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-rw-r--r--Documentation/kernel-parameters.txt35
-rw-r--r--arch/mips/include/asm/elf.h4
-rw-r--r--arch/mips/kernel/cpu-probe.c105
-rw-r--r--arch/mips/kernel/elf.c12
4 files changed, 142 insertions, 14 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 742f69d18fc8..4bcd23355e86 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1436,6 +1436,41 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
In such case C2/C3 won't be used again.
idle=nomwait: Disable mwait for CPU C-states
+ ieee754= [MIPS] Select IEEE Std 754 conformance mode
+ Format: { strict | legacy | 2008 | relaxed }
+ Default: strict
+
+ Choose which programs will be accepted for execution
+ based on the IEEE 754 NaN encoding(s) supported by
+ the FPU and the NaN encoding requested with the value
+ of an ELF file header flag individually set by each
+ binary. Hardware implementations are permitted to
+ support either or both of the legacy and the 2008 NaN
+ encoding mode.
+
+ Available settings are as follows:
+ strict accept binaries that request a NaN encoding
+ supported by the FPU
+ legacy only accept legacy-NaN binaries, if supported
+ by the FPU
+ 2008 only accept 2008-NaN binaries, if supported
+ by the FPU
+ relaxed accept any binaries regardless of whether
+ supported by the FPU
+
+ The FPU emulator is always able to support both NaN
+ encodings, so if no FPU hardware is present or it has
+ been disabled with 'nofpu', then the settings of
+ 'legacy' and '2008' strap the emulator accordingly,
+ 'relaxed' straps the emulator for both legacy-NaN and
+ 2008-NaN, whereas 'strict' enables legacy-NaN only on
+ legacy processors and both NaN encodings on MIPS32 or
+ MIPS64 CPUs.
+
+ The setting for ABS.fmt/NEG.fmt instruction execution
+ mode generally follows that for the NaN encoding,
+ except where unsupported by hardware.
+
ignore_loglevel [KNL]
Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging.
diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index 3dba5d05830c..cefb7a596878 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -447,6 +447,10 @@ struct arch_elf_state {
.overall_fp_mode = -1, \
}
+/* Whether to accept legacy-NaN and 2008-NaN user binaries. */
+extern bool mips_use_nan_legacy;
+extern bool mips_use_nan_2008;
+
extern int arch_elf_pt_proc(void *ehdr, void *phdr, struct file *elf,
bool is_interp, struct arch_elf_state *state);
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 0aa61a95eb4b..b725b713b9f8 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -151,26 +151,109 @@ static void cpu_set_fpu_2008(struct cpuinfo_mips *c)
}
/*
- * Set the IEEE 754 NaN encodings and ABS.fmt/NEG.fmt execution modes
- * for the FPU emulator. Clear the flags where required in case called
- * from `fpu_disable', to override details obtained from FPU hardware.
+ * IEEE 754 conformance mode to use. Affects the NaN encoding and the
+ * ABS.fmt/NEG.fmt execution mode.
+ */
+static enum { STRICT, LEGACY, STD2008, RELAXED } ieee754 = STRICT;
+
+/*
+ * Set the IEEE 754 NaN encodings and the ABS.fmt/NEG.fmt execution modes
+ * to support by the FPU emulator according to the IEEE 754 conformance
+ * mode selected. Note that "relaxed" straps the emulator so that it
+ * allows 2008-NaN binaries even for legacy processors.
*/
static void cpu_set_nofpu_2008(struct cpuinfo_mips *c)
{
+ c->options &= ~(MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY);
c->fpu_csr31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
- if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
- MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
- MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
- c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
- c->fpu_msk31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
- } else {
- c->options &= ~MIPS_CPU_NAN_2008;
+ c->fpu_msk31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
+
+ switch (ieee754) {
+ case STRICT:
+ if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
+ MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+ MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
+ c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
+ } else {
+ c->options |= MIPS_CPU_NAN_LEGACY;
+ c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+ }
+ break;
+ case LEGACY:
c->options |= MIPS_CPU_NAN_LEGACY;
c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+ break;
+ case STD2008:
+ c->options |= MIPS_CPU_NAN_2008;
+ c->fpu_csr31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+ c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+ break;
+ case RELAXED:
+ c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
+ break;
+ }
+}
+
+/*
+ * Override the IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode
+ * according to the "ieee754=" parameter.
