mirror of
https://github.com/qemu/qemu.git
synced 2026-07-08 17:46:10 +00:00
84b920ccb5
QEMU keeps the MIPS FPU control/status register (FCSR, fcr31) in
env->active_fpu.fcr31. The rounding mode, flush-to-zero (FS), and
NaN-2008 mode bits in fcr31 are reflected into the derived
env->active_fpu.fp_status via set_float_rounding_mode() and friends;
every architectural write to FCSR goes through helper_ctc1() which
calls restore_fp_status() to keep the two in sync.
Both target_sigcontext variants (O32 and N32/N64) have an sc_fpc_csr
field that holds FCSR, but setup_sigcontext() never wrote it and
restore_sigcontext() never read it. As a result:
- The signal frame always delivered sc_fpc_csr == 0 to the handler,
so sigaction(SA_SIGINFO) handlers that inspect the interrupted
context see the wrong FCSR.
- On sigreturn, active_fpu.fcr31 retained whatever value the signal
handler last installed (if any), and active_fpu.fp_status was
never resynced. Interrupted code resumed with the wrong rounding
mode, FS flag, and NaN-2008 semantics.
Fix setup_sigcontext() to save fcr31 into sc_fpc_csr. Fix
restore_sigcontext() to read it back (masked to fcr31_rw_bitmask as
the kernel does) and call cpu_mips_restore_fp_status() to resync
fp_status from the restored fcr31.
Add cpu_mips_restore_fp_status() in target/mips/fpu.c (which already
defines ieee_rm and includes fpu_helper.h), and declare it in cpu.h.
Fixes: 084d0497a0 ("mips-linux-user: Save and restore fpu and dsp from sigcontext")
Cc: qemu-stable@nongnu.org
Signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
31 lines
797 B
C
31 lines
797 B
C
/*
|
|
* Helpers for emulation of FPU-related MIPS instructions.
|
|
*
|
|
* Copyright (C) 2004-2005 Jocelyn Mayer
|
|
*
|
|
* SPDX-License-Identifier: LGPL-2.1-or-later
|
|
*/
|
|
#include "qemu/osdep.h"
|
|
#include "fpu/softfloat-helpers.h"
|
|
#include "fpu_helper.h"
|
|
|
|
/* convert MIPS rounding mode in FCR31 to IEEE library */
|
|
const FloatRoundMode ieee_rm[4] = {
|
|
float_round_nearest_even,
|
|
float_round_to_zero,
|
|
float_round_up,
|
|
float_round_down
|
|
};
|
|
|
|
void cpu_mips_restore_fp_status(CPUMIPSState *env)
|
|
{
|
|
restore_fp_status(env);
|
|
}
|
|
|
|
const char fregnames[32][4] = {
|
|
"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
|
|
"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",
|
|
"f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",
|
|
"f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",
|
|
};
|