d6ab9fc745
Before this patch, the TOC code used a pre-allocated stack of 16kb for each possible CPU. That space overhead was the reason why the TOC feature wasn't enabled by default for 32-bit kernels. This patch rewrites the TOC code to use a per-cpu stack. That way we use much less memory now and as such we enable the TOC feature by default on all kernels. Additionally the dump of the registers and the stacktrace wasn't serialized, which led to multiple CPUs printing the stack backtrace at once which rendered the output unreadable. Now the backtraces are nicely serialized by a lock. Signed-off-by: Helge Deller <deller@gmx.de>
126 lines
3.0 KiB
C
126 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/kgdb.h>
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#include <linux/printk.h>
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#include <linux/sched/debug.h>
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#include <linux/delay.h>
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#include <linux/reboot.h>
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#include <asm/pdc.h>
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#include <asm/pdc_chassis.h>
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#include <asm/ldcw.h>
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static unsigned int __aligned(16) toc_lock = 1;
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DEFINE_PER_CPU_PAGE_ALIGNED(char [16384], toc_stack);
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static void toc20_to_pt_regs(struct pt_regs *regs, struct pdc_toc_pim_20 *toc)
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{
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int i;
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regs->gr[0] = (unsigned long)toc->cr[22];
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for (i = 1; i < 32; i++)
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regs->gr[i] = (unsigned long)toc->gr[i];
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for (i = 0; i < 8; i++)
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regs->sr[i] = (unsigned long)toc->sr[i];
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regs->iasq[0] = (unsigned long)toc->cr[17];
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regs->iasq[1] = (unsigned long)toc->iasq_back;
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regs->iaoq[0] = (unsigned long)toc->cr[18];
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regs->iaoq[1] = (unsigned long)toc->iaoq_back;
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regs->sar = (unsigned long)toc->cr[11];
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regs->iir = (unsigned long)toc->cr[19];
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regs->isr = (unsigned long)toc->cr[20];
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regs->ior = (unsigned long)toc->cr[21];
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}
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static void toc11_to_pt_regs(struct pt_regs *regs, struct pdc_toc_pim_11 *toc)
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{
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int i;
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regs->gr[0] = toc->cr[22];
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for (i = 1; i < 32; i++)
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regs->gr[i] = toc->gr[i];
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for (i = 0; i < 8; i++)
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regs->sr[i] = toc->sr[i];
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regs->iasq[0] = toc->cr[17];
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regs->iasq[1] = toc->iasq_back;
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regs->iaoq[0] = toc->cr[18];
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regs->iaoq[1] = toc->iaoq_back;
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regs->sar = toc->cr[11];
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regs->iir = toc->cr[19];
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regs->isr = toc->cr[20];
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regs->ior = toc->cr[21];
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}
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void notrace __noreturn __cold toc_intr(struct pt_regs *regs)
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{
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struct pdc_toc_pim_20 pim_data20;
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struct pdc_toc_pim_11 pim_data11;
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/* verify we wrote regs to the correct stack */
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BUG_ON(regs != (struct pt_regs *)&per_cpu(toc_stack, raw_smp_processor_id()));
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if (boot_cpu_data.cpu_type >= pcxu) {
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if (pdc_pim_toc20(&pim_data20))
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panic("Failed to get PIM data");
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toc20_to_pt_regs(regs, &pim_data20);
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} else {
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if (pdc_pim_toc11(&pim_data11))
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panic("Failed to get PIM data");
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toc11_to_pt_regs(regs, &pim_data11);
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}
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#ifdef CONFIG_KGDB
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nmi_enter();
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if (atomic_read(&kgdb_active) != -1)
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kgdb_nmicallback(raw_smp_processor_id(), regs);
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kgdb_handle_exception(9, SIGTRAP, 0, regs);
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#endif
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/* serialize output, otherwise all CPUs write backtrace at once */
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while (__ldcw(&toc_lock) == 0)
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; /* wait */
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show_regs(regs);
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toc_lock = 1; /* release lock for next CPU */
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if (raw_smp_processor_id() != 0)
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while (1) ; /* all but monarch CPU will wait endless. */
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/* give other CPUs time to show their backtrace */
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mdelay(2000);
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machine_restart("TOC");
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/* should never reach this */
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panic("TOC");
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}
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static __init int setup_toc(void)
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{
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unsigned int csum = 0;
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unsigned long toc_code = (unsigned long)dereference_function_descriptor(toc_handler);
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int i;
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PAGE0->vec_toc = __pa(toc_code) & 0xffffffff;
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#ifdef CONFIG_64BIT
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PAGE0->vec_toc_hi = __pa(toc_code) >> 32;
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#endif
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PAGE0->vec_toclen = toc_handler_size;
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for (i = 0; i < toc_handler_size/4; i++)
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csum += ((u32 *)toc_code)[i];
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toc_handler_csum = -csum;
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pr_info("TOC handler registered\n");
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return 0;
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}
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early_initcall(setup_toc);
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