libexecdir=/usr/lib --target=riscv64-linux-gnu --host=x86_64-pc-linux- > gnu --build=x86_64-pc-linux-gnu --with-system-zlib --with-isl --with- > linker-hash-style=gnu --disable-nls --disable-libunwind-exceptions -- > disable-libstdcxx-pch --disable-libssp --disable-multilib --disable- > werror --enable-languages=c,c++ --enable-shared --enable-threads=posix > --enable-__cxa_atexit --enable-clocale=gnu --enable-gnu-unique-object - > -enable-linker-build-id --enable-lto --enable-plugin --enable-install- > libiberty --enable-gnu-indirect-function --enable-default-pie --enable- > checking=release > Thread model: posix > Supported LTO compression algorithms: zlib zstd > gcc version 12.2.0 (GCC) > > Looking at gcc spec file for the RISC-V architecture: > [user@49295ae49cbe build]$ riscv64-linux-gnu-gcc -dumpspecs | grep -i > pic > --traditional-format %(subtarget_asm_debugging_spec) %{fno-pie|fno- > PIE|fno-pic|fno-PIC:;:-fpic} %{march=*} %{mabi=*} %{mno-relax} %{mbig- > endian} %{mlittle-endian} %(subtarget_asm_spec)%{misa-spec=*} > which means that -fpic is enabled if none of the following options are > present on the command line: > -fno-pie > -fno-PIE > -fno-pic > -fno-PIC > > That's the reasons why 'la' is transformed to 'aupic/l{w|d} GOT' and > not be dependent on the toolchain used. > > Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> There may also want to be Suggested-by to both Andrew and me. Jan
On Thu, Mar 16, 2023 at 11:22 PM Oleksii Kurochko <oleksii.kurochko@gmail.com> wrote: > > The patch is needed to keep all address of cpu0_boot_stack > PC-relative. > > Pseudoinstruction 'la' can be transformed to 'auipc/addi' or > 'auipc/l{w|d}'. It depends on the .option directive: nopic and pic > or compiler flags. > > Right now, 'la' transforms to 'auipc/l{w|d}', which in case of > cpu0_boot_stack[] will lead to the usage of _GLOBAL_OFFSET_TABLE_ > where all addresses will be without counting that it might happen > that linker address != load address ( so addresses inside got > sections will be relative to linker time ). > > It happens becuase the compiler from riscv64 docker compiled with > --enable-default-pie: > [user@49295ae49cbe build]$ riscv64-linux-gnu-gcc -v > Using built-in specs. > COLLECT_GCC=riscv64-linux-gnu-gcc > COLLECT_LTO_WRAPPER=/usr/lib/gcc/riscv64-linux-gnu/12.2.0/lto-wrapper > Target: riscv64-linux-gnu > Configured with: /build/riscv64-linux-gnu-gcc/src/gcc-12.2.0/configure > --prefix=/usr --program-prefix=riscv64-linux-gnu- --with-local- > prefix=/usr/riscv64-linux-gnu --with-sysroot=/usr/riscv64-linux-gnu -- > with-build-sysroot=/usr/riscv64-linux-gnu --libdir=/usr/lib -- > libexecdir=/usr/lib --target=riscv64-linux-gnu --host=x86_64-pc-linux- > gnu --build=x86_64-pc-linux-gnu --with-system-zlib --with-isl --with- > linker-hash-style=gnu --disable-nls --disable-libunwind-exceptions -- > disable-libstdcxx-pch --disable-libssp --disable-multilib --disable- > werror --enable-languages=c,c++ --enable-shared --enable-threads=posix > --enable-__cxa_atexit --enable-clocale=gnu --enable-gnu-unique-object - > -enable-linker-build-id --enable-lto --enable-plugin --enable-install- > libiberty --enable-gnu-indirect-function --enable-default-pie --enable- > checking=release > Thread model: posix > Supported LTO compression algorithms: zlib zstd > gcc version 12.2.0 (GCC) > > Looking at gcc spec file for the RISC-V architecture: > [user@49295ae49cbe build]$ riscv64-linux-gnu-gcc -dumpspecs | grep -i > pic > --traditional-format %(subtarget_asm_debugging_spec) %{fno-pie|fno- > PIE|fno-pic|fno-PIC:;:-fpic} %{march=*} %{mabi=*} %{mno-relax} %{mbig- > endian} %{mlittle-endian} %(subtarget_asm_spec)%{misa-spec=*} > which means that -fpic is enabled if none of the following options are > present on the command line: > -fno-pie > -fno-PIE > -fno-pic > -fno-PIC > > That's the reasons why 'la' is transformed to 'aupic/l{w|d} GOT' and > not be dependent on the toolchain used. > > Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com> Acked-by: Alistair Francis <alistair.francis@wdc.com> Alistair > --- > Changes in V2: > * instead of changing 'la' to 'lla' to keep cpu0_boot_stack PC-relative > it was updated CFLAGS with EMBEDDED_EXTRA_CFLAGS which contains > -fno-PIE thereby 'la' will be transformed to 'auipc/addi' without > GOT usage. > * update the commit message with additional details. > --- > xen/arch/riscv/arch.mk | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/xen/arch/riscv/arch.mk b/xen/arch/riscv/arch.mk > index 45fe858ee0..7448f759b4 100644 > --- a/xen/arch/riscv/arch.mk > +++ b/xen/arch/riscv/arch.mk > @@ -1,6 +1,8 @@ > ######################################## > # RISCV-specific definitions > > +$(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS)) > + > CFLAGS-$(CONFIG_RISCV_64) += -mabi=lp64 > > riscv-march-$(CONFIG_RISCV_ISA_RV64G) := rv64g > -- > 2.39.2 > >
diff --git a/xen/arch/riscv/arch.mk b/xen/arch/riscv/arch.mk index 45fe858ee0..7448f759b4 100644 --- a/xen/arch/riscv/arch.mk +++ b/xen/arch/riscv/arch.mk @@ -1,6 +1,8 @@ ######################################## # RISCV-specific definitions +$(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS)) + CFLAGS-$(CONFIG_RISCV_64) += -mabi=lp64 riscv-march-$(CONFIG_RISCV_ISA_RV64G) := rv64g
The patch is needed to keep all address of cpu0_boot_stack PC-relative. Pseudoinstruction 'la' can be transformed to 'auipc/addi' or 'auipc/l{w|d}'. It depends on the .option directive: nopic and pic or compiler flags. Right now, 'la' transforms to 'auipc/l{w|d}', which in case of cpu0_boot_stack[] will lead to the usage of _GLOBAL_OFFSET_TABLE_ where all addresses will be without counting that it might happen that linker address != load address ( so addresses inside got sections will be relative to linker time ). It happens becuase the compiler from riscv64 docker compiled with --enable-default-pie: [user@49295ae49cbe build]$ riscv64-linux-gnu-gcc -v Using built-in specs. COLLECT_GCC=riscv64-linux-gnu-gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/riscv64-linux-gnu/12.2.0/lto-wrapper Target: riscv64-linux-gnu Configured with: /build/riscv64-linux-gnu-gcc/src/gcc-12.2.0/configure --prefix=/usr --program-prefix=riscv64-linux-gnu- --with-local- prefix=/usr/riscv64-linux-gnu --with-sysroot=/usr/riscv64-linux-gnu -- with-build-sysroot=/usr/riscv64-linux-gnu --libdir=/usr/lib -- libexecdir=/usr/lib --target=riscv64-linux-gnu --host=x86_64-pc-linux- gnu --build=x86_64-pc-linux-gnu --with-system-zlib --with-isl --with- linker-hash-style=gnu --disable-nls --disable-libunwind-exceptions -- disable-libstdcxx-pch --disable-libssp --disable-multilib --disable- werror --enable-languages=c,c++ --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-gnu-unique-object - -enable-linker-build-id --enable-lto --enable-plugin --enable-install- libiberty --enable-gnu-indirect-function --enable-default-pie --enable- checking=release Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 12.2.0 (GCC) Looking at gcc spec file for the RISC-V architecture: [user@49295ae49cbe build]$ riscv64-linux-gnu-gcc -dumpspecs | grep -i pic --traditional-format %(subtarget_asm_debugging_spec) %{fno-pie|fno- PIE|fno-pic|fno-PIC:;:-fpic} %{march=*} %{mabi=*} %{mno-relax} %{mbig- endian} %{mlittle-endian} %(subtarget_asm_spec)%{misa-spec=*} which means that -fpic is enabled if none of the following options are present on the command line: -fno-pie -fno-PIE -fno-pic -fno-PIC That's the reasons why 'la' is transformed to 'aupic/l{w|d} GOT' and not be dependent on the toolchain used. Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com> --- Changes in V2: * instead of changing 'la' to 'lla' to keep cpu0_boot_stack PC-relative it was updated CFLAGS with EMBEDDED_EXTRA_CFLAGS which contains -fno-PIE thereby 'la' will be transformed to 'auipc/addi' without GOT usage. * update the commit message with additional details. --- xen/arch/riscv/arch.mk | 2 ++ 1 file changed, 2 insertions(+)