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-rw-r--r--arch/um/Kconfig10
-rw-r--r--arch/um/os-Linux/signal.c28
2 files changed, 15 insertions, 23 deletions
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index ec9711d068b7..41913504a56e 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -142,13 +142,17 @@ config MAGIC_SYSRQ
config KERNEL_STACK_ORDER
int "Kernel stack size order"
- default 1 if 64BIT
- range 1 10 if 64BIT
- default 0 if !64BIT
+ default 2 if 64BIT
+ range 2 10 if 64BIT
+ default 1 if !64BIT
help
This option determines the size of UML kernel stacks. They will
be 1 << order pages. The default is OK unless you're running Valgrind
on UML, in which case, set this to 3.
+ It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
+ older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
+ increase in the size of the state which needs to be saved when handling
+ signals.
config MMAPPER
tristate "iomem emulation driver"
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index bf0acb8aad8b..75b10235d369 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -31,29 +31,23 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
{
- struct uml_pt_regs *r;
+ struct uml_pt_regs r;
int save_errno = errno;
- r = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC);
- if (!r)
- panic("out of memory");
-
- r->is_user = 0;
+ r.is_user = 0;
if (sig == SIGSEGV) {
/* For segfaults, we want the data from the sigcontext. */
- get_regs_from_mc(r, mc);
- GET_FAULTINFO_FROM_MC(r->faultinfo, mc);
+ get_regs_from_mc(&r, mc);
+ GET_FAULTINFO_FROM_MC(r.faultinfo, mc);
}
/* enable signals if sig isn't IRQ signal */
if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM))
unblock_signals();
- (*sig_info[sig])(sig, si, r);
+ (*sig_info[sig])(sig, si, &r);
errno = save_errno;
-
- free(r);
}
/*
@@ -91,17 +85,11 @@ void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
static void timer_real_alarm_handler(mcontext_t *mc)
{
- struct uml_pt_regs *regs;
-
- regs = uml_kmalloc(sizeof(struct uml_pt_regs), UM_GFP_ATOMIC);
- if (!regs)
- panic("out of memory");
+ struct uml_pt_regs regs;
if (mc != NULL)
- get_regs_from_mc(regs, mc);
- timer_handler(SIGALRM, NULL, regs);
-
- free(regs);
+ get_regs_from_mc(&regs, mc);
+ timer_handler(SIGALRM, NULL, &regs);
}
void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)