This patch modifies kernel_neon_begin() and kernel_neon_end(), so they may be called from any context. To address the case where only a couple of registers are needed, kernel_neon_begin_partial(u32) is introduced which takes as a parameter the number of bottom 'n' NEON q-registers required. To mark the end of such a partial section, the regular kernel_neon_end() should be used.
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> --- arch/arm64/include/asm/fpsimd.h | 17 ++++++++++++++ arch/arm64/include/asm/fpsimdmacros.h | 37 ++++++++++++++++++++++++++++++ arch/arm64/include/asm/neon.h | 6 ++++- arch/arm64/kernel/entry-fpsimd.S | 24 +++++++++++++++++++ arch/arm64/kernel/fpsimd.c | 43 +++++++++++++++++++++++------------ 5 files changed, 111 insertions(+), 16 deletions(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index 609bc44ceb8d..dc9ef741c648 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -41,6 +41,19 @@ struct fpsimd_state { unsigned int last_cpu; }; +/* + * Struct for stacking the bottom 'n' FP/SIMD registers. + * Mainly intended for kernel use of v8 Crypto Extensions which only + * needs a few registers and may need to execute in atomic context. + */ +struct fpsimd_partial_state { + u32 num_regs; + u32 fpsr; + u32 fpcr; + __uint128_t vregs[32] __aligned(16); +} __aligned(16); + + #if defined(__KERNEL__) && defined(CONFIG_COMPAT) /* Masks for extracting the FPSR and FPCR from the FPSCR */ #define VFP_FPSCR_STAT_MASK 0xf800009f @@ -57,6 +70,10 @@ struct task_struct; extern void fpsimd_save_state(struct fpsimd_state *state); extern void fpsimd_load_state(struct fpsimd_state *state); +extern void fpsimd_save_partial_state(struct fpsimd_partial_state *state, + u32 num_regs); +extern void fpsimd_load_partial_state(struct fpsimd_partial_state *state); + extern void fpsimd_thread_switch(struct task_struct *next); extern void fpsimd_flush_thread(void); extern void fpsimd_reload_fpstate(void); diff --git a/arch/arm64/include/asm/fpsimdmacros.h b/arch/arm64/include/asm/fpsimdmacros.h index bbec599c96bd..42990a82c671 100644 --- a/arch/arm64/include/asm/fpsimdmacros.h +++ b/arch/arm64/include/asm/fpsimdmacros.h @@ -62,3 +62,40 @@ ldr w\tmpnr, [\state, #16 * 2 + 4] msr fpcr, x\tmpnr .endm + +.altmacro +.macro q2op, op, q1, q2, state + \op q\q1, q\q2, [\state, # -16 * \q1 - 16] +.endm + +.macro fpsimd_save_partial state, numnr, tmpnr1, tmpnr2 + mrs x\tmpnr1, fpsr + str w\numnr, [\state] + mrs x\tmpnr2, fpcr + stp w\tmpnr1, w\tmpnr2, [\state, #4] + adr x\tmpnr1, 0f + add \state, \state, x\numnr, lsl #4 + sub x\tmpnr1, x\tmpnr1, x\numnr, lsl #1 + br x\tmpnr1 + .irp qa, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0 + qb = \qa + 1 + q2op stp, \qa, %qb, \state + .endr +0: +.endm + +.macro fpsimd_restore_partial state, tmpnr1, tmpnr2 + ldp w\tmpnr1, w\tmpnr2, [\state, #4] + msr fpsr, x\tmpnr1 + msr fpcr, x\tmpnr2 + adr x\tmpnr1, 0f + ldr w\tmpnr2, [\state] + add \state, \state, x\tmpnr2, lsl #4 + sub x\tmpnr1, x\tmpnr1, x\tmpnr2, lsl #1 + br x\tmpnr1 + .irp qa, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0 + qb = \qa + 1 + q2op ldp, \qa, %qb, \state + .endr +0: +.endm diff --git a/arch/arm64/include/asm/neon.h b/arch/arm64/include/asm/neon.h index b0cc58a97780..21a9e35655b7 100644 --- a/arch/arm64/include/asm/neon.h +++ b/arch/arm64/include/asm/neon.h @@ -8,7 +8,11 @@ * published by the Free Software Foundation. */ +#include <linux/types.h> + #define cpu_has_neon() (1) -void kernel_neon_begin(void); +#define kernel_neon_begin() kernel_neon_begin_partial(32) + +void kernel_neon_begin_partial(u32 num_regs); void kernel_neon_end(void); diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S index 6a27cd6dbfa6..d358ccacfc00 100644 --- a/arch/arm64/kernel/entry-fpsimd.S +++ b/arch/arm64/kernel/entry-fpsimd.S @@ -41,3 +41,27 @@ ENTRY(fpsimd_load_state) fpsimd_restore x0, 8 ret ENDPROC(fpsimd_load_state) + +#ifdef CONFIG_KERNEL_MODE_NEON + +/* + * Save the bottom n FP registers. + * + * x0 - pointer to struct fpsimd_partial_state + */ +ENTRY(fpsimd_save_partial_state) + fpsimd_save_partial x0, 1, 8, 9 + ret +ENDPROC(fpsimd_load_partial_state) + +/* + * Load the bottom n FP registers. + * + * x0 - pointer to struct fpsimd_partial_state + */ +ENTRY(fpsimd_load_partial_state) + fpsimd_restore_partial x0, 8, 9 + ret +ENDPROC(fpsimd_load_partial_state) + +#endif diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 5b13c17e799f..ac105da56c8c 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -143,30 +143,43 @@ void fpsimd_reload_fpstate(void) #ifdef CONFIG_KERNEL_MODE_NEON +static DEFINE_PER_CPU(struct fpsimd_partial_state, hardirq_fpsimdstate); +static DEFINE_PER_CPU(struct fpsimd_partial_state, softirq_fpsimdstate); + /* * Kernel-side NEON support functions */ -void kernel_neon_begin(void) +void kernel_neon_begin_partial(u32 num_regs) { - /* Avoid using the NEON in interrupt context */ - BUG_ON(in_interrupt()); - preempt_disable(); - - /* - * Save the userland FPSIMD state if we have one and if we haven't done - * so already. Clear fpsimd_last_cpu to indicate that there is no - * longer userland context in the registers. - */ - if (current->mm && !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE)) - fpsimd_save_state(¤t->thread.fpsimd_state); - __get_cpu_var(fpsimd_last_cpu) = NULL; + if (in_interrupt()) { + struct fpsimd_partial_state *s = this_cpu_ptr( + in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate); + BUG_ON(num_regs > 32); + fpsimd_save_partial_state(s, roundup(num_regs, 2)); + } else { + /* + * Save the userland FPSIMD state if we have one and if we + * haven't done so already. Clear fpsimd_last_cpu to indicate + * that there is no longer userland context in the registers. + */ + preempt_disable(); + if (current->mm && + !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE)) + fpsimd_save_state(¤t->thread.fpsimd_state); + __get_cpu_var(fpsimd_last_cpu) = NULL; + } } -EXPORT_SYMBOL(kernel_neon_begin); +EXPORT_SYMBOL(kernel_neon_begin_partial); void kernel_neon_end(void) { - preempt_enable(); + if (in_interrupt()) { + struct fpsimd_partial_state *s = this_cpu_ptr( + in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate); + fpsimd_load_partial_state(s); + } else + preempt_enable(); } EXPORT_SYMBOL(kernel_neon_end); -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/