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-rw-r--r--arch/mips/kernel/elf.c343
1 files changed, 343 insertions, 0 deletions
diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
new file mode 100644
index 000000000..7b045d2a0
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+++ b/arch/mips/kernel/elf.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2014 Imagination Technologies
+ * Author: Paul Burton <paul.burton@mips.com>
+ */
+
+#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>
+
+#ifdef CONFIG_MIPS_FP_SUPPORT
+
+/* 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,
+ FP_FR0,
+ FP_FR1,
+};
+
+/**
+ * struct mode_req - ABI FPU mode requirements
+ * @single: The program being loaded needs an FPU but it will only issue
+ * single precision instructions meaning that it can execute in
+ * either FR0 or FR1.
+ * @soft: The soft(-float) requirement means that the program being
+ * loaded needs has no FPU dependency at all (i.e. it has no
+ * FPU instructions).
+ * @fr1: The program being loaded depends on FPU being in FR=1 mode.
+ * @frdefault: The program being loaded depends on the default FPU mode.
+ * That is FR0 for O32 and FR1 for N32/N64.
+ * @fre: The program being loaded depends on FPU with FRE=1. This mode is
+ * a bridge which uses FR=1 whilst still being able to maintain
+ * full compatibility with pre-existing code using the O32 FP32
+ * ABI.
+ *
+ * More information about the FP ABIs can be found here:
+ *
+ * https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking#10.4.1._Basic_mode_set-up
+ *
+ */
+
+struct mode_req {
+ bool single;
+ bool soft;
+ bool fr1;
+ bool frdefault;
+ bool fre;
+};
+
+static const struct mode_req fpu_reqs[] = {
+ [MIPS_ABI_FP_ANY] = { true, true, true, true, true },
+ [MIPS_ABI_FP_DOUBLE] = { false, false, false, true, true },
+ [MIPS_ABI_FP_SINGLE] = { true, false, false, false, false },
+ [MIPS_ABI_FP_SOFT] = { false, true, false, false, false },
+ [MIPS_ABI_FP_OLD_64] = { false, false, false, false, false },
+ [MIPS_ABI_FP_XX] = { false, false, true, true, true },
+ [MIPS_ABI_FP_64] = { false, false, true, false, false },
+ [MIPS_ABI_FP_64A] = { false, false, true, false, true }
+};
+
+/*
+ * Mode requirements when .MIPS.abiflags is not present in the ELF.
+ * Not present means that everything is acceptable except FR1.
+ */
+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)
+{
+ 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;
+ loff_t pos;
+
+ 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
+ */
+ if (is_interp)
+ state->interp_fp_abi = MIPS_ABI_FP_OLD_64;
+ else
+ state->fp_abi = MIPS_ABI_FP_OLD_64;
+ }
+ if (phdr32->p_type != PT_MIPS_ABIFLAGS)
+ return 0;
+
+ if (phdr32->p_filesz < sizeof(abiflags))
+ return -EINVAL;
+ pos = phdr32->p_offset;
+ } else {
+ if (phdr64->p_type != PT_MIPS_ABIFLAGS)
+ return 0;
+ if (phdr64->p_filesz < sizeof(abiflags))
+ return -EINVAL;
+ pos = phdr64->p_offset;
+ }
+
+ ret = kernel_read(elf, &abiflags, sizeof(abiflags), &pos);
+ if (ret < 0)
+ return ret;
+ if (ret != sizeof(abiflags))
+ return -EIO;
+
+ /* Record the required FP ABIs for use by mips_check_elf */
+ if (is_interp)
+ state->interp_fp_abi = abiflags.fp_abi;
+ else
+ state->fp_abi = abiflags.fp_abi;
+
+ return 0;
+}
+
+int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr,
+ struct arch_elf_state *state)
+{
+ 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 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 (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
+ return 0;
+
+ fp_abi = state->fp_abi;
+
+ if (has_interpreter) {
+ interp_fp_abi = state->interp_fp_abi;
+
+ abi0 = min(fp_abi, interp_fp_abi);
+ abi1 = max(fp_abi, interp_fp_abi);
+ } else {
+ abi0 = abi1 = fp_abi;
+ }
+
+ 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;
+
+ /* 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;
+ }
+
+ if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) ||
+ (abi1 > max_abi && abi1 != MIPS_ABI_FP_UNKNOWN))
+ return -ELIBBAD;
+
+ /* It's time to determine the FPU mode requirements */
+ prog_req = (abi0 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi0];
+ interp_req = (abi1 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi1];
+
+ /*
+ * Check whether the program's and interp's ABIs have a matching FPU
+ * mode requirement.
