[RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions

On 11/23, Stephen Boyd wrote:

quoted

On 11/23, Arnd Bergmann wrote:

quoted

Ok, thanks for the confirmation.

Summarizing what we've found, I think we can get away with just
introducing two Kconfig symbols ARCH_MULTI_V7VE and CPU_V7VE.
Most CPUs fall clearly into one category or the other, and then
we can allow LPAE to be selected for V7VE-only build but not
for plain V7, and we can unconditionally build the kernel with

arch-$(CONFIG_CPU_32v7VE)  = -D__LINUX_ARM_ARCH__=7 $(call cc-option,-march=armv7ve,-march=armv7-a -mcpu=cortex-a15)

This causes compiler spew for me:

  warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch

Removing -march=armv7-a from there makes it quiet.

Also, it's sort of feels wrong to have -mcpu in a place where
we're exclusively doing -march. Perhaps the fallback should be
bog standard -march=armv7-a? (or the fallback for that one
"-march=armv5t -Wa$(comma)-march=armv7-a")?

And adding CPU_V7VE causes a cascade of changes to wherever
CPU_V7 is being used today. Here's the patch I currently have,
without the platform changes:

---8<----
 arch/arm/Kconfig                   | 68 +++++++++++++++++++++-----------------
 arch/arm/Kconfig-nommu             |  2 +-
 arch/arm/Makefile                  |  1 +
 arch/arm/boot/compressed/head.S    |  2 +-
 arch/arm/boot/compressed/misc.c    |  2 +-
 arch/arm/include/asm/cacheflush.h  |  2 +-
 arch/arm/include/asm/glue-cache.h  |  2 +-
 arch/arm/include/asm/glue-proc.h   |  2 +-
 arch/arm/include/asm/switch_to.h   |  2 +-
 arch/arm/include/debug/icedcc.S    |  2 +-
 arch/arm/kernel/entry-armv.S       |  6 ++--
 arch/arm/kernel/perf_event_v7.c    |  4 +--
 arch/arm/kvm/Kconfig               |  2 +-
 arch/arm/mm/Kconfig                | 41 ++++++++++++++++-------
 arch/arm/mm/Makefile               |  1 +
 arch/arm/probes/kprobes/test-arm.c |  2 +-
 drivers/bus/Kconfig                |  6 ++--
 17 files changed, 86 insertions(+), 61 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 9e2d2adcc85b..ccd0d5553d38 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig

@@ -32,7 +32,7 @@ config ARM
 	select HANDLE_DOMAIN_IRQ
 	select HARDIRQS_SW_RESEND
 	select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT)
-	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
+	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7 || CPU_32_v7VE) && !CPU_32v6
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32
 	select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32
 	select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT)

@@ -46,12 +46,12 @@ config ARM
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32
-	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
+	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7VE) && MMU
 	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
 	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
 	select HAVE_GENERIC_DMA_COHERENT
-	select HAVE_HW_BREAKPOINT if (PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7))
+	select HAVE_HW_BREAKPOINT if (PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7VE))
 	select HAVE_IDE if PCI || ISA || PCMCIA
 	select HAVE_IRQ_TIME_ACCOUNTING
 	select HAVE_KERNEL_GZIP

@@ -805,6 +805,12 @@ config ARCH_MULTI_V7
 	select CPU_V7
 	select HAVE_SMP
 
+config ARCH_MULTI_V7VE
+	bool "ARMv7 w/ virtualization extensions based platforms (Cortex-A, PJ4-MP, Krait)"
+	select ARCH_MULTI_V6_V7
+	select CPU_V7VE
+	select HAVE_SMP
+
 config ARCH_MULTI_V6_V7
 	bool
 	select MIGHT_HAVE_CACHE_L2X0

@@ -1069,7 +1075,7 @@ config ARM_ERRATA_411920
 
 config ARM_ERRATA_430973
 	bool "ARM errata: Stale prediction on replaced interworking branch"
-	depends on CPU_V7
+	depends on CPU_V7 || CPU_V7VE