* Re: [PATCH v3 13/15] powerpc/64s: machine check do not trace real-mode handler
From: Christophe Leroy @ 2020-04-07 5:45 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Cc: Mahesh Salgaonkar, Naveen N . Rao, Ganesh Goudar
In-Reply-To: <20200407051636.648369-14-npiggin@gmail.com>
Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> Rather than notrace annotations throughout a significant part of the
> machine check code across kernel/ pseries/ and powernv/ which can
> easily be broken and is infrequently tested, use paca->ftrace_enabled
> to blanket-disable tracing of the real-mode non-maskable handler.
>
> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> arch/powerpc/kernel/mce.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
> index be7e3f92a7b5..fd90c0eda229 100644
> --- a/arch/powerpc/kernel/mce.c
> +++ b/arch/powerpc/kernel/mce.c
> @@ -16,6 +16,7 @@
> #include <linux/export.h>
> #include <linux/irq_work.h>
> #include <linux/extable.h>
> +#include <linux/ftrace.h>
>
> #include <asm/machdep.h>
> #include <asm/mce.h>
> @@ -571,10 +572,14 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
> *
> * regs->nip and regs->msr contains srr0 and ssr1.
> */
> -long machine_check_early(struct pt_regs *regs)
> +long notrace machine_check_early(struct pt_regs *regs)
> {
> long handled = 0;
> bool nested = in_nmi();
> + u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
> +
> + this_cpu_set_ftrace_enabled(0);
> +
> if (!nested)
> nmi_enter();
>
> @@ -589,6 +594,8 @@ long machine_check_early(struct pt_regs *regs)
> if (!nested)
> nmi_exit();
>
> + this_cpu_set_ftrace_enabled(ftrace_enabled);
> +
> return handled;
> }
>
>
^ permalink raw reply
* Re: [PATCH v3 12/15] powerpc: ftrace_enabled helper
From: Christophe Leroy @ 2020-04-07 5:45 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Cc: Mahesh Salgaonkar, Naveen N . Rao, Ganesh Goudar
In-Reply-To: <20200407051636.648369-13-npiggin@gmail.com>
Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> arch/powerpc/include/asm/ftrace.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
> index f54a08a2cd70..bc76970b6ee5 100644
> --- a/arch/powerpc/include/asm/ftrace.h
> +++ b/arch/powerpc/include/asm/ftrace.h
> @@ -108,9 +108,23 @@ static inline void this_cpu_enable_ftrace(void)
> {
> get_paca()->ftrace_enabled = 1;
> }
> +
> +/* Disable ftrace on this CPU if possible (may not be implemented) */
> +static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled)
> +{
> + get_paca()->ftrace_enabled = ftrace_enabled;
> +}
> +
> +static inline u8 this_cpu_get_ftrace_enabled(void)
> +{
> + return get_paca()->ftrace_enabled;
> +}
> +
> #else /* CONFIG_PPC64 */
> static inline void this_cpu_disable_ftrace(void) { }
> static inline void this_cpu_enable_ftrace(void) { }
> +static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled) { }
> +static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; }
> #endif /* CONFIG_PPC64 */
> #endif /* !__ASSEMBLY__ */
>
>
^ permalink raw reply
* Re: [PATCH v3 05/15] powerpc/pseries/ras: avoid calling rtas_token in NMI paths
From: Christophe Leroy @ 2020-04-07 5:42 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar
In-Reply-To: <20200407051636.648369-6-npiggin@gmail.com>
Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> In the interest of reducing code and possible failures in the
> machine check and system reset paths, grab the "ibm,nmi-interlock"
> token at init time.
>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> arch/powerpc/include/asm/firmware.h | 1 +
> arch/powerpc/platforms/pseries/ras.c | 2 +-
> arch/powerpc/platforms/pseries/setup.c | 14 ++++++++++----
> 3 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/firmware.h b/arch/powerpc/include/asm/firmware.h
> index ca33f4ef6cb4..6003c2e533a0 100644
> --- a/arch/powerpc/include/asm/firmware.h
> +++ b/arch/powerpc/include/asm/firmware.h
> @@ -128,6 +128,7 @@ extern void machine_check_fwnmi(void);
>
> /* This is true if we are using the firmware NMI handler (typically LPAR) */
> extern int fwnmi_active;
> +extern int ibm_nmi_interlock_token;
>
> extern unsigned int __start___fw_ftr_fixup, __stop___fw_ftr_fixup;
>
> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
> index aa6208c8d4f0..972b95ebc867 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -458,7 +458,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
> */
> static void fwnmi_release_errinfo(void)
> {
> - int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
> + int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
> if (ret != 0)
> printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
> }
> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
> index 0c8421dd01ab..dd234095ae4f 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -83,6 +83,7 @@ unsigned long CMO_PageSize = (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K);
> EXPORT_SYMBOL(CMO_PageSize);
>
> int fwnmi_active; /* TRUE if an FWNMI handler is present */
> +int ibm_nmi_interlock_token;
>
> static void pSeries_show_cpuinfo(struct seq_file *m)
> {
> @@ -113,9 +114,14 @@ static void __init fwnmi_init(void)
> struct slb_entry *slb_ptr;
> size_t size;
> #endif
> + int ibm_nmi_register_token;
>
> - int ibm_nmi_register = rtas_token("ibm,nmi-register");
> - if (ibm_nmi_register == RTAS_UNKNOWN_SERVICE)
> + ibm_nmi_register_token = rtas_token("ibm,nmi-register");
> + if (ibm_nmi_register_token == RTAS_UNKNOWN_SERVICE)
> + return;
> +
> + ibm_nmi_interlock_token = rtas_token("ibm,nmi-interlock");
> + if (WARN_ON(ibm_nmi_interlock_token == RTAS_UNKNOWN_SERVICE))
> return;
>
> /* If the kernel's not linked at zero we point the firmware at low
> @@ -123,8 +129,8 @@ static void __init fwnmi_init(void)
> system_reset_addr = __pa(system_reset_fwnmi) - PHYSICAL_START;
> machine_check_addr = __pa(machine_check_fwnmi) - PHYSICAL_START;
>
> - if (0 == rtas_call(ibm_nmi_register, 2, 1, NULL, system_reset_addr,
> - machine_check_addr))
> + if (0 == rtas_call(ibm_nmi_register_token, 2, 1, NULL,
> + system_reset_addr, machine_check_addr))
> fwnmi_active = 1;
>
> /*
>
^ permalink raw reply
* Re: [PATCH v3 08/15] powerpc/pseries/ras: fwnmi sreset should not interlock
From: Christophe Leroy @ 2020-04-07 5:41 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar
In-Reply-To: <20200407051636.648369-9-npiggin@gmail.com>
Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> PAPR does not specify that fwnmi sreset should be interlocked, and
> PowerVM (and therefore now QEMU) do not require it.
>
> These "ibm,nmi-interlock" calls are ignored by firmware, but there
> is a possibility that the sreset could have interrupted a machine
> check and release the machine check's interlock too early, corrupting
> it if another machine check came in.
