Handling a pending signal calls _hurd_setup_sighandler() once again after the
initial signal handling. In this case a pointer to the previous sigcontext is
available to supply the interrupted thread's original basic state, fpu state
and fpu XSTATE. The original XSTATE was not being preserved by the pending
signal but instead overwritten with the active XSTATE. XSTATE register values
modified by the signal handling code could therefore be wrongly propogated back
to the interrupted user code.
---
sysdeps/mach/hurd/i386/bits/sigcontext.h | 1 +
sysdeps/mach/hurd/x86/trampoline.c | 69 ++++++++++++++--------
sysdeps/mach/hurd/x86_64/bits/sigcontext.h | 1 +
3 files changed, 47 insertions(+), 24 deletions(-)
diff --git a/sysdeps/mach/hurd/i386/bits/sigcontext.h
b/sysdeps/mach/hurd/i386/bits/sigcontext.h
index eefc5bbeb8..0e12e26da9 100644
--- a/sysdeps/mach/hurd/i386/bits/sigcontext.h
+++ b/sysdeps/mach/hurd/i386/bits/sigcontext.h
@@ -90,6 +90,7 @@ struct sigcontext
int sc_fpexcsr; /* FPSR including exception bits. */
struct i386_xfloat_state *xstate;
+ size_t xstate_size;
};
/* Traditional BSD names for some members. */
diff --git a/sysdeps/mach/hurd/x86/trampoline.c
b/sysdeps/mach/hurd/x86/trampoline.c
index d1c30fbb49..71bf61b0da 100644
--- a/sysdeps/mach/hurd/x86/trampoline.c
+++ b/sysdeps/mach/hurd/x86/trampoline.c
@@ -151,9 +151,9 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const
struct sigaction *action
ucontext_t ucontext;
siginfo_t siginfo;
#ifdef __x86_64__
- char _pad2[56];
+ char _pad2[48];
#else
- char _pad2[20];
+ char _pad2[16];
#endif
char xstate[];
/* Don't add anything after xstate, as it's dynamically
@@ -170,29 +170,32 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const
struct sigaction *action
/* We have a previous sigcontext that sigreturn was about
to restore when another signal arrived. We will just base
our setup on that. */
- if (! _hurdsig_catch_memory_fault (ss->context))
{
memcpy (&state->basic, &ss->context->sc_i386_thread_state,
sizeof (state->basic));
memcpy (&state->fpu, &ss->context->sc_i386_float_state,
sizeof (state->fpu));
state->set |= (1 << i386_REGS_SEGS_STATE) | (1 << i386_FLOAT_STATE);
+
+ xstate_size = ss->context->xstate_size;
}
}
-
- if (! machine_get_basic_state (ss->thread, state))
- return NULL;
-
- /* Initialize the size of the CPU extended state, to be saved during
- * signal handling */
+ else
+ {
+ /* Initialize the size of the CPU extended state, to be saved during
+ * signal handling */
#ifdef i386_XFLOAT_STATE
- _Static_assert ((sizeof(*stackframe) + sizeof(struct i386_xfloat_state)) %
64 == 0,
- "stackframe size must be multiple of 64-byte minus "
- "sizeof(struct i386_xfloat_state), please adjust _pad2");
+ _Static_assert ((sizeof(*stackframe) + sizeof(struct i386_xfloat_state))
% 64 == 0,
+ "stackframe size must be multiple of 64-byte minus "
+ "sizeof(struct i386_xfloat_state), please adjust _pad2");
- if (__i386_get_xstate_size(__mach_host_self(), &xstate_size))
+ if (__i386_get_xstate_size(__mach_host_self(), &xstate_size))
#endif
- xstate_size = 0;
+ xstate_size = 0;
+ }
+
+ if (! machine_get_basic_state (ss->thread, state))
+ return NULL;
/* Save the original SP in the gratuitous `esp' slot.
We may need to reset the SP (the `uesp' slot) to avoid clobbering an
@@ -279,33 +282,51 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const
struct sigaction *action
memcpy (&scp->sc_i386_thread_state,
&state->basic, sizeof (state->basic));
+ scp->xstate_size = 0;
scp->xstate = NULL;
#ifdef i386_XFLOAT_STATE
if (xstate_size > 0)
{
- mach_msg_type_number_t got = (xstate_size / sizeof (int));
+ if (ss->context != NULL)
+ {
+ assert(ss->context->xstate != NULL);
+
+ /* Copy the xstate preserved at the time of handling the first
+ signal rather than that currently in the FPU. */
+ memcpy(stackframe->xstate, ss->context->xstate, xstate_size);
+ ok = 1;
+ }
+ else
+ {
+ mach_msg_type_number_t got = (xstate_size / sizeof (int));
- ok = (! __thread_get_state (ss->thread, i386_XFLOAT_STATE,
- (thread_state_t) stackframe->xstate,
&got)
- && got == (xstate_size / sizeof (int)));
+ ok = (! __thread_get_state (ss->thread, i386_XFLOAT_STATE,
+ (thread_state_t) stackframe->xstate,
&got)
+ && got == (xstate_size / sizeof (int)));
- if (ok && ((struct i386_xfloat_state*)
stackframe->xstate)->fp_save_kind > 5)
- /* We support up to XSAVES */
- ok = 0;
+ if (ok && ((struct i386_xfloat_state*)
stackframe->xstate)->fp_save_kind > 5)
+ /* We support up to XSAVES */
+ ok = 0;
+ }
- if (ok)
+ if (ok)
{
scp->xstate = (struct i386_xfloat_state*) stackframe->xstate;
+ scp->xstate_size = xstate_size;
assert((uintptr_t)scp->xstate->hw_state % 64 == 0);
}
- }
+ }
else
#endif
ok = 0;
if (!ok)
{
/* struct sigcontext is laid out so that starting at sc_fpkind mimics
- a struct i386_float_state. */
+ a struct i386_float_state. In the event that we are processing a
+ previous sigcontext (ss->context != NULL) 'state' correctly contains
+ the FPU state saved from the previous handler (see memcpy above)
+ rather than that currently in the FPU */
+
_Static_assert (offsetof (struct sigcontext, sc_i386_float_state)
% __alignof__ (struct i386_float_state) == 0,
"sc_i386_float_state layout mismatch");
diff --git a/sysdeps/mach/hurd/x86_64/bits/sigcontext.h
b/sysdeps/mach/hurd/x86_64/bits/sigcontext.h
index 94061e7a91..770523949c 100644
--- a/sysdeps/mach/hurd/x86_64/bits/sigcontext.h
+++ b/sysdeps/mach/hurd/x86_64/bits/sigcontext.h
@@ -98,6 +98,7 @@ struct sigcontext
int sc_fpexcsr; /* FPSR including exception bits. */
struct i386_xfloat_state *xstate;
+ size_t xstate_size;
};
/* Traditional BSD names for some members. */
--
2.47.3
