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linux/arch/sparc/kernel/setup_64.c
David S. Miller ef3e035c3a sparc64: Fix register corruption in top-most kernel stack frame during boot. 
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>
2014-10-24 09:52:49 -07:00

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/*
* linux/arch/sparc64/kernel/setup.c
*
* Copyright (C) 1995,1996 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <asm/smp.h>
#include <linux/user.h>
#include <linux/screen_info.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/kdev_t.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/inet.h>
#include <linux/console.h>
#include <linux/root_dev.h>
#include <linux/interrupt.h>
#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>
#include <asm/oplib.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/idprom.h>
#include <asm/head.h>
#include <asm/starfire.h>
#include <asm/mmu_context.h>
#include <asm/timer.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/mmu.h>
#include <asm/ns87303.h>
#include <asm/btext.h>
#include <asm/elf.h>
#include <asm/mdesc.h>
#include <asm/cacheflush.h>
#ifdef CONFIG_IP_PNP
#include <net/ipconfig.h>
#endif
#include "entry.h"
#include "kernel.h"
/* Used to synchronize accesses to NatSemi SUPER I/O chip configure
* operations in asm/ns87303.h
*/
DEFINE_SPINLOCK(ns87303_lock);
EXPORT_SYMBOL(ns87303_lock);
struct screen_info screen_info = {
0, 0, /* orig-x, orig-y */
0, /* unused */
0, /* orig-video-page */
0, /* orig-video-mode */
128, /* orig-video-cols */
0, 0, 0, /* unused, ega_bx, unused */
54, /* orig-video-lines */
0, /* orig-video-isVGA */
16 /* orig-video-points */
};
static void
prom_console_write(struct console *con, const char *s, unsigned n)
{
prom_write(s, n);
}
/* Exported for mm/init.c:paging_init. */
unsigned long cmdline_memory_size = 0;
static struct console prom_early_console = {
.name = "earlyprom",
.write = prom_console_write,
.flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
.index = -1,
};
/*
* Process kernel command line switches that are specific to the
* SPARC or that require special low-level processing.
*/
static void __init process_switch(char c)
{
switch (c) {
case 'd':
case 's':
break;
case 'h':
prom_printf("boot_flags_init: Halt!\n");
prom_halt();
break;
case 'p':
prom_early_console.flags &= ~CON_BOOT;
break;
case 'P':
/* Force UltraSPARC-III P-Cache on. */
if (tlb_type != cheetah) {
printk("BOOT: Ignoring P-Cache force option.\n");
break;
}
cheetah_pcache_forced_on = 1;
add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
cheetah_enable_pcache();
break;
default:
printk("Unknown boot switch (-%c)\n", c);
break;
}
}
static void __init boot_flags_init(char *commands)
{
while (*commands) {
/* Move to the start of the next "argument". */
while (*commands && *commands == ' ')
commands++;
/* Process any command switches, otherwise skip it. */
if (*commands == '\0')
break;
if (*commands == '-') {
commands++;
while (*commands && *commands != ' ')
process_switch(*commands++);
continue;
}
if (!strncmp(commands, "mem=", 4))
cmdline_memory_size = memparse(commands + 4, &commands);
while (*commands && *commands != ' ')
commands++;
}
}
extern unsigned short root_flags;
extern unsigned short root_dev;
extern unsigned short ram_flags;
#define RAMDISK_IMAGE_START_MASK 0x07FF
#define RAMDISK_PROMPT_FLAG 0x8000
#define RAMDISK_LOAD_FLAG 0x4000
extern int root_mountflags;
char reboot_command[COMMAND_LINE_SIZE];
static struct pt_regs fake_swapper_regs = { { 0, }, 0, 0, 0, 0 };