>
> This is an extremely rare case, but it should be fixed for clarity
> and reducing the code executed in the sreset path. Firmware also
> does not provide error information for the sreset case to look at, so
> remove that comment.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> arch/powerpc/platforms/pseries/ras.c | 46 +++++++++++++++++++---------
> 1 file changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
> index 2c60e2be1bc5..d65bc38bcb8f 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -406,6 +406,20 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
> return (struct rtas_error_log *)local_paca->mce_data_buf;
> }
>
> +static unsigned long *fwnmi_get_savep(struct pt_regs *regs)
> +{
> + unsigned long savep_ra;
> +
> + /* Mask top two bits */
> + savep_ra = regs->gpr[3] & ~(0x3UL << 62);
> + if (!VALID_FWNMI_BUFFER(savep_ra)) {
> + printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
pr_err() ?
> + return NULL;
> + }
> +
> + return __va(savep_ra);
> +}
> +
> /*
> * Get the error information for errors coming through the
> * FWNMI vectors. The pt_regs' r3 will be updated to reflect
> @@ -423,20 +437,14 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
> */
> static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
> {
> - unsigned long savep_ra;
> unsigned long *savep;
> struct rtas_error_log *h;
>
> - /* Mask top two bits */
> - savep_ra = regs->gpr[3] & ~(0x3UL << 62);
> -
> - if (!VALID_FWNMI_BUFFER(savep_ra)) {
> - printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
> + savep = fwnmi_get_savep(regs);
> + if (!savep)
> return NULL;
> - }
>
> - savep = __va(savep_ra);
> - regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
> + regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
Not sure the above line change is needed.
>
> h = (struct rtas_error_log *)&savep[1];
> /* Use the per cpu buffer from paca to store rtas error log */
> @@ -483,11 +491,21 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
> #endif
>
> if (fwnmi_active) {
> - struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
> - if (errhdr) {
> - /* XXX Should look at FWNMI information */
> - }
> - fwnmi_release_errinfo();
> + unsigned long *savep;
> +
> + /*
> + * Firmware (PowerVM and KVM) saves r3 to a save area like
> + * machine check, which is not exactly what PAPR (2.9)
> + * suggests but there is no way to detect otherwise, so this
> + * is the interface now.
> + *
> + * System resets do not save any error log or require an
> + * "ibm,nmi-interlock" rtas call to release.
> + */
> +
> + savep = fwnmi_get_savep(regs);
> + if (savep)
> + regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
> }
>
> if (smp_handle_nmi_ipi(regs))
>
Christophe
^ permalink raw reply
* Re: [PATCH v3 09/15] powerpc/pseries: limit machine check stack to 4GB
From: Christophe Leroy @ 2020-04-07 5:38 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar
In-Reply-To: <20200407051636.648369-10-npiggin@gmail.com>
Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> This allows rtas_args to be put on the machine check stack, which
> avoids a lot of complications with re-entrancy deadlocks.
>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> arch/powerpc/kernel/setup_64.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index 438a9befce41..defe05b6b7a9 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -709,7 +709,7 @@ void __init exc_lvl_early_init(void)
> */
> void __init emergency_stack_init(void)
> {
> - u64 limit;
> + u64 limit, mce_limit;
> unsigned int i;
>
> /*
> @@ -726,7 +726,16 @@ void __init emergency_stack_init(void)
> * initialized in kernel/irq.c. These are initialized here in order
> * to have emergency stacks available as early as possible.
> */
> - limit = min(ppc64_bolted_size(), ppc64_rma_size);
> + limit = mce_limit = min(ppc64_bolted_size(), ppc64_rma_size);
> +
> + /*
> + * Machine check on pseries calls rtas, but can't use the static
> + * rtas_args due to a machine check hitting while the lock is held.
> + * rtas args have to be under 4GB, so the machine check stack is
> + * limited to 4GB so args can be put on stack.
> + */
> + if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > SZ_4G)
> + mce_limit = SZ_4G;
>
> for_each_possible_cpu(i) {
> paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
> @@ -736,7 +745,7 @@ void __init emergency_stack_init(void)
> paca_ptrs[i]->nmi_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
>
> /* emergency stack for machine check exception handling. */
> - paca_ptrs[i]->mc_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
> + paca_ptrs[i]->mc_emergency_sp = alloc_stack(mce_limit, i) + THREAD_SIZE;
> #endif
> }
> }
>
^ permalink raw reply
* Re: [PATCH v3 11/15] powerpc/64s: machine check interrupt update NMI accounting
From: Christophe Leroy @ 2020-04-07 5:37 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar
In-Reply-To: <20200407051636.648369-12-npiggin@gmail.com>
Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> machine_check_early is taken as an NMI, so nmi_enter is used there.
> machine_check_exception is no longer taken as an NMI (it's invoked
> via irq_work in the case a machine check hits in kernel mode), so
> remove the nmi_enter from that case.
Euh ... Is that also the case for PPC32 ?
AFAIK machine_check_exception() is called as an NMI on PPC32.
Christophe
>
> In NMI context, hash faults don't try to refill the hash table, which
> can lead to crashes accessing non-pinned kernel pages. System reset
> still has this potential problem.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> arch/powerpc/kernel/mce.c | 7 +++++++
> arch/powerpc/kernel/process.c | 2 +-
> arch/powerpc/kernel/traps.c | 13 +------------
> 3 files changed, 9 insertions(+), 13 deletions(-)
>
> diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
> index 8077b5fb18a7..be7e3f92a7b5 100644
> --- a/arch/powerpc/kernel/mce.c
> +++ b/arch/powerpc/kernel/mce.c
> @@ -574,6 +574,9 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
> long machine_check_early(struct pt_regs *regs)
> {
> long handled = 0;
> + bool nested = in_nmi();
> + if (!nested)
> + nmi_enter();
>
> hv_nmi_check_nonrecoverable(regs);
>
> @@ -582,6 +585,10 @@ long machine_check_early(struct pt_regs *regs)
> */
> if (ppc_md.machine_check_early)
> handled = ppc_md.machine_check_early(regs);
> +
> + if (!nested)
> + nmi_exit();
> +
> return handled;
> }
>
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 9c21288f8645..44410dd3029f 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1421,7 +1421,7 @@ void show_regs(struct pt_regs * regs)
> pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
> #endif
> #ifdef CONFIG_PPC64
> - pr_cont("IRQMASK: %lx ", regs->softe);
> + pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe, (int)get_paca()->in_nmi, (int)get_paca()->in_mce);
> #endif
> #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> if (MSR_TM_ACTIVE(regs->msr))
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 3fca22276bb1..9f221772eb73 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -823,9 +823,6 @@ int machine_check_generic(struct pt_regs *regs)
> void machine_check_exception(struct pt_regs *regs)
> {
> int recover = 0;
> - bool nested = in_nmi();
> - if (!nested)
> - nmi_enter();
>
> __this_cpu_inc(irq_stat.mce_exceptions);
>
> @@ -851,20 +848,12 @@ void machine_check_exception(struct pt_regs *regs)
> if (check_io_access(regs))
> goto bail;
>
> - if (!nested)
> - nmi_exit();
> -
> die("Machine check", regs, SIGBUS);
>
> +bail:
> /* Must die if the interrupt is not recoverable */
> if (!(regs->msr & MSR_RI))
> nmi_panic(regs, "Unrecoverable Machine check");
> -
> - return;
> -
> -bail:
> - if (!nested)
> - nmi_exit();
> }
>
> void SMIException(struct pt_regs *regs)
>
^ permalink raw reply
* Re: [PATCH] powerpcs: perf: consolidate perf_callchain_user_64 and perf_callchain_user_32
From: Christophe Leroy @ 2020-04-07 5:21 UTC (permalink / raw)
To: Michal Suchanek, linuxppc-dev, Nicholas Piggin
Cc: Mark Rutland, Peter Zijlstra, linux-kernel,
Arnaldo Carvalho de Melo, Alexander Shishkin, Ingo Molnar,
Paul Mackerras, Namhyung Kim, Jiri Olsa
In-Reply-To: <20200406210022.32265-1-msuchanek@suse.de>
Le 06/04/2020 à 23:00, Michal Suchanek a écrit :
> perf_callchain_user_64 and perf_callchain_user_32 are nearly identical.
