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>
/* You must call prom_init() before using any of the library services,
* preferably as early as possible. Pass it the romvec pointer.
*/
-void prom_init(void *cif_handler, void *cif_stack);
+void prom_init(void *cif_handler);
+void prom_init_report(void);
/* Boot argument acquisition, returns the boot command line string. */
char *prom_getbootargs(void);
#endif
#ifdef CONFIG_SPARC64
+void __init start_early_boot(void);
+
/* unaligned_64.c */
int handle_ldf_stq(u32 insn, struct pt_regs *regs);
void handle_ld_nf(u32 insn, struct pt_regs *regs);
extern struct pause_patch_entry __pause_3insn_patch,
__pause_3insn_patch_end;
-void __init per_cpu_patch(void);
void sun4v_patch_1insn_range(struct sun4v_1insn_patch_entry *,
struct sun4v_1insn_patch_entry *);
void sun4v_patch_2insn_range(struct sun4v_2insn_patch_entry *,
struct sun4v_2insn_patch_entry *);
-void __init sun4v_patch(void);
-void __init boot_cpu_id_too_large(int cpu);
extern unsigned int dcache_parity_tl1_occurred;
extern unsigned int icache_parity_tl1_occurred;
sethi %hi(init_thread_union), %g6
or %g6, %lo(init_thread_union), %g6
ldx [%g6 + TI_TASK], %g4
- mov %sp, %l6
wr %g0, ASI_P, %asi
mov 1, %g1
sllx %g1, THREAD_SHIFT, %g1
sub %g1, (STACKFRAME_SZ + STACK_BIAS), %g1
add %g6, %g1, %sp
- mov 0, %fp
/* Set per-cpu pointer initially to zero, this makes
* the boot-cpu use the in-kernel-image per-cpu areas
nop
#endif
- mov %l6, %o1 ! OpenPROM stack
call prom_init
mov %l7, %o0 ! OpenPROM cif handler
- /* Initialize current_thread_info()->cpu as early as possible.
- * In order to do that accurately we have to patch up the get_cpuid()
- * assembler sequences. And that, in turn, requires that we know
- * if we are on a Starfire box or not. While we're here, patch up
- * the sun4v sequences as well.
+ /* To create a one-register-window buffer between the kernel's
+ * initial stack and the last stack frame we use from the firmware,
+ * do the rest of the boot from a C helper function.
*/
- call check_if_starfire
- nop
- call per_cpu_patch
- nop
- call sun4v_patch
- nop
-
-#ifdef CONFIG_SMP
- call hard_smp_processor_id
- nop
- cmp %o0, NR_CPUS
- blu,pt %xcc, 1f
- nop
- call boot_cpu_id_too_large
- nop
- /* Not reached... */
-
-1:
-#else
- mov 0, %o0
-#endif
- sth %o0, [%g6 + TI_CPU]
-
- call prom_init_report
- nop
-
- /* Off we go.... */
- call start_kernel
+ call start_early_boot
nop
/* Not reached... */
sllx %g5, THREAD_SHIFT, %g5
sub %g5, (STACKFRAME_SZ + STACK_BIAS), %g5
add %g6, %g5, %sp
- mov 0, %fp
call init_irqwork_curcpu
nop
#include <linux/cpu.h>
#include <linux/initrd.h>
#include <linux/module.h>
+#include <linux/start_kernel.h>
#include <asm/io.h>
#include <asm/processor.h>
static struct pt_regs fake_swapper_regs = { { 0, }, 0, 0, 0, 0 };
-void __init per_cpu_patch(void)
+static void __init per_cpu_patch(void)
{
struct cpuid_patch_entry *p;
unsigned long ver;
}
}
-void __init sun4v_patch(void)
+static void __init sun4v_patch(void)
{
extern void sun4v_hvapi_init(void);
}
}
-#ifdef CONFIG_SMP
-void __init boot_cpu_id_too_large(int cpu)
+void __init start_early_boot(void)
{
- prom_printf("Serious problem, boot cpu id (%d) >= NR_CPUS (%d)\n",
- cpu, NR_CPUS);
- prom_halt();
+ int cpu;
+
+ check_if_starfire();
+ per_cpu_patch();
+ sun4v_patch();
+
+ cpu = hard_smp_processor_id();
+ if (cpu >= NR_CPUS) {
+ prom_printf("Serious problem, boot cpu id (%d) >= NR_CPUS (%d)\n",
+ cpu, NR_CPUS);
+ prom_halt();
+ }
+ current_thread_info()->cpu = cpu;
+
+ prom_init_report();
+ start_kernel();
}
-#endif
/* On Ultra, we support all of the v8 capabilities. */
unsigned long sparc64_elf_hwcap = (HWCAP_SPARC_FLUSH | HWCAP_SPARC_STBAR |
brnz,pn %g1, 1b
nop
- sethi %hi(p1275buf), %g2
- or %g2, %lo(p1275buf), %g2
- ldx [%g2 + 0x10], %l2
- add %l2, -(192 + 128), %sp
+ /* Get onto temporary stack which will be in the locked
+ * kernel image.
+ */
+ sethi %hi(tramp_stack), %g1
+ or %g1, %lo(tramp_stack), %g1
+ add %g1, TRAMP_STACK_SIZE, %g1
+ sub %g1, STACKFRAME_SZ + STACK_BIAS + 256, %sp
flushw
/* Setup the loop variables:
sllx %g5, THREAD_SHIFT, %g5
sub %g5, (STACKFRAME_SZ + STACK_BIAS), %g5
add %g6, %g5, %sp
- mov 0, %fp
rdpr %pstate, %o1
or %o1, PSTATE_IE, %o1
.text
.globl prom_cif_direct
prom_cif_direct:
+ save %sp, -192, %sp
sethi %hi(p1275buf), %o1
or %o1, %lo(p1275buf), %o1
- ldx [%o1 + 0x0010], %o2 ! prom_cif_stack
- save %o2, -192, %sp
- ldx [%i1 + 0x0008], %l2 ! prom_cif_handler
+ ldx [%o1 + 0x0008], %l2 ! prom_cif_handler
mov %g4, %l0
mov %g5, %l1
mov %g6, %l3
* It gets passed the pointer to the PROM vector.
*/
-extern void prom_cif_init(void *, void *);
+extern void prom_cif_init(void *);
-void __init prom_init(void *cif_handler, void *cif_stack)
+void __init prom_init(void *cif_handler)
{
phandle node;
- prom_cif_init(cif_handler, cif_stack);
+ prom_cif_init(cif_handler);
prom_chosen_node = prom_finddevice(prom_chosen_path);
if (!prom_chosen_node || (s32)prom_chosen_node == -1)
struct {
long prom_callback; /* 0x00 */
void (*prom_cif_handler)(long *); /* 0x08 */
- unsigned long prom_cif_stack; /* 0x10 */
} p1275buf;
extern void prom_world(int);
void prom_cif_init(void *cif_handler, void *cif_stack)
{
p1275buf.prom_cif_handler = (void (*)(long *))cif_handler;
- p1275buf.prom_cif_stack = (unsigned long)cif_stack;
}
git.openpandora.org / pandora-kernel.git / commitdiff