+ */
+ prog_req.single = interp_req.single && prog_req.single;
+ prog_req.soft = interp_req.soft && prog_req.soft;
+ prog_req.fr1 = interp_req.fr1 && prog_req.fr1;
+ prog_req.frdefault = interp_req.frdefault && prog_req.frdefault;
+ prog_req.fre = interp_req.fre && prog_req.fre;
+
+ /*
+ * Determine the desired FPU mode
+ *
+ * Decision making:
+ *
+ * - We want FR_FRE if FRE=1 and both FR=1 and FR=0 are false. This
+ * means that we have a combination of program and interpreter
+ * that inherently require the hybrid FP mode.
+ * - If FR1 and FRDEFAULT is true, that means we hit the any-abi or
+ * fpxx case. This is because, in any-ABI (or no-ABI) we have no FPU
+ * instructions so we don't care about the mode. We will simply use
+ * the one preferred by the hardware. In fpxx case, that ABI can
+ * handle both FR=1 and FR=0, so, again, we simply choose the one
+ * preferred by the hardware. Next, if we only use single-precision
+ * FPU instructions, and the default ABI FPU mode is not good
+ * (ie single + any ABI combination), we set again the FPU mode to the
+ * one is preferred by the hardware. Next, if we know that the code
+ * will only use single-precision instructions, shown by single being
+ * true but frdefault being false, then we again set the FPU mode to
+ * the one that is preferred by the hardware.
+ * - We want FP_FR1 if that's the only matching mode and the default one
+ * is not good.
+ * - Return with -ELIBADD if we can't find a matching FPU mode.
+ */
+ if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1)
+ state->overall_fp_mode = FP_FRE;
+ else if ((prog_req.fr1 && prog_req.frdefault) ||
+ (prog_req.single && !prog_req.frdefault))
+ /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
+ state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
+ cpu_has_mips_r2_r6) ?
+ FP_FR1 : FP_FR0;
+ else if (prog_req.fr1)
+ state->overall_fp_mode = FP_FR1;
+ else if (!prog_req.fre && !prog_req.frdefault &&
+ !prog_req.fr1 && !prog_req.single && !prog_req.soft)
+ return -ELIBBAD;
+
+ return 0;
+}
+
+static inline void set_thread_fp_mode(int hybrid, int regs32)
+{
+ if (hybrid)
+ set_thread_flag(TIF_HYBRID_FPREGS);
+ else
+ clear_thread_flag(TIF_HYBRID_FPREGS);
+ if (regs32)
+ set_thread_flag(TIF_32BIT_FPREGS);
+ else
+ clear_thread_flag(TIF_32BIT_FPREGS);
+}
+
+void mips_set_personality_fp(struct arch_elf_state *state)
+{
+ /*
+ * This function is only ever called for O32 ELFs so we should
+ * not be worried about N32/N64 binaries.
+ */
+
+ if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
+ return;
+
+ switch (state->overall_fp_mode) {
+ case FP_FRE:
+ set_thread_fp_mode(1, 0);
+ break;
+ case FP_FR0:
+ set_thread_fp_mode(0, 1);
+ break;
+ case FP_FR1:
+ set_thread_fp_mode(0, 0);
+ break;
+ default:
+ 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();
+ }
+}
+
+#endif /* CONFIG_MIPS_FP_SUPPORT */
+
+int mips_elf_read_implies_exec(void *elf_ex, int exstack)
+{
+ 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);
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