> Consolidate into one function with thin wrappers.
>
> Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
> arch/powerpc/perf/callchain.h | 24 +++++++++++++++++++++++-
> arch/powerpc/perf/callchain_32.c | 21 ++-------------------
> arch/powerpc/perf/callchain_64.c | 14 ++++----------
> 3 files changed, 29 insertions(+), 30 deletions(-)
>
> diff --git a/arch/powerpc/perf/callchain.h b/arch/powerpc/perf/callchain.h
> index 7a2cb9e1181a..7540bb71cb60 100644
> --- a/arch/powerpc/perf/callchain.h
> +++ b/arch/powerpc/perf/callchain.h
> @@ -2,7 +2,7 @@
> #ifndef _POWERPC_PERF_CALLCHAIN_H
> #define _POWERPC_PERF_CALLCHAIN_H
>
> -int read_user_stack_slow(void __user *ptr, void *buf, int nb);
> +int read_user_stack_slow(const void __user *ptr, void *buf, int nb);
Does the constification of ptr has to be in this patch ?
Wouldn't it be better to have it as a separate patch ?
> void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
> struct pt_regs *regs);
> void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
> @@ -16,4 +16,26 @@ static inline bool invalid_user_sp(unsigned long sp)
> return (!sp || (sp & mask) || (sp > top));
> }
>
> +/*
> + * On 32-bit we just access the address and let hash_page create a
> + * HPTE if necessary, so there is no need to fall back to reading
> + * the page tables. Since this is called at interrupt level,
> + * do_page_fault() won't treat a DSI as a page fault.
> + */
> +static inline int __read_user_stack(const void __user *ptr, void *ret,
> + size_t size)
> +{
> + int rc;
> +
> + if ((unsigned long)ptr > TASK_SIZE - size ||
> + ((unsigned long)ptr & (size - 1)))
> + return -EFAULT;
> + rc = probe_user_read(ret, ptr, size);
> +
> + if (rc && IS_ENABLED(CONFIG_PPC64))
gcc is probably smart enough to deal with it efficiently, but it would
be more correct to test rc after checking CONFIG_PPC64.
> + return read_user_stack_slow(ptr, ret, size);
> +
> + return rc;
> +}
> +
> #endif /* _POWERPC_PERF_CALLCHAIN_H */
> diff --git a/arch/powerpc/perf/callchain_32.c b/arch/powerpc/perf/callchain_32.c
> index 8aa951003141..1b4621f177e8 100644
> --- a/arch/powerpc/perf/callchain_32.c
> +++ b/arch/powerpc/perf/callchain_32.c
> @@ -31,26 +31,9 @@
>
> #endif /* CONFIG_PPC64 */
>
> -/*
> - * On 32-bit we just access the address and let hash_page create a
> - * HPTE if necessary, so there is no need to fall back to reading
> - * the page tables. Since this is called at interrupt level,
> - * do_page_fault() won't treat a DSI as a page fault.
> - */
> -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> +static int read_user_stack_32(const unsigned int __user *ptr, unsigned int *ret)
> {
> - int rc;
> -
> - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> - ((unsigned long)ptr & 3))
> - return -EFAULT;
> -
> - rc = probe_user_read(ret, ptr, sizeof(*ret));
> -
> - if (IS_ENABLED(CONFIG_PPC64) && rc)
> - return read_user_stack_slow(ptr, ret, 4);
> -
> - return rc;
> + return __read_user_stack(ptr, ret, sizeof(*ret);
> }
>
> /*
> diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c
> index df1ffd8b20f2..55bbc25a54ed 100644
> --- a/arch/powerpc/perf/callchain_64.c
> +++ b/arch/powerpc/perf/callchain_64.c
> @@ -24,7 +24,7 @@
> * interrupt context, so if the access faults, we read the page tables
> * to find which page (if any) is mapped and access it directly.
> */
> -int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> +int read_user_stack_slow(const void __user *ptr, void *buf, int nb)
> {
> int ret = -EFAULT;
> pgd_t *pgdir;
> @@ -65,16 +65,10 @@ int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> return ret;
> }
>
> -static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
> +static int read_user_stack_64(const unsigned long __user *ptr,
> + unsigned long *ret)
> {
> - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
> - ((unsigned long)ptr & 7))
> - return -EFAULT;
> -
> - if (!probe_user_read(ret, ptr, sizeof(*ret)))
> - return 0;
> -
> - return read_user_stack_slow(ptr, ret, 8);
> + return __read_user_stack(ptr, ret, sizeof(*ret));
> }
>
> /*
>
Christophe
^ permalink raw reply
* [PATCH v3 15/15] powerpc: make unrecoverable NMIs die instead of panic
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
System Reset and Machine Check interrupts that are not recoverable due
to being nested or interrupting when RI=0 currently panic. This is
not necessary, and can often just kill the current context and recover.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/traps.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 1beae89bb871..afed3de33a9a 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -513,11 +513,11 @@ void system_reset_exception(struct pt_regs *regs)
#ifdef CONFIG_PPC_BOOK3S_64
BUG_ON(get_paca()->in_nmi == 0);
if (get_paca()->in_nmi > 1)
- nmi_panic(regs, "Unrecoverable nested System Reset");
+ die("Unrecoverable nested System Reset", regs, SIGABRT);
#endif
/* Must die if the interrupt is not recoverable */
if (!(regs->msr & MSR_RI))
- nmi_panic(regs, "Unrecoverable System Reset");
+ die("Unrecoverable System Reset", regs, SIGABRT);
if (saved_hsrrs) {
mtspr(SPRN_HSRR0, hsrr0);
@@ -858,7 +858,7 @@ void machine_check_exception(struct pt_regs *regs)
bail:
/* Must die if the interrupt is not recoverable */
if (!(regs->msr & MSR_RI))
- nmi_panic(regs, "Unrecoverable Machine check");
+ die("Unrecoverable Machine check", regs, SIGBUS);
}
void SMIException(struct pt_regs *regs)
--
2.23.0
^ permalink raw reply related
* [PATCH v3 14/15] powerpc/64s: system reset do not trace
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Naveen N . Rao, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
Similarly to the previous patch, do not trace system reset. This code
is used when there is a crash or hang, and tracing disturbs the system
more and has been known to crash in the crash handling path.
