diff options
Diffstat (limited to 'arch/mips/kernel/elf.c')
-rw-r--r-- | arch/mips/kernel/elf.c | 171 |
1 files changed, 155 insertions, 16 deletions
diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c index 3afffc30ee12..624e15dbd405 100644 --- a/arch/mips/kernel/elf.c +++ b/arch/mips/kernel/elf.c @@ -8,9 +8,18 @@ * option) any later version. */ +#include <linux/binfmts.h> #include <linux/elf.h> +#include <linux/export.h> #include <linux/sched.h> +#include <asm/cpu-features.h> +#include <asm/cpu-info.h> + +/* Whether to accept legacy-NaN and 2008-NaN user binaries. */ +bool mips_use_nan_legacy; +bool mips_use_nan_2008; + /* FPU modes */ enum { FP_FRE, @@ -68,15 +77,23 @@ static struct mode_req none_req = { true, true, false, true, true }; int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf, bool is_interp, struct arch_elf_state *state) { - struct elf32_hdr *ehdr32 = _ehdr; + union { + struct elf32_hdr e32; + struct elf64_hdr e64; + } *ehdr = _ehdr; struct elf32_phdr *phdr32 = _phdr; struct elf64_phdr *phdr64 = _phdr; struct mips_elf_abiflags_v0 abiflags; + bool elf32; + u32 flags; int ret; - /* Lets see if this is an O32 ELF */ - if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) { - if (ehdr32->e_flags & EF_MIPS_FP64) { + elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32; + flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags; + + /* Let's see if this is an O32 ELF */ + if (elf32) { + if (flags & EF_MIPS_FP64) { /* * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it * later if needed @@ -120,13 +137,50 @@ int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf, return 0; } -int arch_check_elf(void *_ehdr, bool has_interpreter, +int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr, struct arch_elf_state *state) { - struct elf32_hdr *ehdr = _ehdr; + union { + struct elf32_hdr e32; + struct elf64_hdr e64; + } *ehdr = _ehdr; + union { + struct elf32_hdr e32; + struct elf64_hdr e64; + } *iehdr = _interp_ehdr; struct mode_req prog_req, interp_req; int fp_abi, interp_fp_abi, abi0, abi1, max_abi; - bool is_mips64; + bool elf32; + u32 flags; + + elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32; + flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags; + + /* + * Determine the NaN personality, reject the binary if not allowed. + * Also ensure that any interpreter matches the executable. + */ + if (flags & EF_MIPS_NAN2008) { + if (mips_use_nan_2008) + state->nan_2008 = 1; + else + return -ENOEXEC; + } else { + if (mips_use_nan_legacy) + state->nan_2008 = 0; + else + return -ENOEXEC; + } + if (has_interpreter) { + bool ielf32; + u32 iflags; + + ielf32 = iehdr->e32.e_ident[EI_CLASS] == ELFCLASS32; + iflags = ielf32 ? iehdr->e32.e_flags : iehdr->e64.e_flags; + + if ((flags ^ iflags) & EF_MIPS_NAN2008) + return -ELIBBAD; + } if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) return 0; @@ -142,21 +196,18 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, abi0 = abi1 = fp_abi; } - is_mips64 = (ehdr->e_ident[EI_CLASS] == ELFCLASS64) || - (ehdr->e_flags & EF_MIPS_ABI2); + if (elf32 && !(flags & EF_MIPS_ABI2)) { + /* Default to a mode capable of running code expecting FR=0 */ + state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0; - if (is_mips64) { + /* Allow all ABIs we know about */ + max_abi = MIPS_ABI_FP_64A; + } else { /* MIPS64 code always uses FR=1, thus the default is easy */ state->overall_fp_mode = FP_FR1; /* Disallow access to the various FPXX & FP64 ABIs */ max_abi = MIPS_ABI_FP_SOFT; - } else { - /* Default to a mode capable of running code expecting FR=0 */ - state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0; - - /* Allow all ABIs we know about */ - max_abi = MIPS_ABI_FP_64A; } if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) || @@ -254,3 +305,91 @@ void mips_set_personality_fp(struct arch_elf_state *state) BUG(); } } + +/* + * Select the IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode + * in FCSR according to the ELF NaN personality. + */ +void mips_set_personality_nan(struct arch_elf_state *state) +{ + struct cpuinfo_mips *c = &boot_cpu_data; + struct task_struct *t = current; + + t->thread.fpu.fcr31 = c->fpu_csr31; + switch (state->nan_2008) { + case 0: + break; + case 1: + if (!(c->fpu_msk31 & FPU_CSR_NAN2008)) + t->thread.fpu.fcr31 |= FPU_CSR_NAN2008; + if (!(c->fpu_msk31 & FPU_CSR_ABS2008)) + t->thread.fpu.fcr31 |= FPU_CSR_ABS2008; + break; + default: + BUG(); + } +} + +static int noexec = EXSTACK_DEFAULT; + +/* + * kernel parameter: noexec=on|off + * + * Force indicating stack and heap as non-executable or + * executable regardless of PT_GNU_STACK entry or CPU XI + * (execute inhibit) support. Valid valuess are: on, off. + * + * noexec=on: force indicating non-executable + * stack and heap + * noexec=off: force indicating executable + * stack and heap + * + * If this parameter is omitted, stack and heap will be + * indicated non-executable or executable as they are + * actually set up, which depends on PT_GNU_STACK entry + * and possibly other factors (for instance, CPU XI + * support). + * + * NOTE: Using noexec=on on a system without CPU XI + * support is not recommended since there is no actual + * HW support that provide non-executable stack/heap. + * Use only for debugging purposes and not in a + * production environment. + */ +static int __init noexec_setup(char *str) +{ + if (!strcmp(str, "on")) + noexec = EXSTACK_DISABLE_X; + else if (!strcmp(str, "off")) + noexec = EXSTACK_ENABLE_X; + else + pr_err("Malformed noexec format! noexec=on|off\n"); + + return 1; +} +__setup("noexec=", noexec_setup); + +int mips_elf_read_implies_exec(void *elf_ex, int exstack) +{ + switch (noexec) { + case EXSTACK_DISABLE_X: + return 0; + case EXSTACK_ENABLE_X: + return 1; + default: + break; + } + + if (exstack != EXSTACK_DISABLE_X) { + /* The binary doesn't request a non-executable stack */ + return 1; + } + + if (!cpu_has_rixi) { + /* The CPU doesn't support non-executable memory */ + return 1; + } + + return 0; +} +EXPORT_SYMBOL(mips_elf_read_implies_exec); |