[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PATCH for-5.2 2/3] linux-user/sparc: Correct set/get_context handling o
From: |
Peter Maydell |
Subject: |
[PATCH for-5.2 2/3] linux-user/sparc: Correct set/get_context handling of fp and i7 |
Date: |
Thu, 5 Nov 2020 21:23:13 +0000 |
Because QEMU's user-mode emulation just directly accesses guest CPU
state, for SPARC the guest register window state is not the same in
the sparc64_get_context() and sparc64_set_context() functions as it
is for the real kernel's versions of those functions. Specifically,
for the kernel it has saved the user space state such that the O*
registers go into a pt_regs struct as UREG_I*, and the I* registers
have been spilled onto the userspace stack. For QEMU, we haven't
done that, so the guest's O* registers are still in WREG_O* and the
I* registers in WREG_I*.
The code was already accessing the O* registers correctly for QEMU,
but had copied the kernel code for accessing the I* registers off the
userspace stack. Replace this with direct accesses to fp and i7 in
the CPU state, and add a comment explaining why we differ from the
kernel code here.
This fix is sufficient to get bash to a shell prompt.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
I'm really pretty unsure about our handling of SPARC register
windows here. This fix works, but should we instead be
ensuring that the flush_windows() call cpu_loop() does
before handling this trap has written the I* regs to the
stack ???
---
linux-user/sparc/signal.c | 47 ++++++++++++++++++---------------------
1 file changed, 22 insertions(+), 25 deletions(-)
diff --git a/linux-user/sparc/signal.c b/linux-user/sparc/signal.c
index 57ea1593bfc..c315704b389 100644
--- a/linux-user/sparc/signal.c
+++ b/linux-user/sparc/signal.c
@@ -403,7 +403,6 @@ void sparc64_set_context(CPUSPARCState *env)
struct target_ucontext *ucp;
target_mc_gregset_t *grp;
abi_ulong pc, npc, tstate;
- abi_ulong fp, i7, w_addr;
unsigned int i;
ucp_addr = env->regwptr[WREG_O0];
@@ -447,6 +446,15 @@ void sparc64_set_context(CPUSPARCState *env)
__get_user(env->gregs[5], (&(*grp)[SPARC_MC_G5]));
__get_user(env->gregs[6], (&(*grp)[SPARC_MC_G6]));
__get_user(env->gregs[7], (&(*grp)[SPARC_MC_G7]));
+
+ /*
+ * Note that unlike the kernel, we didn't need to mess with the
+ * guest register window state to save it into a pt_regs to run
+ * the kernel. So for us the guest's O regs are still in WREG_O*
+ * (unlike the kernel which has put them in UREG_I* in a pt_regs)
+ * and the fp and i7 are still in WREG_I6 and WREG_I7 and don't
+ * need to be written back to userspace memory.
+ */
__get_user(env->regwptr[WREG_O0], (&(*grp)[SPARC_MC_O0]));
__get_user(env->regwptr[WREG_O1], (&(*grp)[SPARC_MC_O1]));
__get_user(env->regwptr[WREG_O2], (&(*grp)[SPARC_MC_O2]));
@@ -456,18 +464,9 @@ void sparc64_set_context(CPUSPARCState *env)
__get_user(env->regwptr[WREG_O6], (&(*grp)[SPARC_MC_O6]));
__get_user(env->regwptr[WREG_O7], (&(*grp)[SPARC_MC_O7]));
- __get_user(fp, &(ucp->tuc_mcontext.mc_fp));
- __get_user(i7, &(ucp->tuc_mcontext.mc_i7));
+ __get_user(env->regwptr[WREG_FP], &(ucp->tuc_mcontext.mc_fp));
+ __get_user(env->regwptr[WREG_I7], &(ucp->tuc_mcontext.mc_i7));
- w_addr = TARGET_STACK_BIAS + env->regwptr[WREG_O6];
- if (put_user(fp, w_addr + offsetof(struct target_reg_window, ins[6]),
- abi_ulong) != 0) {
- goto do_sigsegv;
- }
- if (put_user(i7, w_addr + offsetof(struct target_reg_window, ins[7]),
- abi_ulong) != 0) {
- goto do_sigsegv;
- }
/* FIXME this does not match how the kernel handles the FPU in
* its sparc64_set_context implementation. In particular the FPU
* is only restored if fenab is non-zero in:
@@ -501,7 +500,6 @@ void sparc64_get_context(CPUSPARCState *env)
struct target_ucontext *ucp;
target_mc_gregset_t *grp;
target_mcontext_t *mcp;
- abi_ulong fp, i7, w_addr;
int err;
unsigned int i;
target_sigset_t target_set;
@@ -553,6 +551,15 @@ void sparc64_get_context(CPUSPARCState *env)
__put_user(env->gregs[5], &((*grp)[SPARC_MC_G5]));
__put_user(env->gregs[6], &((*grp)[SPARC_MC_G6]));
__put_user(env->gregs[7], &((*grp)[SPARC_MC_G7]));
+
+ /*
+ * Note that unlike the kernel, we didn't need to mess with the
+ * guest register window state to save it into a pt_regs to run
+ * the kernel. So for us the guest's O regs are still in WREG_O*
+ * (unlike the kernel which has put them in UREG_I* in a pt_regs)
+ * and the fp and i7 are still in WREG_I6 and WREG_I7 and don't
+ * need to be fished out of userspace memory.
+ */
__put_user(env->regwptr[WREG_O0], &((*grp)[SPARC_MC_O0]));
__put_user(env->regwptr[WREG_O1], &((*grp)[SPARC_MC_O1]));
__put_user(env->regwptr[WREG_O2], &((*grp)[SPARC_MC_O2]));
@@ -562,18 +569,8 @@ void sparc64_get_context(CPUSPARCState *env)
__put_user(env->regwptr[WREG_O6], &((*grp)[SPARC_MC_O6]));
__put_user(env->regwptr[WREG_O7], &((*grp)[SPARC_MC_O7]));
- w_addr = TARGET_STACK_BIAS + env->regwptr[WREG_O6];
- fp = i7 = 0;
- if (get_user(fp, w_addr + offsetof(struct target_reg_window, ins[6]),
- abi_ulong) != 0) {
- goto do_sigsegv;
- }
- if (get_user(i7, w_addr + offsetof(struct target_reg_window, ins[7]),
- abi_ulong) != 0) {
- goto do_sigsegv;
- }
- __put_user(fp, &(mcp->mc_fp));
- __put_user(i7, &(mcp->mc_i7));
+ __put_user(env->regwptr[WREG_FP], &(mcp->mc_fp));
+ __put_user(env->regwptr[WREG_I7], &(mcp->mc_i7));
{
uint32_t *dst = ucp->tuc_mcontext.mc_fpregs.mcfpu_fregs.sregs;
--
2.20.1