+ */
+static void cpu_set_nan_2008(struct cpuinfo_mips *c)
+{
+ switch (ieee754) {
+ case STRICT:
+ mips_use_nan_legacy = !!cpu_has_nan_legacy;
+ mips_use_nan_2008 = !!cpu_has_nan_2008;
+ break;
+ case LEGACY:
+ mips_use_nan_legacy = !!cpu_has_nan_legacy;
+ mips_use_nan_2008 = !cpu_has_nan_legacy;
+ break;
+ case STD2008:
+ mips_use_nan_legacy = !cpu_has_nan_2008;
+ mips_use_nan_2008 = !!cpu_has_nan_2008;
+ break;
+ case RELAXED:
+ mips_use_nan_legacy = true;
+ mips_use_nan_2008 = true;
+ break;
}
}
/*
+ * IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode override
+ * settings:
+ *
+ * strict: accept binaries that request a NaN encoding supported by the FPU
+ * legacy: only accept legacy-NaN binaries
+ * 2008: only accept 2008-NaN binaries
+ * relaxed: accept any binaries regardless of whether supported by the FPU
+ */
+static int __init ieee754_setup(char *s)
+{
+ if (!s)
+ return -1;
+ else if (!strcmp(s, "strict"))
+ ieee754 = STRICT;
+ else if (!strcmp(s, "legacy"))
+ ieee754 = LEGACY;
+ else if (!strcmp(s, "2008"))
+ ieee754 = STD2008;
+ else if (!strcmp(s, "relaxed"))
+ ieee754 = RELAXED;
+ else
+ return -1;
+
+ if (!(boot_cpu_data.options & MIPS_CPU_FPU))
+ cpu_set_nofpu_2008(&boot_cpu_data);
+ cpu_set_nan_2008(&boot_cpu_data);
+
+ return 0;
+}
+
+early_param("ieee754", ieee754_setup);
+
+/*
* Set the FIR feature flags for the FPU emulator.
*/
static void cpu_set_nofpu_id(struct cpuinfo_mips *c)
@@ -212,6 +295,7 @@ static void cpu_set_fpu_opts(struct cpuinfo_mips *c)
cpu_set_fpu_fcsr_mask(c);
cpu_set_fpu_2008(c);
+ cpu_set_nan_2008(c);
}
/*
@@ -223,6 +307,7 @@ static void cpu_set_nofpu_opts(struct cpuinfo_mips *c)
c->fpu_msk31 = mips_nofpu_msk31;
cpu_set_nofpu_2008(c);
+ cpu_set_nan_2008(c);
cpu_set_nofpu_id(c);
}
diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
index f36a261b275c..c3c234dc0c07 100644
--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -13,6 +13,10 @@
#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,
@@ -150,16 +154,16 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr,
flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
/*
- * Determine the NaN personality, reject the binary if no hardware
- * support. Also ensure that any interpreter matches the executable.
+ * Determine the NaN personality, reject the binary if not allowed.
+ * Also ensure that any interpreter matches the executable.
*/
if (flags & EF_MIPS_NAN2008) {
- if (cpu_has_nan_2008)
+ if (mips_use_nan_2008)
state->nan_2008 = 1;
else
return -ENOEXEC;
} else {
- if (cpu_has_nan_legacy)
+ if (mips_use_nan_legacy)
state->nan_2008 = 0;
else
return -ENOEXEC;
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-03 21:22:34 +0000