diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index 88a9f433f6fc3ca7affc6c9a011622d26e10ada9..3a2b775e845893513e2ab187ca95955e0be17848 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -122,17 +122,4 @@ config SPINLOCK_TEST
help
Add several files to the debugfs to test spinlock speed.
-config FP32XX_HYBRID_FPRS
- bool "Run FP32 & FPXX code with hybrid FPRs"
- depends on MIPS_O32_FP64_SUPPORT
- help
- The hybrid FPR scheme is normally used only when a program needs to
- execute a mix of FP32 & FP64A code, since the trapping & emulation
- that it entails is expensive. When enabled, this option will lead
- to the kernel running programs which use the FP32 & FPXX FP ABIs
- using the hybrid FPR scheme, which can be useful for debugging
- purposes.
-
- If unsure, say N.
-
endmenu
diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index eb4d95de619c5dca7543ed551267e43799f4ca11..535f196ffe02da7ad769ab0b7053b4dd5253dd82 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -417,13 +417,15 @@ extern unsigned long arch_randomize_brk(struct mm_struct *mm);
struct arch_elf_state {
int fp_abi;
int interp_fp_abi;
- int overall_abi;
+ int overall_fp_mode;
};
+#define MIPS_ABI_FP_UNKNOWN (-1) /* Unknown FP ABI (kernel internal) */
+
#define INIT_ARCH_ELF_STATE { \
- .fp_abi = -1, \
- .interp_fp_abi = -1, \
- .overall_abi = -1, \
+ .fp_abi = MIPS_ABI_FP_UNKNOWN, \
+ .interp_fp_abi = MIPS_ABI_FP_UNKNOWN, \
+ .overall_fp_mode = -1, \
}
extern int arch_elf_pt_proc(void *ehdr, void *phdr, struct file *elf,
diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
index c92b15df6893f555549bf3cc51bf6c39f78e1875..d2c09f6475c5cb5454b34ed1c498d43fdc31b29e 100644
--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -11,29 +11,112 @@
#include <linux/elf.h>
#include <linux/sched.h>
+/* FPU modes */
enum {
- FP_ERROR = -1,
- FP_DOUBLE_64A = -2,
+ 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)
{
- struct elfhdr *ehdr = _ehdr;
- struct elf_phdr *phdr = _phdr;
+ struct elf32_hdr *ehdr32 = _ehdr;
+ struct elf32_phdr *phdr32 = _phdr;
+ struct elf64_phdr *phdr64 = _phdr;
struct mips_elf_abiflags_v0 abiflags;
int ret;
- if (config_enabled(CONFIG_64BIT) &&
- (ehdr->e_ident[EI_CLASS] != ELFCLASS32))
- return 0;
- if (phdr->p_type != PT_MIPS_ABIFLAGS)
- return 0;
- if (phdr->p_filesz < sizeof(abiflags))
- return -EINVAL;
+ /* Lets see if this is an O32 ELF */
+ if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) {
+ /* FR = 1 for N32 */
+ if (ehdr32->e_flags & EF_MIPS_ABI2)
+ state->overall_fp_mode = FP_FR1;
+ else
+ /* Set a good default FPU mode for O32 */
+ state->overall_fp_mode = cpu_has_mips_r6 ?
+ FP_FRE : FP_FR0;
+
+ if (ehdr32->e_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;
+
+ ret = kernel_read(elf, phdr32->p_offset,
+ (char *)&abiflags,
+ sizeof(abiflags));
+ } else {
+ /* FR=1 is really the only option for 64-bit */
+ state->overall_fp_mode = FP_FR1;
+
+ if (phdr64->p_type != PT_MIPS_ABIFLAGS)
+ return 0;
+ if (phdr64->p_filesz < sizeof(abiflags))
+ return -EINVAL;
+
+ ret = kernel_read(elf, phdr64->p_offset,
+ (char *)&abiflags,
+ sizeof(abiflags));
+ }
- ret = kernel_read(elf, phdr->p_offset, (char *)&abiflags,
- sizeof(abiflags));
if (ret < 0)
return ret;
if (ret != sizeof(abiflags))
@@ -48,35 +131,30 @@ int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
return 0;
}
-static inline unsigned get_fp_abi(struct elfhdr *ehdr, int in_abi)
+static inline unsigned get_fp_abi(int in_abi)
{
/* If the ABI requirement is provided, simply return that */
- if (in_abi != -1)
+ if (in_abi != MIPS_ABI_FP_UNKNOWN)
return in_abi;
- /* If the EF_MIPS_FP64 flag was set, return MIPS_ABI_FP_64 */
- if (ehdr->e_flags & EF_MIPS_FP64)
- return MIPS_ABI_FP_64;
-
- /* Default to MIPS_ABI_FP_DOUBLE */
- return MIPS_ABI_FP_DOUBLE;
+ /* Unknown ABI */
+ return MIPS_ABI_FP_UNKNOWN;
