From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Morse Subject: [PATCH v3 03/10] arm64: Add new hcall HVC_CALL_FUNC Date: Thu, 26 Nov 2015 17:32:41 +0000 Message-ID: <1448559168-8363-4-git-send-email-james.morse@arm.com> References: <1448559168-8363-1-git-send-email-james.morse@arm.com> Return-path: Received: from foss.arm.com ([217.140.101.70]:46246 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274AbbKZReA (ORCPT ); Thu, 26 Nov 2015 12:34:00 -0500 In-Reply-To: <1448559168-8363-1-git-send-email-james.morse@arm.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: linux-arm-kernel@lists.infradead.org Cc: Will Deacon , Sudeep Holla , Kevin Kang , Geoff Levand , Catalin Marinas , Lorenzo Pieralisi , Mark Rutland , AKASHI Takahiro , wangfei , Marc Zyngier , "Rafael J . Wysocki" , Pavel Machek , linux-pm@vger.kernel.org, James Morse From: Geoff Levand Add the new hcall HVC_CALL_FUNC that allows execution of a function at EL2. During CPU reset the CPU must be brought to the exception level it had on entry to the kernel. The HVC_CALL_FUNC hcall will provide the mechanism needed for this exception level switch. To allow the HVC_CALL_FUNC exception vector to work without a stack, which is needed to support an hcall at CPU reset, this implementation uses register x18 to store the link register across the caller provided function. This dictates that the caller provided function must preserve the contents of register x18. Signed-off-by: Geoff Levand Signed-off-by: James Morse --- arch/arm64/include/asm/virt.h | 13 +++++++++++++ arch/arm64/kernel/hyp-stub.S | 13 ++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index eb10368c329e..30700961f28c 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -45,6 +45,19 @@ #define HVC_SET_VECTORS 2 +/* + * HVC_CALL_FUNC - Execute a function at EL2. + * + * @x0: Physical address of the function to be executed. + * @x1: Passed as the first argument to the function. + * @x2: Passed as the second argument to the function. + * @x3: Passed as the third argument to the function. + * + * The called function must preserve the contents of register x18. + */ + +#define HVC_CALL_FUNC 3 + #define BOOT_CPU_MODE_EL1 (0xe11) #define BOOT_CPU_MODE_EL2 (0xe12) diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index 017ab519aaf1..e8febe90c036 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -67,8 +67,19 @@ el1_sync: b 2f 1: cmp x18, #HVC_SET_VECTORS - b.ne 2f + b.ne 1f msr vbar_el2, x0 + b 2f + +1: cmp x18, #HVC_CALL_FUNC + b.ne 2f + mov x18, lr + mov lr, x0 + mov x0, x1 + mov x1, x2 + mov x2, x3 + blr lr + mov lr, x18 2: eret ENDPROC(el1_sync) -- 2.6.2