From: "Eric W. Biederman" ebiederm@xmission.com
[ Upstream commit b029628be267cba3c7684ec684749fe3e4372398 ]
Richard Henderson richard.henderson@linaro.org writes[1]:
There was a Spec benchmark (I forget which) which was memory bound and ran twice as fast with 32-bit pointers.
I copied the idea from DEC to the ELF abi, but never did all the other work to allow the toolchain to take advantage.
Amusingly, a later Spec changed the benchmark data sets to not fit into a 32-bit address space, specifically because of this.
I expect one could delete the ELF bit and personality and no one would notice. Not even the 10 remaining Alpha users.
In [2] it was pointed out that parts of setarch weren't working properly on alpha because it has it's own SET_PERSONALITY implementation. In the discussion that followed Richard Henderson pointed out that the 32bit pointer support for alpha was never completed.
Fix this by removing alpha's 32bit pointer support.
As a bit of paranoia refuse to execute any alpha binaries that have the EF_ALPHA_32BIT flag set. Just in case someone somewhere has binaries that try to use alpha's 32bit pointer support.
Link: https://lkml.kernel.org/r/CAFXwXrkgu=4Qn-v1PjnOR4SG0oUb9LSa0g6QXpBq4ttm52pJO... [1] Link: https://lkml.kernel.org/r/20250103140148.370368-1-glaubitz@physik.fu-berlin.... [2] Signed-off-by: Eric W. Biederman ebiederm@xmission.com Reviewed-by: Richard Henderson richard.henderson@linaro.org Reviewed-by: Arnd Bergmann arnd@arndb.de Reviewed-by: John Paul Adrian Glaubitz glaubitz@physik.fu-berlin.de Tested-by: John Paul Adrian Glaubitz glaubitz@physik.fu-berlin.de Link: https://lore.kernel.org/r/87y0zfs26i.fsf_-_@email.froward.int.ebiederm.org Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/alpha/include/asm/elf.h | 6 +----- arch/alpha/include/asm/pgtable.h | 2 +- arch/alpha/include/asm/processor.h | 8 ++------ arch/alpha/kernel/osf_sys.c | 11 ++--------- 4 files changed, 6 insertions(+), 21 deletions(-)
diff --git a/arch/alpha/include/asm/elf.h b/arch/alpha/include/asm/elf.h index 4d7c46f50382e..50c82187e60ec 100644 --- a/arch/alpha/include/asm/elf.h +++ b/arch/alpha/include/asm/elf.h @@ -74,7 +74,7 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG]; /* * This is used to ensure we don't load something for the wrong architecture. */ -#define elf_check_arch(x) ((x)->e_machine == EM_ALPHA) +#define elf_check_arch(x) (((x)->e_machine == EM_ALPHA) && !((x)->e_flags & EF_ALPHA_32BIT))
/* * These are used to set parameters in the core dumps. @@ -137,10 +137,6 @@ extern int dump_elf_task(elf_greg_t *dest, struct task_struct *task); : amask (AMASK_CIX) ? "ev6" : "ev67"); \ })
-#define SET_PERSONALITY(EX) \ - set_personality(((EX).e_flags & EF_ALPHA_32BIT) \ - ? PER_LINUX_32BIT : PER_LINUX) - extern int alpha_l1i_cacheshape; extern int alpha_l1d_cacheshape; extern int alpha_l2_cacheshape; diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h index 635f0a5f5bbde..02e8817a89212 100644 --- a/arch/alpha/include/asm/pgtable.h +++ b/arch/alpha/include/asm/pgtable.h @@ -360,7 +360,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
extern void paging_init(void);
-/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT. */ +/* We have our own get_unmapped_area */ #define HAVE_ARCH_UNMAPPED_AREA
#endif /* _ALPHA_PGTABLE_H */ diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h index 55bb1c09fd39d..5dce5518a2111 100644 --- a/arch/alpha/include/asm/processor.h +++ b/arch/alpha/include/asm/processor.h @@ -8,23 +8,19 @@ #ifndef __ASM_ALPHA_PROCESSOR_H #define __ASM_ALPHA_PROCESSOR_H
-#include <linux/personality.h> /* for ADDR_LIMIT_32BIT */ - /* * We have a 42-bit user address space: 4TB user VM... */ #define TASK_SIZE (0x40000000000UL)
-#define STACK_TOP \ - (current->personality & ADDR_LIMIT_32BIT ? 0x80000000 : 0x00120000000UL) +#define STACK_TOP (0x00120000000UL)
#define STACK_TOP_MAX 0x00120000000UL
/* This decides where the kernel will search for a free chunk of vm * space during mmap's. */ -#define TASK_UNMAPPED_BASE \ - ((current->personality & ADDR_LIMIT_32BIT) ? 0x40000000 : TASK_SIZE / 2) +#define TASK_UNMAPPED_BASE (TASK_SIZE / 2)
/* This is dead. Everything has been moved to thread_info. */ struct thread_struct { }; diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c index c0424de9e7cda..077a1407be6d7 100644 --- a/arch/alpha/kernel/osf_sys.c +++ b/arch/alpha/kernel/osf_sys.c @@ -1211,8 +1211,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p) return ret; }
-/* Get an address range which is currently unmapped. Similar to the - generic version except that we know how to honor ADDR_LIMIT_32BIT. */ +/* Get an address range which is currently unmapped. */
static unsigned long arch_get_unmapped_area_1(unsigned long addr, unsigned long len, @@ -1231,13 +1230,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) { - unsigned long limit; - - /* "32 bit" actually means 31 bit, since pointers sign extend. */ - if (current->personality & ADDR_LIMIT_32BIT) - limit = 0x80000000; - else - limit = TASK_SIZE; + unsigned long limit = TASK_SIZE;
if (len > limit) return -ENOMEM;