}
int arch_check_elf(void *_ehdr, bool has_interpreter,
struct arch_elf_state *state)
{
- struct elfhdr *ehdr = _ehdr;
- unsigned fp_abi, interp_fp_abi, abi0, abi1;
+ struct elf32_hdr *ehdr = _ehdr;
+ struct mode_req prog_req, interp_req;
+ int fp_abi, interp_fp_abi, abi0, abi1, max_abi;
- /* Ignore non-O32 binaries */
- if (config_enabled(CONFIG_64BIT) &&
- (ehdr->e_ident[EI_CLASS] != ELFCLASS32))
+ if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
return 0;
- fp_abi = get_fp_abi(ehdr, state->fp_abi);
+ fp_abi = get_fp_abi(state->fp_abi);
if (has_interpreter) {
- interp_fp_abi = get_fp_abi(ehdr, state->interp_fp_abi);
+ interp_fp_abi = get_fp_abi(state->interp_fp_abi);
abi0 = min(fp_abi, interp_fp_abi);
abi1 = max(fp_abi, interp_fp_abi);
@@ -84,108 +162,103 @@ int arch_check_elf(void *_ehdr, bool has_interpreter,
abi0 = abi1 = fp_abi;
}
- state->overall_abi = FP_ERROR;
-
- if (abi0 == abi1) {
- state->overall_abi = abi0;
- } else if (abi0 == MIPS_ABI_FP_ANY) {
- state->overall_abi = abi1;
- } else if (abi0 == MIPS_ABI_FP_DOUBLE) {
- switch (abi1) {
- case MIPS_ABI_FP_XX:
- state->overall_abi = MIPS_ABI_FP_DOUBLE;
- break;
-
- case MIPS_ABI_FP_64A:
- state->overall_abi = FP_DOUBLE_64A;
- break;
- }
- } else if (abi0 == MIPS_ABI_FP_SINGLE ||
- abi0 == MIPS_ABI_FP_SOFT) {
- /* Cannot link with other ABIs */
- } else if (abi0 == MIPS_ABI_FP_OLD_64) {
- switch (abi1) {
- case MIPS_ABI_FP_XX:
- case MIPS_ABI_FP_64:
- case MIPS_ABI_FP_64A:
- state->overall_abi = MIPS_ABI_FP_64;
- break;
- }
- } else if (abi0 == MIPS_ABI_FP_XX ||
- abi0 == MIPS_ABI_FP_64 ||
- abi0 == MIPS_ABI_FP_64A) {
- state->overall_abi = MIPS_ABI_FP_64;
- }
+ /* ABI limits. O32 = FP_64A, N32/N64 = FP_SOFT */
+ max_abi = ((ehdr->e_ident[EI_CLASS] == ELFCLASS32) &&
+ (!(ehdr->e_flags & EF_MIPS_ABI2))) ?
+ MIPS_ABI_FP_64A : MIPS_ABI_FP_SOFT;
- switch (state->overall_abi) {
- case MIPS_ABI_FP_64:
- case MIPS_ABI_FP_64A:
- case FP_DOUBLE_64A:
- if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
- return -ELIBBAD;
- break;
+ 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];
- case FP_ERROR:
+ /*
+ * 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 = ((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;
}
-void mips_set_personality_fp(struct arch_elf_state *state)
+static inline void set_thread_fp_mode(int hybrid, int regs32)
{
- if (config_enabled(CONFIG_FP32XX_HYBRID_FPRS)) {
- /*
- * Use hybrid FPRs for all code which can correctly execute
- * with that mode.
- */
- switch (state->overall_abi) {
- case MIPS_ABI_FP_DOUBLE:
- case MIPS_ABI_FP_SINGLE:
- case MIPS_ABI_FP_SOFT:
- case MIPS_ABI_FP_XX:
- case MIPS_ABI_FP_ANY:
- /* FR=1, FRE=1 */
- clear_thread_flag(TIF_32BIT_FPREGS);
- set_thread_flag(TIF_HYBRID_FPREGS);
- return;
- }
- }
-
- switch (state->overall_abi) {
- case MIPS_ABI_FP_DOUBLE:
- case MIPS_ABI_FP_SINGLE:
- case MIPS_ABI_FP_SOFT:
- /* FR=0 */
- set_thread_flag(TIF_32BIT_FPREGS);
+ if (hybrid)
+ set_thread_flag(TIF_HYBRID_FPREGS);
+ else
clear_thread_flag(TIF_HYBRID_FPREGS);
- break;
-
- case FP_DOUBLE_64A:
- /* FR=1, FRE=1 */
+ if (regs32)
+ set_thread_flag(TIF_32BIT_FPREGS);
+ else
clear_thread_flag(TIF_32BIT_FPREGS);
- set_thread_flag(TIF_HYBRID_FPREGS);
- break;
+}
- case MIPS_ABI_FP_64:
- case MIPS_ABI_FP_64A:
- /* FR=1, FRE=0 */
- clear_thread_flag(TIF_32BIT_FPREGS);
- clear_thread_flag(TIF_HYBRID_FPREGS);
- break;
+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.
+ */
- case MIPS_ABI_FP_XX:
- case MIPS_ABI_FP_ANY:
- if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
- set_thread_flag(TIF_32BIT_FPREGS);
- else
- clear_thread_flag(TIF_32BIT_FPREGS);
+ if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
+ return;
- clear_thread_flag(TIF_HYBRID_FPREGS);
+ 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:
- case FP_ERROR:
BUG();
}
}