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/traps.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 9f221772eb73..1beae89bb871 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -443,6 +443,9 @@ void system_reset_exception(struct pt_regs *regs)
unsigned long hsrr0, hsrr1;
bool nested = in_nmi();
bool saved_hsrrs = false;
+ u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
+
+ this_cpu_set_ftrace_enabled(0);
/*
* Avoid crashes in case of nested NMI exceptions. Recoverability
@@ -524,6 +527,8 @@ void system_reset_exception(struct pt_regs *regs)
if (!nested)
nmi_exit();
+ this_cpu_set_ftrace_enabled(ftrace_enabled);
+
/* What should we do here? We could issue a shutdown or hard reset. */
}
--
2.23.0
^ permalink raw reply related
* [PATCH v3 13/15] powerpc/64s: machine check do not trace real-mode handler
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Naveen N . Rao, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
Rather than notrace annotations throughout a significant part of the
machine check code across kernel/ pseries/ and powernv/ which can
easily be broken and is infrequently tested, use paca->ftrace_enabled
to blanket-disable tracing of the real-mode non-maskable handler.
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/mce.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index be7e3f92a7b5..fd90c0eda229 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -16,6 +16,7 @@
#include <linux/export.h>
#include <linux/irq_work.h>
#include <linux/extable.h>
+#include <linux/ftrace.h>
#include <asm/machdep.h>
#include <asm/mce.h>
@@ -571,10 +572,14 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
*
* regs->nip and regs->msr contains srr0 and ssr1.
*/
-long machine_check_early(struct pt_regs *regs)
+long notrace machine_check_early(struct pt_regs *regs)
{
long handled = 0;
bool nested = in_nmi();
+ u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
+
+ this_cpu_set_ftrace_enabled(0);
+
if (!nested)
nmi_enter();
@@ -589,6 +594,8 @@ long machine_check_early(struct pt_regs *regs)
if (!nested)
nmi_exit();
+ this_cpu_set_ftrace_enabled(ftrace_enabled);
+
return handled;
}
--
2.23.0
^ permalink raw reply related
* [PATCH v3 12/15] powerpc: ftrace_enabled helper
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Naveen N . Rao, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/ftrace.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index f54a08a2cd70..bc76970b6ee5 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -108,9 +108,23 @@ static inline void this_cpu_enable_ftrace(void)
{
get_paca()->ftrace_enabled = 1;
}
+
+/* Disable ftrace on this CPU if possible (may not be implemented) */
+static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled)
+{
+ get_paca()->ftrace_enabled = ftrace_enabled;
+}
+
+static inline u8 this_cpu_get_ftrace_enabled(void)
+{
+ return get_paca()->ftrace_enabled;
+}
+
#else /* CONFIG_PPC64 */
static inline void this_cpu_disable_ftrace(void) { }
static inline void this_cpu_enable_ftrace(void) { }
+static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled) { }
+static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; }
#endif /* CONFIG_PPC64 */
#endif /* !__ASSEMBLY__ */
--
2.23.0
^ permalink raw reply related
* [PATCH v3 11/15] powerpc/64s: machine check interrupt update NMI accounting
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
machine_check_early is taken as an NMI, so nmi_enter is used there.
machine_check_exception is no longer taken as an NMI (it's invoked
via irq_work in the case a machine check hits in kernel mode), so
remove the nmi_enter from that case.
In NMI context, hash faults don't try to refill the hash table, which
can lead to crashes accessing non-pinned kernel pages. System reset
still has this potential problem.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/mce.c | 7 +++++++
arch/powerpc/kernel/process.c | 2 +-
arch/powerpc/kernel/traps.c | 13 +------------
3 files changed, 9 insertions(+), 13 deletions(-)
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index 8077b5fb18a7..be7e3f92a7b5 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -574,6 +574,9 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
long machine_check_early(struct pt_regs *regs)
{
long handled = 0;
+ bool nested = in_nmi();
+ if (!nested)
+ nmi_enter();
hv_nmi_check_nonrecoverable(regs);
@@ -582,6 +585,10 @@ long machine_check_early(struct pt_regs *regs)
*/
if (ppc_md.machine_check_early)
handled = ppc_md.machine_check_early(regs);
+
+ if (!nested)
+ nmi_exit();
+
return handled;
}
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 9c21288f8645..44410dd3029f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1421,7 +1421,7 @@ void show_regs(struct pt_regs * regs)
pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
#endif
#ifdef CONFIG_PPC64
- pr_cont("IRQMASK: %lx ", regs->softe);
+ pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe, (int)get_paca()->in_nmi, (int)get_paca()->in_mce);
#endif
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
if (MSR_TM_ACTIVE(regs->msr))
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 3fca22276bb1..9f221772eb73 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -823,9 +823,6 @@ int machine_check_generic(struct pt_regs *regs)
void machine_check_exception(struct pt_regs *regs)
{
int recover = 0;
- bool nested = in_nmi();
- if (!nested)
- nmi_enter();
__this_cpu_inc(irq_stat.mce_exceptions);
@@ -851,20 +848,12 @@ void machine_check_exception(struct pt_regs *regs)
if (check_io_access(regs))
goto bail;
- if (!nested)
- nmi_exit();
-
die("Machine check", regs, SIGBUS);
+bail:
/* Must die if the interrupt is not recoverable */
if (!(regs->msr & MSR_RI))
nmi_panic(regs, "Unrecoverable Machine check");
-
- return;
-
-bail:
- if (!nested)
- nmi_exit();
}
void SMIException(struct pt_regs *regs)
--
2.23.0
^ permalink raw reply related
* [PATCH v3 10/15] powerpc/pseries: machine check use rtas_call_unlocked with args on stack
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
With the previous patch, machine checks can use rtas_call_unlocked
which avoids the rtas spinlock which would deadlock if a machine
check hits while making an rtas call.
This also avoids the complex rtas error logging which has more rtas calls
and includes kmalloc (which can return memory beyond RMA, which would
also crash).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/platforms/pseries/ras.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index d65bc38bcb8f..4fd138ae26fd 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -468,7 +468,15 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
*/
static void fwnmi_release_errinfo(void)
{
- int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
+ struct rtas_args rtas_args;
+ int ret;
+
+ /*
+ * On pseries, the machine check stack is limited to under 4GB, so
+ * args can be on-stack.
