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changeset 1780:af5da3b293cb draft

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Revert a broken commit that breaks mips on 4.0.
author Rob Landley <rob@landley.net>
date Thu, 23 Jul 2015 09:06:13 -0500
parents 444516902275
children b27851ab2795
files sources/patches/linux-fixmips.patch
diffstat 1 files changed, 441 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sources/patches/linux-fixmips.patch	Thu Jul 23 09:06:13 2015 -0500
@@ -0,0 +1,441 @@
+The below commit broke mips floating point. Symptom: busybox
+"awk '{print $2}' /proc/mounts" hangs because the $2 is NAN and
+it loops endlessly trying to parse it.
+
+The later fixup patch (620b15503457) doesn't fix the problem.
+
+commit 46490b572544fa908be051f7872beb2941e55ede
+Author: Markos Chandras <markos.chandras@imgtec.com>
+Date:   Thu Jan 8 09:32:25 2015 +0000
+
+    MIPS: kernel: elf: Improve the overall ABI and FPU mode checks
+    
+    The previous implementation did not cover all possible FPU combinations
+    and it silently allowed ABI incompatible objects to be loaded with the
+    wrong ABI. For example, the previous logic would set the FP_64 ABI as
+    the matching ABI for an FP_XX object combined with an FP_64A object.
+    This was wrong, and the matching ABI should have been FP_64A.
+    The previous logic is now replaced with a new one which determines
+    the appropriate FPU mode to be used rather than the FP ABI. This has
+    the advantage that the entire logic is much simpler since it is the FPU
+    mode we are interested in rather than the FP ABI resulting to code
+    simplifications. This also removes the now obsolete FP32XX_HYBRID_FPRS
+    option.
+    
+    Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
+    Cc: Paul Burton <paul.burton@imgtec.com>
+    Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
+
+diff --git b/arch/mips/Kconfig.debug a/arch/mips/Kconfig.debug
+index 3a2b775..88a9f43 100644
+--- b/arch/mips/Kconfig.debug
++++ a/arch/mips/Kconfig.debug
+@@ -122,4 +122,17 @@ 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 b/arch/mips/include/asm/elf.h a/arch/mips/include/asm/elf.h
+index 535f196..eb4d95d 100644
+--- b/arch/mips/include/asm/elf.h
++++ a/arch/mips/include/asm/elf.h
+@@ -417,15 +417,13 @@ extern unsigned long arch_randomize_brk(struct mm_struct *mm);
+ struct arch_elf_state {
+ 	int fp_abi;
+ 	int interp_fp_abi;
+-	int overall_fp_mode;
++	int overall_abi;
+ };
+ 
+-#define MIPS_ABI_FP_UNKNOWN	(-1)	/* Unknown FP ABI (kernel internal) */
+-
+ #define INIT_ARCH_ELF_STATE {			\
+-	.fp_abi = MIPS_ABI_FP_UNKNOWN,		\
+-	.interp_fp_abi = MIPS_ABI_FP_UNKNOWN,	\
+-	.overall_fp_mode = -1,			\
++	.fp_abi = -1,				\
++	.interp_fp_abi = -1,			\
++	.overall_abi = -1,			\
+ }
+ 
+ extern int arch_elf_pt_proc(void *ehdr, void *phdr, struct file *elf,
+diff --git b/arch/mips/kernel/elf.c a/arch/mips/kernel/elf.c
+index d2c09f6..c92b15d 100644
+--- b/arch/mips/kernel/elf.c
++++ a/arch/mips/kernel/elf.c
+@@ -11,112 +11,29 @@
+ #include <linux/elf.h>
+ #include <linux/sched.h>
+ 
+-/* FPU modes */
+ enum {
+-	FP_FRE,
+-	FP_FR0,
+-	FP_FR1,
++	FP_ERROR = -1,
++	FP_DOUBLE_64A = -2,
+ };
+ 
+-/**
+- * 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 elf32_hdr *ehdr32 = _ehdr;
+-	struct elf32_phdr *phdr32 = _phdr;
+-	struct elf64_phdr *phdr64 = _phdr;
++	struct elfhdr *ehdr = _ehdr;
++	struct elf_phdr *phdr = _phdr;
+ 	struct mips_elf_abiflags_v0 abiflags;
+ 	int ret;
+ 
+-	/* 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));
+-	}
++	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;
+ 
++	ret = kernel_read(elf, phdr->p_offset, (char *)&abiflags,
++			  sizeof(abiflags));
+ 	if (ret < 0)
+ 		return ret;
+ 	if (ret != sizeof(abiflags))
+@@ -131,30 +48,35 @@ int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
+ 	return 0;
+ }
+ 
+-static inline unsigned get_fp_abi(int in_abi)
++static inline unsigned get_fp_abi(struct elfhdr *ehdr, int in_abi)
+ {
+ 	/* If the ABI requirement is provided, simply return that */
+-	if (in_abi != MIPS_ABI_FP_UNKNOWN)
++	if (in_abi != -1)
+ 		return in_abi;
+ 
+-	/* Unknown ABI */
+-	return MIPS_ABI_FP_UNKNOWN;
++	/* 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;
+ }
+ 
+ int arch_check_elf(void *_ehdr, bool has_interpreter,
+ 		   struct arch_elf_state *state)
+ {
+-	struct elf32_hdr *ehdr = _ehdr;
+-	struct mode_req prog_req, interp_req;
+-	int fp_abi, interp_fp_abi, abi0, abi1, max_abi;
++	struct elfhdr *ehdr = _ehdr;
++	unsigned fp_abi, interp_fp_abi, abi0, abi1;
+ 
+-	if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
++	/* Ignore non-O32 binaries */
++	if (config_enabled(CONFIG_64BIT) &&
++	    (ehdr->e_ident[EI_CLASS] != ELFCLASS32))
+ 		return 0;
+ 
+-	fp_abi = get_fp_abi(state->fp_abi);
++	fp_abi = get_fp_abi(ehdr, state->fp_abi);
+ 
+ 	if (has_interpreter) {
+-		interp_fp_abi = get_fp_abi(state->interp_fp_abi);
++		interp_fp_abi = get_fp_abi(ehdr, state->interp_fp_abi);
+ 
+ 		abi0 = min(fp_abi, interp_fp_abi);
+ 		abi1 = max(fp_abi, interp_fp_abi);
+@@ -162,103 +84,108 @@ int arch_check_elf(void *_ehdr, bool has_interpreter,
+ 		abi0 = abi1 = fp_abi;
+ 	}
+ 
+-	/* 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;
+-
+-	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];
++	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;
++	}
+ 
+-	/*
+-	 * 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;
++	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;
+ 
+-	/*
+-	 * 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)
++	case FP_ERROR:
+ 		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 (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;
++		}
++	}
+ 
+-	if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
+-		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);
++		clear_thread_flag(TIF_HYBRID_FPREGS);
++		break;
+ 
+-	switch (state->overall_fp_mode) {
+-	case FP_FRE:
+-		set_thread_fp_mode(1, 0);
++	case FP_DOUBLE_64A:
++		/* FR=1, FRE=1 */
++		clear_thread_flag(TIF_32BIT_FPREGS);
++		set_thread_flag(TIF_HYBRID_FPREGS);
+ 		break;
+-	case FP_FR0:
+-		set_thread_fp_mode(0, 1);
++
++	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;
+-	case FP_FR1:
+-		set_thread_fp_mode(0, 0);
++
++	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);
++
++		clear_thread_flag(TIF_HYBRID_FPREGS);
+ 		break;
++
+ 	default:
++	case FP_ERROR:
+ 		BUG();
+ 	}
+ }