| Message ID | 1450673050-12101-1-git-send-email-ynorov@caviumnetworks.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Dec 21, 2015 at 07:44:10AM +0300, Yury Norov wrote: > Kernel option COMPAT defines the ability of executing aarch32 binaries. > Some platforms does not support aarch32 mode, and so cannot execute that > binaries. But we cannot just disable COMPAT for them because the same > kernel binary may be used by multiple platforms. > > In this patch, system_supports_aarch32_el0() is introduced to detect > aarch32 support at run-time. > > v4: use new CPU Feature API. > v5: use cpuid_feature_extract_field. > > Signed-off-by: Yury Norov <ynorov@caviumnetworks.com> > --- > arch/arm64/include/asm/cpufeature.h | 7 +++++++ > arch/arm64/include/asm/elf.h | 6 ++++-- > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > index 8f271b8..bcb0dbe 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -184,6 +184,13 @@ static inline bool system_supports_mixed_endian_el0(void) > return id_aa64mmfr0_mixed_endian_el0(read_system_reg(SYS_ID_AA64MMFR0_EL1)); > } > > +static inline bool system_supports_aarch32_el0(void) > +{ > + u64 pfr0 = read_system_reg(SYS_ID_AA64PFR0_EL1); > + return cpuid_feature_extract_field(pfr0, ID_AA64PFR0_EL0_SHIFT) > + != ID_AA64PFR0_EL0_64BIT_ONLY; > +} Suzuki already suggested to hook this into the existing arm64_features[] array: http://lkml.kernel.org/g/56748437.2040905@arm.com > +#define compat_elf_check_arch(x) (system_supports_aarch32_el0() \ > + && ((x)->e_machine == EM_ARM) \ > + && ((x)->e_flags & EF_ARM_EABI_MASK)) And here use something like cpus_have_cap(ARM64_HAS_32BIT_EL0). And a nitpick: please use the same convention for placing the "&&" operator like in the rest of the file, i.e. on the previous line (similarly for "!=" etc.)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 8f271b8..bcb0dbe 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -184,6 +184,13 @@ static inline bool system_supports_mixed_endian_el0(void) return id_aa64mmfr0_mixed_endian_el0(read_system_reg(SYS_ID_AA64MMFR0_EL1)); } +static inline bool system_supports_aarch32_el0(void) +{ + u64 pfr0 = read_system_reg(SYS_ID_AA64PFR0_EL1); + return cpuid_feature_extract_field(pfr0, ID_AA64PFR0_EL0_SHIFT) + != ID_AA64PFR0_EL0_64BIT_ONLY; +} + #endif /* __ASSEMBLY__ */ #endif diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index faad6df..99ec9ac 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -21,6 +21,7 @@ /* * ELF register definitions.. */ +#include <asm/cpufeature.h> #include <asm/ptrace.h> #include <asm/user.h> @@ -173,8 +174,9 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG]; /* AArch32 EABI. */ #define EF_ARM_EABI_MASK 0xff000000 -#define compat_elf_check_arch(x) (((x)->e_machine == EM_ARM) && \ - ((x)->e_flags & EF_ARM_EABI_MASK)) +#define compat_elf_check_arch(x) (system_supports_aarch32_el0() \ + && ((x)->e_machine == EM_ARM) \ + && ((x)->e_flags & EF_ARM_EABI_MASK)) #define compat_start_thread compat_start_thread #define COMPAT_SET_PERSONALITY(ex) set_thread_flag(TIF_32BIT);
Kernel option COMPAT defines the ability of executing aarch32 binaries. Some platforms does not support aarch32 mode, and so cannot execute that binaries. But we cannot just disable COMPAT for them because the same kernel binary may be used by multiple platforms. In this patch, system_supports_aarch32_el0() is introduced to detect aarch32 support at run-time. v4: use new CPU Feature API. v5: use cpuid_feature_extract_field. Signed-off-by: Yury Norov <ynorov@caviumnetworks.com> --- arch/arm64/include/asm/cpufeature.h | 7 +++++++ arch/arm64/include/asm/elf.h | 6 ++++-- 2 files changed, 11 insertions(+), 2 deletions(-)