+ */
+ rtas_call_unlocked(&rtas_args, ibm_nmi_interlock_token, 0, 1, NULL);
+ ret = be32_to_cpu(rtas_args.rets[0]);
if (ret != 0)
printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
}
--
2.23.0
^ permalink raw reply related
* [PATCH v3 09/15] powerpc/pseries: limit machine check stack to 4GB
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar,
Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
This allows rtas_args to be put on the machine check stack, which
avoids a lot of complications with re-entrancy deadlocks.
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/setup_64.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 438a9befce41..defe05b6b7a9 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -709,7 +709,7 @@ void __init exc_lvl_early_init(void)
*/
void __init emergency_stack_init(void)
{
- u64 limit;
+ u64 limit, mce_limit;
unsigned int i;
/*
@@ -726,7 +726,16 @@ void __init emergency_stack_init(void)
* initialized in kernel/irq.c. These are initialized here in order
* to have emergency stacks available as early as possible.
*/
- limit = min(ppc64_bolted_size(), ppc64_rma_size);
+ limit = mce_limit = min(ppc64_bolted_size(), ppc64_rma_size);
+
+ /*
+ * Machine check on pseries calls rtas, but can't use the static
+ * rtas_args due to a machine check hitting while the lock is held.
+ * rtas args have to be under 4GB, so the machine check stack is
+ * limited to 4GB so args can be put on stack.
+ */
+ if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > SZ_4G)
+ mce_limit = SZ_4G;
for_each_possible_cpu(i) {
paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
@@ -736,7 +745,7 @@ void __init emergency_stack_init(void)
paca_ptrs[i]->nmi_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
/* emergency stack for machine check exception handling. */
- paca_ptrs[i]->mc_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
+ paca_ptrs[i]->mc_emergency_sp = alloc_stack(mce_limit, i) + THREAD_SIZE;
#endif
}
}
--
2.23.0
^ permalink raw reply related
* [PATCH v3 08/15] powerpc/pseries/ras: fwnmi sreset should not interlock
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
PAPR does not specify that fwnmi sreset should be interlocked, and
PowerVM (and therefore now QEMU) do not require it.
These "ibm,nmi-interlock" calls are ignored by firmware, but there
is a possibility that the sreset could have interrupted a machine
check and release the machine check's interlock too early, corrupting
it if another machine check came in.
This is an extremely rare case, but it should be fixed for clarity
and reducing the code executed in the sreset path. Firmware also
does not provide error information for the sreset case to look at, so
remove that comment.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/platforms/pseries/ras.c | 46 +++++++++++++++++++---------
1 file changed, 32 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index 2c60e2be1bc5..d65bc38bcb8f 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -406,6 +406,20 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
return (struct rtas_error_log *)local_paca->mce_data_buf;
}
+static unsigned long *fwnmi_get_savep(struct pt_regs *regs)
+{
+ unsigned long savep_ra;
+
+ /* Mask top two bits */
+ savep_ra = regs->gpr[3] & ~(0x3UL << 62);
+ if (!VALID_FWNMI_BUFFER(savep_ra)) {
+ printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
+ return NULL;
+ }
+
+ return __va(savep_ra);
+}
+
/*
* Get the error information for errors coming through the
* FWNMI vectors. The pt_regs' r3 will be updated to reflect
@@ -423,20 +437,14 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
*/
static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
{
- unsigned long savep_ra;
unsigned long *savep;
struct rtas_error_log *h;
- /* Mask top two bits */
- savep_ra = regs->gpr[3] & ~(0x3UL << 62);
-
- if (!VALID_FWNMI_BUFFER(savep_ra)) {
- printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
+ savep = fwnmi_get_savep(regs);
+ if (!savep)
return NULL;
- }
- savep = __va(savep_ra);
- regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
+ regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
h = (struct rtas_error_log *)&savep[1];
/* Use the per cpu buffer from paca to store rtas error log */
@@ -483,11 +491,21 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
#endif
if (fwnmi_active) {
- struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
- if (errhdr) {
- /* XXX Should look at FWNMI information */
- }
- fwnmi_release_errinfo();
+ unsigned long *savep;
+
+ /*
+ * Firmware (PowerVM and KVM) saves r3 to a save area like
+ * machine check, which is not exactly what PAPR (2.9)
+ * suggests but there is no way to detect otherwise, so this
+ * is the interface now.
+ *
+ * System resets do not save any error log or require an
+ * "ibm,nmi-interlock" rtas call to release.
+ */
+
+ savep = fwnmi_get_savep(regs);
+ if (savep)
+ regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
}
if (smp_handle_nmi_ipi(regs))
--
2.23.0
^ permalink raw reply related
* [PATCH v3 07/15] powerpc/pseries/ras: fwnmi avoid modifying r3 in error case
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
If there is some error with the fwnmi save area, r3 has already been
modified which doesn't help with debugging.
Only update r3 when to restore the saved value.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/platforms/pseries/ras.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index ed43c2e4d4ee..2c60e2be1bc5 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -423,18 +423,19 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
*/
static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
{
+ unsigned long savep_ra;
unsigned long *savep;
struct rtas_error_log *h;
/* Mask top two bits */
- regs->gpr[3] &= ~(0x3UL << 62);
+ savep_ra = regs->gpr[3] & ~(0x3UL << 62);
- if (!VALID_FWNMI_BUFFER(regs->gpr[3])) {
+ if (!VALID_FWNMI_BUFFER(savep_ra)) {
printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
return NULL;
}
- savep = __va(regs->gpr[3]);
+ savep = __va(savep_ra);
regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
h = (struct rtas_error_log *)&savep[1];
--
2.23.0
^ permalink raw reply related
* [PATCH v3 06/15] powerpc/pseries/ras: FWNMI_VALID off by one
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar,
Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
This was discovered developing qemu fwnmi sreset support. This
off-by-one bug means the last 16 bytes of the rtas area can not
be used for a 16 byte save area.
It's not a serious bug, and QEMU implementation has to retain a
workaround for old kernels, but it's good to tighten it.
Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/platforms/pseries/ras.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index 972b95ebc867..ed43c2e4d4ee 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -395,10 +395,11 @@ static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
/*
* Some versions of FWNMI place the buffer inside the 4kB page starting at
* 0x7000. Other versions place it inside the rtas buffer. We check both.
+ * Minimum size of the buffer is 16 bytes.
*/
#define VALID_FWNMI_BUFFER(A) \
- ((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
- (((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
+ ((((A) >= 0x7000) && ((A) <= 0x8000 - 16)) || \
+ (((A) >= rtas.base) && ((A) <= (rtas.base + rtas.size - 16))))
static inline struct rtas_error_log *fwnmi_get_errlog(void)
{
--
2.23.0
^ permalink raw reply related
* [PATCH v3 05/15] powerpc/pseries/ras: avoid calling rtas_token in NMI paths
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar,
Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
In the interest of reducing code and possible failures in the
machine check and system reset paths, grab the "ibm,nmi-interlock"
token at init time.