static void __init per_cpu_patch(void)
{
struct cpuid_patch_entry *p;
unsigned long ver;
int is_jbus;
if (tlb_type == spitfire && !this_is_starfire)
return;
is_jbus = 0;
if (tlb_type != hypervisor) {
__asm__ ("rdpr %%ver, %0" : "=r" (ver));
is_jbus = ((ver >> 32UL) == __JALAPENO_ID ||
(ver >> 32UL) == __SERRANO_ID);
}
p = &__cpuid_patch;
while (p < &__cpuid_patch_end) {
unsigned long addr = p->addr;
unsigned int *insns;
switch (tlb_type) {
case spitfire:
insns = &p->starfire[0];
break;
case cheetah:
case cheetah_plus:
if (is_jbus)
insns = &p->cheetah_jbus[0];
else
insns = &p->cheetah_safari[0];
break;
case hypervisor:
insns = &p->sun4v[0];
break;
default:
prom_printf("Unknown cpu type, halting.\n");
prom_halt();
}
*(unsigned int *) (addr + 0) = insns[0];
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 0));
*(unsigned int *) (addr + 4) = insns[1];
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 4));
*(unsigned int *) (addr + 8) = insns[2];
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 8));
*(unsigned int *) (addr + 12) = insns[3];
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 12));
p++;
}
}
void sun4v_patch_1insn_range(struct sun4v_1insn_patch_entry *start,
struct sun4v_1insn_patch_entry *end)
{
while (start < end) {
unsigned long addr = start->addr;
*(unsigned int *) (addr + 0) = start->insn;
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 0));
start++;
}
}
void sun4v_patch_2insn_range(struct sun4v_2insn_patch_entry *start,
struct sun4v_2insn_patch_entry *end)
{
while (start < end) {
unsigned long addr = start->addr;
*(unsigned int *) (addr + 0) = start->insns[0];
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 0));
*(unsigned int *) (addr + 4) = start->insns[1];
wmb();
__asm__ __volatile__("flush %0" : : "r" (addr + 4));
start++;
}
}
static void __init sun4v_patch(void)
{
extern void sun4v_hvapi_init(void);
if (tlb_type != hypervisor)
return;
sun4v_patch_1insn_range(&__sun4v_1insn_patch,
&__sun4v_1insn_patch_end);
sun4v_patch_2insn_range(&__sun4v_2insn_patch,
&__sun4v_2insn_patch_end);
sun4v_hvapi_init();
}
static void __init popc_patch(void)
{
struct popc_3insn_patch_entry *p3;
struct popc_6insn_patch_entry *p6;
p3 = &__popc_3insn_patch;
while (p3 < &__popc_3insn_patch_end) {
unsigned long i, addr = p3->addr;
for (i = 0; i < 3; i++) {
*(unsigned int *) (addr + (i * 4)) = p3->insns[i];
wmb();
__asm__ __volatile__("flush %0"
: : "r" (addr + (i * 4)));
}
p3++;
}
p6 = &__popc_6insn_patch;
while (p6 < &__popc_6insn_patch_end) {
unsigned long i, addr = p6->addr;
for (i = 0; i < 6; i++) {
*(unsigned int *) (addr + (i * 4)) = p6->insns[i];
wmb();
__asm__ __volatile__("flush %0"
: : "r" (addr + (i * 4)));
}
p6++;
}
}
static void __init pause_patch(void)
{
struct pause_patch_entry *p;
p = &__pause_3insn_patch;
while (p < &__pause_3insn_patch_end) {
unsigned long i, addr = p->addr;
for (i = 0; i < 3; i++) {
*(unsigned int *) (addr + (i * 4)) = p->insns[i];
wmb();
__asm__ __volatile__("flush %0"
: : "r" (addr + (i * 4)));
}
p++;
}
}
void __init start_early_boot(void)
{
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();
}
/* On Ultra, we support all of the v8 capabilities. */
unsigned long sparc64_elf_hwcap = (HWCAP_SPARC_FLUSH | HWCAP_SPARC_STBAR |
HWCAP_SPARC_SWAP | HWCAP_SPARC_MULDIV |
HWCAP_SPARC_V9);
EXPORT_SYMBOL(sparc64_elf_hwcap);
static const char *hwcaps[] = {
"flush", "stbar", "swap", "muldiv", "v9",
"ultra3", "blkinit", "n2",
/* These strings are as they appear in the machine description
* 'hwcap-list' property for cpu nodes.
