ef3e035c3a
Meelis Roos reported that kernels built with gcc-4.9 do not boot, we eventually narrowed this down to only impacting machines using UltraSPARC-III and derivitive cpus. The crash happens right when the first user process is spawned: [ 54.451346] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 [ 54.451346] [ 54.571516] CPU: 1 PID: 1 Comm: init Not tainted 3.16.0-rc2-00211-gd7933ab #96 [ 54.666431] Call Trace: [ 54.698453] [0000000000762f8c] panic+0xb0/0x224 [ 54.759071] [000000000045cf68] do_exit+0x948/0x960 [ 54.823123] [000000000042cbc0] fault_in_user_windows+0xe0/0x100 [ 54.902036] [0000000000404ad0] __handle_user_windows+0x0/0x10 [ 54.978662] Press Stop-A (L1-A) to return to the boot prom [ 55.050713] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 Further investigation showed that compiling only per_cpu_patch() with an older compiler fixes the boot. Detailed analysis showed that the function is not being miscompiled by gcc-4.9, but it is using a different register allocation ordering. With the gcc-4.9 compiled function, something during the code patching causes some of the %i* input registers to get corrupted. Perhaps we have a TLB miss path into the firmware that is deep enough to cause a register window spill and subsequent restore when we get back from the TLB miss trap. Let's plug this up by doing two things: 1) Stop using the firmware stack for client interface calls into the firmware. Just use the kernel's stack. 2) As soon as we can, call into a new function "start_early_boot()" to put a one-register-window buffer between the firmware's deepest stack frame and the top-most initial kernel one. Reported-by: Meelis Roos <mroos@linux.ee> Tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: David S. Miller <davem@davemloft.net>
68 lines
1.4 KiB
C
68 lines
1.4 KiB
C
/*
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* Just a place holder.
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*/
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#ifndef _SPARC_SETUP_H
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#define _SPARC_SETUP_H
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#include <linux/interrupt.h>
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#include <uapi/asm/setup.h>
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extern char reboot_command[];
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#ifdef CONFIG_SPARC32
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/* The CPU that was used for booting
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* Only sun4d + leon may have boot_cpu_id != 0
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*/
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extern unsigned char boot_cpu_id;
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extern unsigned long empty_zero_page;
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extern int serial_console;
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static inline int con_is_present(void)
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{
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return serial_console ? 0 : 1;
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}
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/* from irq_32.c */
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extern volatile unsigned char *fdc_status;
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extern char *pdma_vaddr;
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extern unsigned long pdma_size;
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extern volatile int doing_pdma;
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/* This is software state */
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extern char *pdma_base;
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extern unsigned long pdma_areasize;
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int sparc_floppy_request_irq(unsigned int irq, irq_handler_t irq_handler);
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/* setup_32.c */
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extern unsigned long cmdline_memory_size;
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/* devices.c */
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void __init device_scan(void);
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/* unaligned_32.c */
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unsigned long safe_compute_effective_address(struct pt_regs *, unsigned int);
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#endif
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#ifdef CONFIG_SPARC64
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void __init start_early_boot(void);
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/* unaligned_64.c */
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int handle_ldf_stq(u32 insn, struct pt_regs *regs);
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void handle_ld_nf(u32 insn, struct pt_regs *regs);
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/* init_64.c */
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extern atomic_t dcpage_flushes;
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extern atomic_t dcpage_flushes_xcall;
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extern int sysctl_tsb_ratio;
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#endif
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void sun_do_break(void);
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extern int stop_a_enabled;
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extern int scons_pwroff;
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#endif /* _SPARC_SETUP_H */
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