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/include/asm/firmware.h | 1 +
arch/powerpc/platforms/pseries/ras.c | 2 +-
arch/powerpc/platforms/pseries/setup.c | 14 ++++++++++----
3 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/firmware.h b/arch/powerpc/include/asm/firmware.h
index ca33f4ef6cb4..6003c2e533a0 100644
--- a/arch/powerpc/include/asm/firmware.h
+++ b/arch/powerpc/include/asm/firmware.h
@@ -128,6 +128,7 @@ extern void machine_check_fwnmi(void);
/* This is true if we are using the firmware NMI handler (typically LPAR) */
extern int fwnmi_active;
+extern int ibm_nmi_interlock_token;
extern unsigned int __start___fw_ftr_fixup, __stop___fw_ftr_fixup;
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index aa6208c8d4f0..972b95ebc867 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -458,7 +458,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
*/
static void fwnmi_release_errinfo(void)
{
- int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
+ int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
if (ret != 0)
printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
}
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 0c8421dd01ab..dd234095ae4f 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -83,6 +83,7 @@ unsigned long CMO_PageSize = (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K);
EXPORT_SYMBOL(CMO_PageSize);
int fwnmi_active; /* TRUE if an FWNMI handler is present */
+int ibm_nmi_interlock_token;
static void pSeries_show_cpuinfo(struct seq_file *m)
{
@@ -113,9 +114,14 @@ static void __init fwnmi_init(void)
struct slb_entry *slb_ptr;
size_t size;
#endif
+ int ibm_nmi_register_token;
- int ibm_nmi_register = rtas_token("ibm,nmi-register");
- if (ibm_nmi_register == RTAS_UNKNOWN_SERVICE)
+ ibm_nmi_register_token = rtas_token("ibm,nmi-register");
+ if (ibm_nmi_register_token == RTAS_UNKNOWN_SERVICE)
+ return;
+
+ ibm_nmi_interlock_token = rtas_token("ibm,nmi-interlock");
+ if (WARN_ON(ibm_nmi_interlock_token == RTAS_UNKNOWN_SERVICE))
return;
/* If the kernel's not linked at zero we point the firmware at low
@@ -123,8 +129,8 @@ static void __init fwnmi_init(void)
system_reset_addr = __pa(system_reset_fwnmi) - PHYSICAL_START;
machine_check_addr = __pa(machine_check_fwnmi) - PHYSICAL_START;
- if (0 == rtas_call(ibm_nmi_register, 2, 1, NULL, system_reset_addr,
- machine_check_addr))
+ if (0 == rtas_call(ibm_nmi_register_token, 2, 1, NULL,
+ system_reset_addr, machine_check_addr))
fwnmi_active = 1;
/*
--
2.23.0
^ permalink raw reply related
* [PATCH v3 04/15] powerpc/64s/exceptions: machine check reconcile irq state
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
pseries fwnmi machine check code pops the soft-irq checks in rtas_call
(after the previous patch to remove rtas_token from this call path).
Rather than play whack a mole with these and forever having fragile
code, it seems better to have the early machine check handler perform
the same kind of reconcile as the other NMI interrupts.
WARNING: CPU: 0 PID: 493 at arch/powerpc/kernel/irq.c:343
CPU: 0 PID: 493 Comm: a Tainted: G W
NIP: c00000000001ed2c LR: c000000000042c40 CTR: 0000000000000000
REGS: c0000001fffd38b0 TRAP: 0700 Tainted: G W
MSR: 8000000000021003 <SF,ME,RI,LE> CR: 28000488 XER: 00000000
CFAR: c00000000001ec90 IRQMASK: 0
GPR00: c000000000043820 c0000001fffd3b40 c0000000012ba300 0000000000000000
GPR04: 0000000048000488 0000000000000000 0000000000000000 00000000deadbeef
GPR08: 0000000000000080 0000000000000000 0000000000000000 0000000000001001
GPR12: 0000000000000000 c0000000014a0000 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR28: 0000000000000000 0000000000000001 c000000001360810 0000000000000000
NIP [c00000000001ed2c] arch_local_irq_restore.part.0+0xac/0x100
LR [c000000000042c40] unlock_rtas+0x30/0x90
Call Trace:
[c0000001fffd3b40] [c000000001360810] 0xc000000001360810 (unreliable)
[c0000001fffd3b60] [c000000000043820] rtas_call+0x1c0/0x280
[c0000001fffd3bb0] [c0000000000dc328] fwnmi_release_errinfo+0x38/0x70
[c0000001fffd3c10] [c0000000000dcd8c] pseries_machine_check_realmode+0x1dc/0x540
[c0000001fffd3cd0] [c00000000003fe04] machine_check_early+0x54/0x70
[c0000001fffd3d00] [c000000000008384] machine_check_early_common+0x134/0x1f0
--- interrupt: 200 at 0x13f1307c8
LR = 0x7fff888b8528
Instruction dump:
60000000 7d2000a6 71298000 41820068 39200002 7d210164 4bffff9c 60000000
60000000 7d2000a6 71298000 4c820020 <0fe00000> 4e800020 60000000 60000000
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index a42b73efb1a9..072772803b7c 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1116,11 +1116,30 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
li r10,MSR_RI
mtmsrd r10,1
+ /*
+ * Set IRQS_ALL_DISABLED and save PACAIRQHAPPENED (see
+ * system_reset_common)
+ */
+ li r10,IRQS_ALL_DISABLED
+ stb r10,PACAIRQSOFTMASK(r13)
+ lbz r10,PACAIRQHAPPENED(r13)
+ std r10,RESULT(r1)
+ ori r10,r10,PACA_IRQ_HARD_DIS
+ stb r10,PACAIRQHAPPENED(r13)
+
addi r3,r1,STACK_FRAME_OVERHEAD
bl machine_check_early
std r3,RESULT(r1) /* Save result */
ld r12,_MSR(r1)
+ /*
+ * Restore soft mask settings.
+ */
+ ld r10,RESULT(r1)
+ stb r10,PACAIRQHAPPENED(r13)
+ ld r10,SOFTE(r1)
+ stb r10,PACAIRQSOFTMASK(r13)
+
#ifdef CONFIG_PPC_P7_NAP
/*
* Check if thread was in power saving mode. We come here when any
--
2.23.0
^ permalink raw reply related
* [PATCH v3 03/15] powerpc/64s/exceptions: Change irq reconcile for NMIs from reusing _DAR to RESULT
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
A spare interrupt stack slot is needed to save irq state when
reconciling NMIs (sreset and decrementer soft-nmi). _DAR is used
for this, but we want to reconcile machine checks as well, which
do use _DAR. Switch to using RESULT instead, as it's used by
system calls.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 3322000316ab..a42b73efb1a9 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -939,13 +939,13 @@ EXC_COMMON_BEGIN(system_reset_common)
* the right thing. We do not want to reconcile because that goes
* through irq tracing which we don't want in NMI.