*/
"mul32", "div32", "fsmuld", "v8plus", "popc", "vis", "vis2",
"ASIBlkInit", "fmaf", "vis3", "hpc", "random", "trans", "fjfmau",
"ima", "cspare", "pause", "cbcond",
};
static const char *crypto_hwcaps[] = {
"aes", "des", "kasumi", "camellia", "md5", "sha1", "sha256",
"sha512", "mpmul", "montmul", "montsqr", "crc32c",
};
void cpucap_info(struct seq_file *m)
{
unsigned long caps = sparc64_elf_hwcap;
int i, printed = 0;
seq_puts(m, "cpucaps\t\t: ");
for (i = 0; i < ARRAY_SIZE(hwcaps); i++) {
unsigned long bit = 1UL << i;
if (caps & bit) {
seq_printf(m, "%s%s",
printed ? "," : "", hwcaps[i]);
printed++;
}
}
if (caps & HWCAP_SPARC_CRYPTO) {
unsigned long cfr;
__asm__ __volatile__("rd %%asr26, %0" : "=r" (cfr));
for (i = 0; i < ARRAY_SIZE(crypto_hwcaps); i++) {
unsigned long bit = 1UL << i;
if (cfr & bit) {
seq_printf(m, "%s%s",
printed ? "," : "", crypto_hwcaps[i]);
printed++;
}
}
}
seq_putc(m, '\n');
}
static void __init report_one_hwcap(int *printed, const char *name)
{
if ((*printed) == 0)
printk(KERN_INFO "CPU CAPS: [");
printk(KERN_CONT "%s%s",
(*printed) ? "," : "", name);
if (++(*printed) == 8) {
printk(KERN_CONT "]\n");
*printed = 0;
}
}
static void __init report_crypto_hwcaps(int *printed)
{
unsigned long cfr;
int i;
__asm__ __volatile__("rd %%asr26, %0" : "=r" (cfr));
for (i = 0; i < ARRAY_SIZE(crypto_hwcaps); i++) {
unsigned long bit = 1UL << i;
if (cfr & bit)
report_one_hwcap(printed, crypto_hwcaps[i]);
}
}
static void __init report_hwcaps(unsigned long caps)
{
int i, printed = 0;
for (i = 0; i < ARRAY_SIZE(hwcaps); i++) {
unsigned long bit = 1UL << i;
if (caps & bit)
report_one_hwcap(&printed, hwcaps[i]);
}
if (caps & HWCAP_SPARC_CRYPTO)
report_crypto_hwcaps(&printed);
if (printed != 0)
printk(KERN_CONT "]\n");
}
static unsigned long __init mdesc_cpu_hwcap_list(void)
{
struct mdesc_handle *hp;
unsigned long caps = 0;
const char *prop;
int len;
u64 pn;
hp = mdesc_grab();
if (!hp)
return 0;
pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
if (pn == MDESC_NODE_NULL)
goto out;
prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
if (!prop)
goto out;
while (len) {
int i, plen;
for (i = 0; i < ARRAY_SIZE(hwcaps); i++) {
unsigned long bit = 1UL << i;
if (!strcmp(prop, hwcaps[i])) {
caps |= bit;
break;
}
}
for (i = 0; i < ARRAY_SIZE(crypto_hwcaps); i++) {
if (!strcmp(prop, crypto_hwcaps[i]))
caps |= HWCAP_SPARC_CRYPTO;
}
plen = strlen(prop) + 1;
prop += plen;
len -= plen;
}
out:
mdesc_release(hp);
return caps;
}
/* This yields a mask that user programs can use to figure out what
* instruction set this cpu supports.
