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authorPaul Burton <paul.burton@imgtec.com>2014-09-11 03:30:22 -0400
committerRalf Baechle <ralf@linux-mips.org>2014-11-24 01:45:07 -0500
commit90cee759f08a6b7a8daab9977d3e163ebbcac220 (patch)
tree8aba4b7cdc422b89f378bd38cf85aa266a322f64 /arch/mips/kernel/elf.c
parent6cd962292d9eb3b3e7189fde532f7e49f395cccb (diff)
MIPS: ELF: Set FP mode according to .MIPS.abiflags
This patch reads the .MIPS.abiflags section when it is present, and sets the FP mode of the task accordingly. Any loaded ELF files which do not contain a .MIPS.abiflags section will continue to observe the previous behaviour, that is FR=1 if EF_MIPS_FP64 is set else FR=0. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/7681/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/elf.c')
-rw-r--r--arch/mips/kernel/elf.c173
1 files changed, 173 insertions, 0 deletions
diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
new file mode 100644
index 000000000000..0933e0726f64
--- /dev/null
+++ b/arch/mips/kernel/elf.c
@@ -0,0 +1,173 @@
1/*
2 * Copyright (C) 2014 Imagination Technologies
3 * Author: Paul Burton <paul.burton@imgtec.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; either version 2 of the License, or (at your
8 * option) any later version.
9 */
10
11#include <linux/elf.h>
12#include <linux/sched.h>
13
14enum {
15 FP_ERROR = -1,
16 FP_DOUBLE_64A = -2,
17};
18
19int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
20 bool is_interp, struct arch_elf_state *state)
21{
22 struct elfhdr *ehdr = _ehdr;
23 struct elf_phdr *phdr = _phdr;
24 struct mips_elf_abiflags_v0 abiflags;
25 int ret;
26
27 if (config_enabled(CONFIG_64BIT) &&
28 (ehdr->e_ident[EI_CLASS] != ELFCLASS32))
29 return 0;
30 if (phdr->p_type != PT_MIPS_ABIFLAGS)
31 return 0;
32 if (phdr->p_filesz < sizeof(abiflags))
33 return -EINVAL;
34
35 ret = kernel_read(elf, phdr->p_offset, (char *)&abiflags,
36 sizeof(abiflags));
37 if (ret < 0)
38 return ret;
39 if (ret != sizeof(abiflags))
40 return -EIO;
41
42 /* Record the required FP ABIs for use by mips_check_elf */
43 if (is_interp)
44 state->interp_fp_abi = abiflags.fp_abi;
45 else
46 state->fp_abi = abiflags.fp_abi;
47
48 return 0;
49}
50
51static inline unsigned get_fp_abi(struct elfhdr *ehdr, int in_abi)
52{
53 /* If the ABI requirement is provided, simply return that */
54 if (in_abi != -1)
55 return in_abi;
56
57 /* If the EF_MIPS_FP64 flag was set, return MIPS_ABI_FP_64 */
58 if (ehdr->e_flags & EF_MIPS_FP64)
59 return MIPS_ABI_FP_64;
60
61 /* Default to MIPS_ABI_FP_DOUBLE */
62 return MIPS_ABI_FP_DOUBLE;
63}
64
65int arch_check_elf(void *_ehdr, bool has_interpreter,
66 struct arch_elf_state *state)
67{
68 struct elfhdr *ehdr = _ehdr;
69 unsigned fp_abi, interp_fp_abi, abi0, abi1;
70
71 /* Ignore non-O32 binaries */
72 if (config_enabled(CONFIG_64BIT) &&
73 (ehdr->e_ident[EI_CLASS] != ELFCLASS32))
74 return 0;
75
76 fp_abi = get_fp_abi(ehdr, state->fp_abi);
77
78 if (has_interpreter) {
79 interp_fp_abi = get_fp_abi(ehdr, state->interp_fp_abi);
80
81 abi0 = min(fp_abi, interp_fp_abi);
82 abi1 = max(fp_abi, interp_fp_abi);
83 } else {
84 abi0 = abi1 = fp_abi;
85 }
86
87 state->overall_abi = FP_ERROR;
88
89 if (abi0 == abi1) {
90 state->overall_abi = abi0;
91 } else if (abi0 == MIPS_ABI_FP_ANY) {
92 state->overall_abi = abi1;
93 } else if (abi0 == MIPS_ABI_FP_DOUBLE) {
94 switch (abi1) {
95 case MIPS_ABI_FP_XX:
96 state->overall_abi = MIPS_ABI_FP_DOUBLE;
97 break;
98
99 case MIPS_ABI_FP_64A:
100 state->overall_abi = FP_DOUBLE_64A;
101 break;
102 }
103 } else if (abi0 == MIPS_ABI_FP_SINGLE ||
104 abi0 == MIPS_ABI_FP_SOFT) {
105 /* Cannot link with other ABIs */
106 } else if (abi0 == MIPS_ABI_FP_OLD_64) {
107 switch (abi1) {
108 case MIPS_ABI_FP_XX:
109 case MIPS_ABI_FP_64:
110 case MIPS_ABI_FP_64A:
111 state->overall_abi = MIPS_ABI_FP_64;
112 break;
113 }
114 } else if (abi0 == MIPS_ABI_FP_XX ||
115 abi0 == MIPS_ABI_FP_64 ||
116 abi0 == MIPS_ABI_FP_64A) {
117 state->overall_abi = MIPS_ABI_FP_64;
118 }
119
120 switch (state->overall_abi) {
121 case MIPS_ABI_FP_64:
122 case MIPS_ABI_FP_64A:
123 case FP_DOUBLE_64A:
124 if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
125 return -ELIBBAD;
126 break;
127
128 case FP_ERROR:
129 return -ELIBBAD;
130 }
131
132 return 0;
133}
134
135void mips_set_personality_fp(struct arch_elf_state *state)
136{
137 switch (state->overall_abi) {
138 case MIPS_ABI_FP_DOUBLE:
139 case MIPS_ABI_FP_SINGLE:
140 case MIPS_ABI_FP_SOFT:
141 /* FR=0 */
142 set_thread_flag(TIF_32BIT_FPREGS);
143 clear_thread_flag(TIF_HYBRID_FPREGS);
144 break;
145
146 case FP_DOUBLE_64A:
147 /* FR=1, FRE=1 */
148 clear_thread_flag(TIF_32BIT_FPREGS);
149 set_thread_flag(TIF_HYBRID_FPREGS);
150 break;
151
152 case MIPS_ABI_FP_64:
153 case MIPS_ABI_FP_64A:
154 /* FR=1, FRE=0 */
155 clear_thread_flag(TIF_32BIT_FPREGS);
156 clear_thread_flag(TIF_HYBRID_FPREGS);
157 break;
158
159 case MIPS_ABI_FP_XX:
160 case MIPS_ABI_FP_ANY:
161 if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
162 set_thread_flag(TIF_32BIT_FPREGS);
163 else
164 clear_thread_flag(TIF_32BIT_FPREGS);
165
166 clear_thread_flag(TIF_HYBRID_FPREGS);
167 break;
168
169 default:
170 case FP_ERROR:
171 BUG();
172 }
173}
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