*
- * Save PACAIRQHAPPENED to _DAR (otherwise unused), and set HARD_DIS
+ * Save PACAIRQHAPPENED to RESULT (otherwise unused), and set HARD_DIS
* as we are running with MSR[EE]=0.
*/
li r10,IRQS_ALL_DISABLED
stb r10,PACAIRQSOFTMASK(r13)
lbz r10,PACAIRQHAPPENED(r13)
- std r10,_DAR(r1)
+ std r10,RESULT(r1)
ori r10,r10,PACA_IRQ_HARD_DIS
stb r10,PACAIRQHAPPENED(r13)
@@ -966,7 +966,7 @@ EXC_COMMON_BEGIN(system_reset_common)
/*
* Restore soft mask settings.
*/
- ld r10,_DAR(r1)
+ ld r10,RESULT(r1)
stb r10,PACAIRQHAPPENED(r13)
ld r10,SOFTE(r1)
stb r10,PACAIRQSOFTMASK(r13)
@@ -2743,7 +2743,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
li r10,IRQS_ALL_DISABLED
stb r10,PACAIRQSOFTMASK(r13)
lbz r10,PACAIRQHAPPENED(r13)
- std r10,_DAR(r1)
+ std r10,RESULT(r1)
ori r10,r10,PACA_IRQ_HARD_DIS
stb r10,PACAIRQHAPPENED(r13)
@@ -2757,7 +2757,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
/*
* Restore soft mask settings.
*/
- ld r10,_DAR(r1)
+ ld r10,RESULT(r1)
stb r10,PACAIRQHAPPENED(r13)
ld r10,SOFTE(r1)
stb r10,PACAIRQSOFTMASK(r13)
--
2.23.0
^ permalink raw reply related
* [PATCH v3 02/15] powerpc/64s/exceptions: Fix in_mce accounting in unrecoverable path
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar,
Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index bbf3109c5cba..3322000316ab 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1267,6 +1267,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
andc r10,r10,r3
mtmsrd r10
+ lhz r12,PACA_IN_MCE(r13)
+ subi r12,r12,1
+ sth r12,PACA_IN_MCE(r13)
+
/* Invoke machine_check_exception to print MCE event and panic. */
addi r3,r1,STACK_FRAME_OVERHEAD
bl machine_check_exception
--
2.23.0
^ permalink raw reply related
* [PATCH v3 01/15] powerpc/64s/exception: Fix machine check no-loss idle wakeup
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
In-Reply-To: <20200407051636.648369-1-npiggin@gmail.com>
The architecture allows for machine check exceptions to cause idle
wakeups which resume at the 0x200 address which has to return via
the idle wakeup code, but the early machine check handler is run
first.
The case of a no state-loss sleep is broken because the early
handler uses non-volatile register r1 , which is needed for the wakeup
protocol, but it is not restored.
Fix this by loading r1 from the MCE exception frame before returning
to the idle wakeup code. Also update the comment which has become
stale since the idle rewrite in C.
Fixes: 10d91611f426d ("powerpc/64s: Reimplement book3s idle code in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 728ccb0f560c..bbf3109c5cba 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1224,17 +1224,19 @@ EXC_COMMON_BEGIN(machine_check_idle_common)
bl machine_check_queue_event
/*
- * We have not used any non-volatile GPRs here, and as a rule
- * most exception code including machine check does not.
- * Therefore PACA_NAPSTATELOST does not need to be set. Idle
- * wakeup will restore volatile registers.
+ * GPR-loss wakeups are relatively straightforward, because the
+ * idle sleep code has saved all non-volatile registers on its
+ * own stack, and r1 in PACAR1.
*
- * Load the original SRR1 into r3 for pnv_powersave_wakeup_mce.
+ * For no-loss wakeups the r1 and lr registers used by the
+ * early machine check handler have to be restored first. r2 is
+ * the kernel TOC, so no need to restore it.
*
* Then decrement MCE nesting after finishing with the stack.
*/
ld r3,_MSR(r1)
ld r4,_LINK(r1)
+ ld r1,GPR1(r1)
lhz r11,PACA_IN_MCE(r13)
subi r11,r11,1
@@ -1243,7 +1245,7 @@ EXC_COMMON_BEGIN(machine_check_idle_common)
mtlr r4
rlwinm r10,r3,47-31,30,31
cmpwi cr1,r10,2
- bltlr cr1 /* no state loss, return to idle caller */
+ bltlr cr1 /* no state loss, return to idle caller with r3=SRR1 */
b idle_return_gpr_loss
#endif
--
2.23.0
^ permalink raw reply related
* [PATCH v3 00/15] powerpc/64: machine check and system reset fixes
From: Nicholas Piggin @ 2020-04-07 5:16 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Mahesh Salgaonkar, Ganesh Goudar, Nicholas Piggin
There's a bunch of problems we hit bringing up fwnmi sreset and testing
with mce injection on QEMU. Mostly pseries issues.
This series of fixes applies on top of next-test, the machine
check reconcile patch won't apply cleanly to previous kernels but
it might want to be backported. We can do that after upstreaming.
This doesn't solve all known problems yet, but fwnmi machine check
and system reset injection in QEMU is significantly better. There
will be more to come but these should be ready for review now.
Thanks,
Nick
v3:
- Addressed comments and fixed compile bugs.
- Didn't convert to pr_err because it's an existing printk that was
moved. A cleanup to convert printks could go afterward.
v2:
- Added a couple more fixes
- Review comments and tags
- Re-tested with some fixes to my qemu machine check injection patches
Nicholas Piggin (15):
powerpc/64s/exception: Fix machine check no-loss idle wakeup
powerpc/64s/exceptions: Fix in_mce accounting in unrecoverable path
powerpc/64s/exceptions: Change irq reconcile for NMIs from reusing
_DAR to RESULT
powerpc/64s/exceptions: machine check reconcile irq state
powerpc/pseries/ras: avoid calling rtas_token in NMI paths
powerpc/pseries/ras: FWNMI_VALID off by one
powerpc/pseries/ras: fwnmi avoid modifying r3 in error case
powerpc/pseries/ras: fwnmi sreset should not interlock
powerpc/pseries: limit machine check stack to 4GB
powerpc/pseries: machine check use rtas_call_unlocked with args on
stack
powerpc/64s: machine check interrupt update NMI accounting
powerpc: ftrace_enabled helper
powerpc/64s: machine check do not trace real-mode handler
powerpc/64s: system reset do not trace
powerpc: make unrecoverable NMIs die instead of panic
arch/powerpc/include/asm/firmware.h | 1 +
arch/powerpc/include/asm/ftrace.h | 14 ++++++
arch/powerpc/kernel/exceptions-64s.S | 47 +++++++++++++++-----
arch/powerpc/kernel/mce.c | 16 ++++++-
arch/powerpc/kernel/process.c | 2 +-
arch/powerpc/kernel/setup_64.c | 15 +++++--
arch/powerpc/kernel/traps.c | 24 ++++-------
arch/powerpc/platforms/pseries/ras.c | 60 +++++++++++++++++++-------
arch/powerpc/platforms/pseries/setup.c | 14 ++++--
9 files changed, 142 insertions(+), 51 deletions(-)
--
2.23.0
^ permalink raw reply
* Re: [PATCH v2 05/14] powerpc/pseries/ras: avoid calling rtas_token in NMI paths
From: Nicholas Piggin @ 2020-04-07 4:35 UTC (permalink / raw)
To: Christophe Leroy, linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar
In-Reply-To: <26bde8af-b499-78f1-2f9a-91972ab343c6@c-s.fr>
Christophe Leroy's on April 4, 2020 12:30 am:
>
>
> Le 03/04/2020 à 15:26, Nicholas Piggin a écrit :
>> In the interest of reducing code and possible failures in the
>> machine check and system reset paths, grab the "ibm,nmi-interlock"
>> token at init time.