*/
static void __init init_sparc64_elf_hwcap(void)
{
unsigned long cap = sparc64_elf_hwcap;
unsigned long mdesc_caps;
if (tlb_type == cheetah || tlb_type == cheetah_plus)
cap |= HWCAP_SPARC_ULTRA3;
else if (tlb_type == hypervisor) {
if (sun4v_chip_type == SUN4V_CHIP_NIAGARA1 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA2 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
sun4v_chip_type == SUN4V_CHIP_SPARC64X)
cap |= HWCAP_SPARC_BLKINIT;
if (sun4v_chip_type == SUN4V_CHIP_NIAGARA2 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
sun4v_chip_type == SUN4V_CHIP_SPARC64X)
cap |= HWCAP_SPARC_N2;
}
cap |= (AV_SPARC_MUL32 | AV_SPARC_DIV32 | AV_SPARC_V8PLUS);
mdesc_caps = mdesc_cpu_hwcap_list();
if (!mdesc_caps) {
if (tlb_type == spitfire)
cap |= AV_SPARC_VIS;
if (tlb_type == cheetah || tlb_type == cheetah_plus)
cap |= AV_SPARC_VIS | AV_SPARC_VIS2;
if (tlb_type == cheetah_plus) {
unsigned long impl, ver;
__asm__ __volatile__("rdpr %%ver, %0" : "=r" (ver));
impl = ((ver >> 32) & 0xffff);
if (impl == PANTHER_IMPL)
cap |= AV_SPARC_POPC;
}
if (tlb_type == hypervisor) {
if (sun4v_chip_type == SUN4V_CHIP_NIAGARA1)
cap |= AV_SPARC_ASI_BLK_INIT;
if (sun4v_chip_type == SUN4V_CHIP_NIAGARA2 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
sun4v_chip_type == SUN4V_CHIP_SPARC64X)
cap |= (AV_SPARC_VIS | AV_SPARC_VIS2 |
AV_SPARC_ASI_BLK_INIT |
AV_SPARC_POPC);
if (sun4v_chip_type == SUN4V_CHIP_NIAGARA3 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA4 ||
sun4v_chip_type == SUN4V_CHIP_NIAGARA5 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M6 ||
sun4v_chip_type == SUN4V_CHIP_SPARC_M7 ||
sun4v_chip_type == SUN4V_CHIP_SPARC64X)
cap |= (AV_SPARC_VIS3 | AV_SPARC_HPC |
AV_SPARC_FMAF);
}
}
sparc64_elf_hwcap = cap | mdesc_caps;
report_hwcaps(sparc64_elf_hwcap);
if (sparc64_elf_hwcap & AV_SPARC_POPC)
popc_patch();
if (sparc64_elf_hwcap & AV_SPARC_PAUSE)
pause_patch();
}
void __init setup_arch(char **cmdline_p)
{
/* Initialize PROM console and command line. */
*cmdline_p = prom_getbootargs();
strlcpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
parse_early_param();
boot_flags_init(*cmdline_p);
#ifdef CONFIG_EARLYFB
if (btext_find_display())
#endif
register_console(&prom_early_console);
if (tlb_type == hypervisor)
printk("ARCH: SUN4V\n");
else
printk("ARCH: SUN4U\n");
#ifdef CONFIG_DUMMY_CONSOLE
conswitchp = &dummy_con;
#endif
idprom_init();
if (!root_flags)
root_mountflags &= ~MS_RDONLY;
ROOT_DEV = old_decode_dev(root_dev);
#ifdef CONFIG_BLK_DEV_RAM
rd_image_start = ram_flags & RAMDISK_IMAGE_START_MASK;
rd_prompt = ((ram_flags & RAMDISK_PROMPT_FLAG) != 0);
rd_doload = ((ram_flags & RAMDISK_LOAD_FLAG) != 0);
#endif
task_thread_info(&init_task)->kregs = &fake_swapper_regs;
#ifdef CONFIG_IP_PNP
if (!ic_set_manually) {
phandle chosen = prom_finddevice("/chosen");
u32 cl, sv, gw;
cl = prom_getintdefault (chosen, "client-ip", 0);
sv = prom_getintdefault (chosen, "server-ip", 0);
gw = prom_getintdefault (chosen, "gateway-ip", 0);
if (cl && sv) {
ic_myaddr = cl;
ic_servaddr = sv;
if (gw)
ic_gateway = gw;
#if defined(CONFIG_IP_PNP_BOOTP) || defined(CONFIG_IP_PNP_RARP)
ic_proto_enabled = 0;
#endif
}
}
#endif
/* Get boot processor trap_block[] setup. */
init_cur_cpu_trap(current_thread_info());
paging_init();
init_sparc64_elf_hwcap();
}
extern int stop_a_enabled;
void sun_do_break(void)
{
if (!stop_a_enabled)
return;
prom_printf("\n");
flush_user_windows();
prom_cmdline();
}
EXPORT_SYMBOL(sun_do_break);
int stop_a_enabled = 1;
EXPORT_SYMBOL(stop_a_enabled);
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