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authorLinus Torvalds <torvalds@linux-foundation.org>2019-10-04 13:02:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-10-04 13:02:47 -0700
commit812ad49d88b51fab551acb3c2d9c7d054bc69423 (patch)
tree6ef215b9b05ba8dedf76d2269cce3d015ddd952f
parenta4ad51e9528e614a60c8828901ee9d7b9f4538d5 (diff)
parent922b0375fc93fb1a20c5617e37c389c26bbccb70 (diff)
Merge tag 'riscv/for-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V fixes from Paul Walmsley: - Ensure that exclusive-load reservations are terminated after system call or exception handling. This primarily affects QEMU, which does not expire load reservations. - Fix an issue primarily affecting RV32 platforms that can cause the DT header to be corrupted, causing boot failures. * tag 'riscv/for-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: Fix memblock reservation for device tree blob RISC-V: Clear load reservations while restoring hart contexts
-rw-r--r--arch/riscv/include/asm/asm.h1
-rw-r--r--arch/riscv/kernel/entry.S21
-rw-r--r--arch/riscv/mm/init.c12
3 files changed, 32 insertions, 2 deletions
diff --git a/arch/riscv/include/asm/asm.h b/arch/riscv/include/asm/asm.h
index 5a02b7d50940..9c992a88d858 100644
--- a/arch/riscv/include/asm/asm.h
+++ b/arch/riscv/include/asm/asm.h
@@ -22,6 +22,7 @@
#define REG_L __REG_SEL(ld, lw)
#define REG_S __REG_SEL(sd, sw)
+#define REG_SC __REG_SEL(sc.d, sc.w)
#define SZREG __REG_SEL(8, 4)
#define LGREG __REG_SEL(3, 2)
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index da7aa88113c2..2d592da1e776 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -98,7 +98,26 @@ _save_context:
*/
.macro RESTORE_ALL
REG_L a0, PT_SSTATUS(sp)
- REG_L a2, PT_SEPC(sp)
+ /*
+ * The current load reservation is effectively part of the processor's
+ * state, in the sense that load reservations cannot be shared between
+ * different hart contexts. We can't actually save and restore a load
+ * reservation, so instead here we clear any existing reservation --
+ * it's always legal for implementations to clear load reservations at
+ * any point (as long as the forward progress guarantee is kept, but
+ * we'll ignore that here).
+ *
+ * Dangling load reservations can be the result of taking a trap in the
+ * middle of an LR/SC sequence, but can also be the result of a taken
+ * forward branch around an SC -- which is how we implement CAS. As a
+ * result we need to clear reservations between the last CAS and the
+ * jump back to the new context. While it is unlikely the store
+ * completes, implementations are allowed to expand reservations to be
+ * arbitrarily large.
+ */
+ REG_L a2, PT_SEPC(sp)
+ REG_SC x0, a2, PT_SEPC(sp)
+
csrw CSR_SSTATUS, a0
csrw CSR_SEPC, a2
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index f0ba71304b6e..83f7d12042fb 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -11,6 +11,7 @@
#include <linux/swap.h>
#include <linux/sizes.h>
#include <linux/of_fdt.h>
+#include <linux/libfdt.h>
#include <asm/fixmap.h>
#include <asm/tlbflush.h>
@@ -82,6 +83,8 @@ disable:
}
#endif /* CONFIG_BLK_DEV_INITRD */
+static phys_addr_t dtb_early_pa __initdata;
+
void __init setup_bootmem(void)
{
struct memblock_region *reg;
@@ -117,7 +120,12 @@ void __init setup_bootmem(void)
setup_initrd();
#endif /* CONFIG_BLK_DEV_INITRD */
- early_init_fdt_reserve_self();
+ /*
+ * Avoid using early_init_fdt_reserve_self() since __pa() does
+ * not work for DTB pointers that are fixmap addresses
+ */
+ memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
+
early_init_fdt_scan_reserved_mem();
memblock_allow_resize();
memblock_dump_all();
@@ -393,6 +401,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
/* Save pointer to DTB for early FDT parsing */
dtb_early_va = (void *)fix_to_virt(FIX_FDT) + (dtb_pa & ~PAGE_MASK);
+ /* Save physical address for memblock reservation */
+ dtb_early_pa = dtb_pa;
}
static void __init setup_vm_final(void)