From: Christoph Hellwig <hch@lst.de>
To: Palmer Dabbelt <palmer@sifive.com>,
Paul Walmsley <paul.walmsley@sifive.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
Anup Patel <anup@brainfault.org>
Subject: [PATCH 09/12] riscv: clear the instruction cache and all registers when booting
Date: Mon, 28 Oct 2019 13:10:40 +0100 [thread overview]
Message-ID: <20191028121043.22934-10-hch@lst.de> (raw)
In-Reply-To: <20191028121043.22934-1-hch@lst.de>
When we get booted we want a clear slate without any leaks from previous
supervisors or the firmware. Flush the instruction cache and then clear
all registers to known good values. This is really important for the
upcoming nommu support that runs on M-mode, but can't really harm when
running in S-mode either. Vaguely based on the concepts from opensbi.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
---
arch/riscv/include/asm/csr.h | 1 +
arch/riscv/kernel/head.S | 88 +++++++++++++++++++++++++++++++++++-
2 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 318192c66fd8..0a62d2d68455 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -92,6 +92,7 @@
#define CSR_SATP 0x180
#define CSR_MSTATUS 0x300
+#define CSR_MISA 0x301
#define CSR_MIE 0x304
#define CSR_MTVEC 0x305
#define CSR_MSCRATCH 0x340
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index fc9973086946..64eb8beb228e 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -11,6 +11,7 @@
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/csr.h>
+#include <asm/hwcap.h>
#include <asm/image.h>
__INIT
@@ -51,12 +52,18 @@ _start_kernel:
csrw CSR_IP, zero
#ifdef CONFIG_RISCV_M_MODE
+ /* flush the instruction cache */
+ fence.i
+
+ /* Reset all registers except ra, a0, a1 */
+ call reset_regs
+
/*
* The hartid in a0 is expected later on, and we have no firmware
* to hand it to us.
*/
csrr a0, CSR_MHARTID
-#endif
+#endif /* CONFIG_RISCV_M_MODE */
/* Load the global pointer */
.option push
@@ -203,6 +210,85 @@ relocate:
j .Lsecondary_park
END(_start)
+#ifdef CONFIG_RISCV_M_MODE
+ENTRY(reset_regs)
+ li sp, 0
+ li gp, 0
+ li tp, 0
+ li t0, 0
+ li t1, 0
+ li t2, 0
+ li s0, 0
+ li s1, 0
+ li a2, 0
+ li a3, 0
+ li a4, 0
+ li a5, 0
+ li a6, 0
+ li a7, 0
+ li s2, 0
+ li s3, 0
+ li s4, 0
+ li s5, 0
+ li s6, 0
+ li s7, 0
+ li s8, 0
+ li s9, 0
+ li s10, 0
+ li s11, 0
+ li t3, 0
+ li t4, 0
+ li t5, 0
+ li t6, 0
+ csrw sscratch, 0
+
+#ifdef CONFIG_FPU
+ csrr t0, CSR_MISA
+ andi t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)
+ bnez t0, .Lreset_regs_done
+
+ li t1, SR_FS
+ csrs CSR_STATUS, t1
+ fmv.s.x f0, zero
+ fmv.s.x f1, zero
+ fmv.s.x f2, zero
+ fmv.s.x f3, zero
+ fmv.s.x f4, zero
+ fmv.s.x f5, zero
+ fmv.s.x f6, zero
+ fmv.s.x f7, zero
+ fmv.s.x f8, zero
+ fmv.s.x f9, zero
+ fmv.s.x f10, zero
+ fmv.s.x f11, zero
+ fmv.s.x f12, zero
+ fmv.s.x f13, zero
+ fmv.s.x f14, zero
+ fmv.s.x f15, zero
+ fmv.s.x f16, zero
+ fmv.s.x f17, zero
+ fmv.s.x f18, zero
+ fmv.s.x f19, zero
+ fmv.s.x f20, zero
+ fmv.s.x f21, zero
+ fmv.s.x f22, zero
+ fmv.s.x f23, zero
+ fmv.s.x f24, zero
+ fmv.s.x f25, zero
+ fmv.s.x f26, zero
+ fmv.s.x f27, zero
+ fmv.s.x f28, zero
+ fmv.s.x f29, zero
+ fmv.s.x f30, zero
+ fmv.s.x f31, zero
+ csrw fcsr, 0
+ /* note that the caller must clear SR_FS */
+#endif /* CONFIG_FPU */
+.Lreset_regs_done:
+ ret
+END(reset_regs)
+#endif /* CONFIG_RISCV_M_MODE */
+
__PAGE_ALIGNED_BSS
/* Empty zero page */
.balign PAGE_SIZE
--
2.20.1
next prev parent reply other threads:[~2019-10-28 12:11 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-28 12:10 RISC-V nommu support v6 Christoph Hellwig
2019-10-28 12:10 ` [PATCH 01/12] riscv: abstract out CSR names for supervisor vs machine mode Christoph Hellwig
2019-11-05 17:56 ` Paul Walmsley
2019-11-05 17:57 ` Paul Walmsley
2019-11-05 18:02 ` Marc Zyngier
2019-11-12 10:38 ` Thomas Gleixner
2019-11-14 7:30 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 02/12] riscv: don't allow selecting SBI based drivers for M-mode Christoph Hellwig
2019-11-14 7:31 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 03/12] riscv: poison SBI calls " Christoph Hellwig
2019-10-31 23:55 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 04/12] riscv: cleanup the default power off implementation Christoph Hellwig
2019-10-31 20:49 ` Paul Walmsley
2019-10-31 23:56 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 05/12] riscv: implement remote sfence.i using IPIs Christoph Hellwig
2019-10-31 23:57 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 06/12] riscv: add support for MMIO access to the timer registers Christoph Hellwig
2019-11-05 18:01 ` Paul Walmsley
2019-11-12 10:39 ` Thomas Gleixner
2019-11-17 23:06 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 07/12] riscv: provide native clint access for M-mode Christoph Hellwig
2019-10-28 12:10 ` [PATCH 08/12] riscv: read the hart ID from mhartid on boot Christoph Hellwig
2019-10-28 12:10 ` Christoph Hellwig [this message]
2019-11-14 7:45 ` [PATCH 09/12] riscv: clear the instruction cache and all registers when booting Paul Walmsley
2019-10-28 12:10 ` [PATCH 10/12] riscv: add nommu support Christoph Hellwig
2019-11-17 23:13 ` Paul Walmsley
2019-12-16 22:03 ` David Abdurachmanov
2019-12-17 3:18 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 11/12] riscv: provide a flat image loader Christoph Hellwig
2019-11-17 23:14 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 12/12] riscv: disable the EFI PECOFF header for M-mode Christoph Hellwig
2019-10-30 20:21 ` RISC-V nommu support v6 Paul Walmsley
2019-10-31 15:52 ` Christoph Hellwig
2019-10-31 20:13 ` Paul Walmsley
2019-11-23 2:19 ` Paul Walmsley
2019-12-11 8:42 ` Greentime Hu
2020-02-12 12:19 ` Greentime Hu
2019-11-11 9:47 ` Christoph Hellwig
2019-11-11 17:02 ` Paul Walmsley
2019-11-13 13:18 ` Christoph Hellwig
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