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RISC-V updates for v5.4-rc2 

Two RISC-V fixes for v5.4-rc2:
 
 - 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.
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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
This commit is contained in:
Linus Torvalds 2019-10-04 13:02:47 -07:00
parent a4ad51e952 922b0375fc
commit 812ad49d88
3 changed files with 32 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/riscv/include/asm/asm.h
View File

@ -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)

19
arch/riscv/kernel/entry.S
View File

@ -98,7 +98,26 @@ _save_context:
*/
.macro RESTORE_ALL
REG_L a0, PT_SSTATUS(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

12
arch/riscv/mm/init.c
View File

@ -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 @@ static void __init setup_initrd(void)
}
#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)