From 5c2ffce1e9496477720966e70d79f2da3e4b84e6 Mon Sep 17 00:00:00 2001 From: Anton Ivanov Date: Fri, 4 Jan 2019 15:38:21 +0000 Subject: um: Revert to using stack for pt_regs in signal handling Reverts commit b6024b21fec8367ef961a771cc9dde31f1831965 and adjusts default stack sizing to cope with larger size of floating point save registers on the newer Intel CPUs. b6024b21fec8367ef961a771cc9dde31f1831965 replaced storing the register state on the stack with kmalloc-ed storage. That has a number of issues and a panic if that fails. 1. kmalloc/ATOMIC can fail. There was a latent hard crash in all interrupt and fault handling as a result. 2. kmalloc in the interrupt path introduces a considerable performance penalty for networking ~ 14% on iperf. This commit restores uml to a stable state until a better solution is found. Signed-off-by: Anton Ivanov Signed-off-by: Richard Weinberger --- arch/um/os-Linux/signal.c | 28 ++++++++-------------------- 1 file changed, 8 insertions(+), 20 deletions(-) (limited to 'arch/um/os-Linux/signal.c') 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(®s, mc); + timer_handler(SIGALRM, NULL, ®s); } void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) -- cgit v1.2.3