>>
>> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>> arch/powerpc/include/asm/firmware.h | 1 +
>> arch/powerpc/platforms/pseries/ras.c | 2 +-
>> arch/powerpc/platforms/pseries/setup.c | 13 ++++++++++---
>> 3 files changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/firmware.h b/arch/powerpc/include/asm/firmware.h
>> index ca33f4ef6cb4..6003c2e533a0 100644
>> --- a/arch/powerpc/include/asm/firmware.h
>> +++ b/arch/powerpc/include/asm/firmware.h
>> @@ -128,6 +128,7 @@ extern void machine_check_fwnmi(void);
>>
>> /* This is true if we are using the firmware NMI handler (typically LPAR) */
>> extern int fwnmi_active;
>> +extern int ibm_nmi_interlock_token;
>>
>> extern unsigned int __start___fw_ftr_fixup, __stop___fw_ftr_fixup;
>>
>> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
>> index 1d7f973c647b..c74d5e740922 100644
>> --- a/arch/powerpc/platforms/pseries/ras.c
>> +++ b/arch/powerpc/platforms/pseries/ras.c
>> @@ -458,7 +458,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
>> */
>> static void fwnmi_release_errinfo(void)
>> {
>> - int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
>> + int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
>> if (ret != 0)
>> printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
>> }
>> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
>> index 0c8421dd01ab..b582198be284 100644
>> --- a/arch/powerpc/platforms/pseries/setup.c
>> +++ b/arch/powerpc/platforms/pseries/setup.c
>> @@ -83,6 +83,7 @@ unsigned long CMO_PageSize = (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K);
>> EXPORT_SYMBOL(CMO_PageSize);
>>
>> int fwnmi_active; /* TRUE if an FWNMI handler is present */
>> +int ibm_nmi_interlock_token;
>>
>> static void pSeries_show_cpuinfo(struct seq_file *m)
>> {
>> @@ -113,9 +114,14 @@ static void __init fwnmi_init(void)
>> struct slb_entry *slb_ptr;
>> size_t size;
>> #endif
>> + int ibm_nmi_register_token;
>>
>> - int ibm_nmi_register = rtas_token("ibm,nmi-register");
>> - if (ibm_nmi_register == RTAS_UNKNOWN_SERVICE)
>> + ibm_nmi_register_token = rtas_token("ibm,nmi-register");
>> + if (ibm_nmi_register_token == RTAS_UNKNOWN_SERVICE)
>> + return;
>> +
>> + ibm_nmi_interlock_token = rtas_token("ibm,nmi-interlock");
>> + if (WARN_ON(ibm_nmi_interlock_token == RTAS_UNKNOWN_SERVICE))
>> return;
>>
>> /* If the kernel's not linked at zero we point the firmware at low
>> @@ -123,7 +129,8 @@ static void __init fwnmi_init(void)
>> system_reset_addr = __pa(system_reset_fwnmi) - PHYSICAL_START;
>> machine_check_addr = __pa(machine_check_fwnmi) - PHYSICAL_START;
>>
>> - if (0 == rtas_call(ibm_nmi_register, 2, 1, NULL, system_reset_addr,
>> + if (0 == rtas_call(ibm_nmi_register_token, 2, 1, NULL,
>> + system_reset_addr,
>> machine_check_addr))
>
> Alignment is wrong.
> And you could put system_reset_addr and
> machine_check_addr on the same line to limit the number of lines of the if.
I don't really like using spaces to align but I'll put it on the same
line.
Thanks,
Nick
^ permalink raw reply
* Re: [PATCH v2 09/14] powerpc/pseries: limit machine check stack to 4GB
From: Nicholas Piggin @ 2020-04-07 4:31 UTC (permalink / raw)
To: Christophe Leroy, linuxppc-dev
Cc: Mahesh Salgaonkar, Ganesh Goudar, Mahesh Salgaonkar
In-Reply-To: <2b114363-7fa9-8383-0b95-93540e00f2a8@c-s.fr>
Christophe Leroy's on April 4, 2020 12:19 am:
>
>
> Le 03/04/2020 à 15:26, Nicholas Piggin a écrit :
>> This allows rtas_args to be put on the machine check stack, which
>> avoids a lot of complications with re-entrancy deadlocks.
>>
>> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>> arch/powerpc/kernel/setup_64.c | 17 ++++++++++++++++-
>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
>> index e05e6dd67ae6..3a2428aa3d9a 100644
>> --- a/arch/powerpc/kernel/setup_64.c
>> +++ b/arch/powerpc/kernel/setup_64.c
>> @@ -692,6 +692,9 @@ void __init exc_lvl_early_init(void)
>> void __init emergency_stack_init(void)
>> {
>> u64 limit;
>> +#ifdef CONFIG_PPC_BOOK3S_64
>
> #ifdef not needed, see below
>
>> + u64 mce_limit;
>> +#endif
>> unsigned int i;
>>
>> /*
>> @@ -710,6 +713,18 @@ void __init emergency_stack_init(void)
>> */
>> limit = min(ppc64_bolted_size(), ppc64_rma_size);
>>
>> + /*
>> + * Machine check on pseries calls rtas, but can't use the static
>> + * rtas_args due to a machine check hitting while the lock is held.
>> + * rtas args have to be under 4GB, so the machine check stack is
>> + * limited to 4GB so args can be put on stack.
>> + */
>> +#ifdef CONFIG_PPC_BOOK3S_64
>
> This ifdef is not needed. FW_FEATURE_LPAR is only possible on
> CONFIG_PPC_BOOK3S_64 (indeed only on PSERIES or PS3). On others
> firmware_has_feature(FW_FEATURE_LPAR) should return 0 at compile time.
Sure I'll remove it.
>> + mce_limit = limit;
>> + if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > 4UL*1024*1024*1024)
>> + mce_limit = 4UL*1024*1024*1024;
>
> You should use SZ_4G instead of hardcoding.
Will do.
Thanks,
Nick
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