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Merge branch 'for-next/errata' into for-next/core

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Rework of the workaround for Cortex-A76 erratum 1463225 to fit in better
with the ongoing exception entry cleanups and changes to the detection
code for Cortex-A55 erratum 1024718 since it applies to all revisions of
the silicon.

* for-next/errata:
  arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround
  arm64: Extend workaround for erratum 1024718 to all versions of Cortex-A55
This commit is contained in:
Will Deacon 2021-02-12 14:57:13 +00:00
commit 90eb8c9d94
6 changed files with 55 additions and 67 deletions
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2
arch/arm64/Kconfig
View File

@ -522,7 +522,7 @@ config ARM64_ERRATUM_1024718
help
This option adds a workaround for ARM Cortex-A55 Erratum 1024718.
Affected Cortex-A55 cores (r0p0, r0p1, r1p0) could cause incorrect
Affected Cortex-A55 cores (all revisions) could cause incorrect
update of the hardware dirty bit when the DBM/AP bits are updated
without a break-before-make. The workaround is to disable the usage
of hardware DBM locally on the affected cores. CPUs not affected by

2
arch/arm64/kernel/cpu_errata.c
View File

@ -107,8 +107,6 @@ cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *cap)
}
#ifdef CONFIG_ARM64_ERRATUM_1463225
DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
static bool
has_cortex_a76_erratum_1463225(const struct arm64_cpu_capabilities *entry,
int scope)

2
arch/arm64/kernel/cpufeature.c
View File

@ -1506,7 +1506,7 @@ static bool cpu_has_broken_dbm(void)
/* List of CPUs which have broken DBM support. */
static const struct midr_range cpus[] = {
#ifdef CONFIG_ARM64_ERRATUM_1024718
MIDR_RANGE(MIDR_CORTEX_A55, 0, 0, 1, 0), // A55 r0p0 -r1p0
MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),
/* Kryo4xx Silver (rdpe => r1p0) */
MIDR_REV(MIDR_QCOM_KRYO_4XX_SILVER, 0xd, 0xe),
#endif

54
arch/arm64/kernel/entry-common.c
View File

@ -109,6 +109,55 @@ asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
exit_to_kernel_mode(regs);
}
#ifdef CONFIG_ARM64_ERRATUM_1463225
static DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
static void cortex_a76_erratum_1463225_svc_handler(void)
{
u32 reg, val;
if (!unlikely(test_thread_flag(TIF_SINGLESTEP)))
return;
if (!unlikely(this_cpu_has_cap(ARM64_WORKAROUND_1463225)))
return;
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 1);
reg = read_sysreg(mdscr_el1);
val = reg | DBG_MDSCR_SS | DBG_MDSCR_KDE;
write_sysreg(val, mdscr_el1);
asm volatile("msr daifclr, #8");
isb();
/* We will have taken a single-step exception by this point */
write_sysreg(reg, mdscr_el1);
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 0);
}
static bool cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
if (!__this_cpu_read(__in_cortex_a76_erratum_1463225_wa))
return false;
/*
* We've taken a dummy step exception from the kernel to ensure
* that interrupts are re-enabled on the syscall path. Return back
* to cortex_a76_erratum_1463225_svc_handler() with debug exceptions
* masked so that we can safely restore the mdscr and get on with
* handling the syscall.
*/
regs->pstate |= PSR_D_BIT;
return true;
}
#else /* CONFIG_ARM64_ERRATUM_1463225 */
static void cortex_a76_erratum_1463225_svc_handler(void) { }
static bool cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
return false;
}
#endif /* CONFIG_ARM64_ERRATUM_1463225 */
static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
@ -186,7 +235,8 @@ static void noinstr el1_dbg(struct pt_regs *regs, unsigned long esr)
gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET);
arm64_enter_el1_dbg(regs);
do_debug_exception(far, esr, regs);
if (!cortex_a76_erratum_1463225_debug_handler(regs))
do_debug_exception(far, esr, regs);
arm64_exit_el1_dbg(regs);
}
@ -362,6 +412,7 @@ static void noinstr el0_svc(struct pt_regs *regs)
gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET);
enter_from_user_mode();
cortex_a76_erratum_1463225_svc_handler();
do_el0_svc(regs);
}
@ -439,6 +490,7 @@ static void noinstr el0_svc_compat(struct pt_regs *regs)
gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET);
enter_from_user_mode();
cortex_a76_erratum_1463225_svc_handler();
do_el0_svc_compat(regs);
}

30
arch/arm64/kernel/syscall.c
View File

@ -65,35 +65,6 @@ static inline bool has_syscall_work(unsigned long flags)
int syscall_trace_enter(struct pt_regs *regs);
void syscall_trace_exit(struct pt_regs *regs);
#ifdef CONFIG_ARM64_ERRATUM_1463225
DECLARE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
static void cortex_a76_erratum_1463225_svc_handler(void)
{
u32 reg, val;
if (!unlikely(test_thread_flag(TIF_SINGLESTEP)))
return;
if (!unlikely(this_cpu_has_cap(ARM64_WORKAROUND_1463225)))
return;
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 1);
reg = read_sysreg(mdscr_el1);
val = reg | DBG_MDSCR_SS | DBG_MDSCR_KDE;
write_sysreg(val, mdscr_el1);
asm volatile("msr daifclr, #8");
isb();
/* We will have taken a single-step exception by this point */
write_sysreg(reg, mdscr_el1);
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 0);
}
#else
static void cortex_a76_erratum_1463225_svc_handler(void) { }
#endif /* CONFIG_ARM64_ERRATUM_1463225 */
static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
const syscall_fn_t syscall_table[])
{
@ -120,7 +91,6 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
* (Similarly for HVC and SMC elsewhere.)
*/
cortex_a76_erratum_1463225_svc_handler();
local_daif_restore(DAIF_PROCCTX);
if (flags & _TIF_MTE_ASYNC_FAULT) {

32
arch/arm64/mm/fault.c
View File

@ -874,44 +874,12 @@ static void debug_exception_exit(struct pt_regs *regs)
}
NOKPROBE_SYMBOL(debug_exception_exit);
#ifdef CONFIG_ARM64_ERRATUM_1463225
DECLARE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
static int cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
if (user_mode(regs))
return 0;
if (!__this_cpu_read(__in_cortex_a76_erratum_1463225_wa))
return 0;
/*
* We've taken a dummy step exception from the kernel to ensure
* that interrupts are re-enabled on the syscall path. Return back
* to cortex_a76_erratum_1463225_svc_handler() with debug exceptions
* masked so that we can safely restore the mdscr and get on with
* handling the syscall.
*/
regs->pstate |= PSR_D_BIT;
return 1;
}
#else
static int cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
return 0;
}
#endif /* CONFIG_ARM64_ERRATUM_1463225 */
NOKPROBE_SYMBOL(cortex_a76_erratum_1463225_debug_handler);
void do_debug_exception(unsigned long addr_if_watchpoint, unsigned int esr,
struct pt_regs *regs)
{
const struct fault_info *inf = esr_to_debug_fault_info(esr);
unsigned long pc = instruction_pointer(regs);
if (cortex_a76_erratum_1463225_debug_handler(regs))
return;
debug_exception_enter(regs);
if (user_mode(regs) && !is_ttbr0_addr(pc))