diff options
Diffstat (limited to 'arch/arm64/kernel/armv8_deprecated.c')
| -rw-r--r-- | arch/arm64/kernel/armv8_deprecated.c | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 42ffdb54e162..b0988bb1bf64 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -280,35 +280,43 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table) /* * Error-checking SWP macros implemented using ldxr{b}/stxr{b} */ -#define __user_swpX_asm(data, addr, res, temp, B) \ + +/* Arbitrary constant to ensure forward-progress of the LL/SC loop */ +#define __SWP_LL_SC_LOOPS 4 + +#define __user_swpX_asm(data, addr, res, temp, temp2, B) \ __asm__ __volatile__( \ + " mov %w3, %w7\n" \ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) \ - "0: ldxr"B" %w2, [%3]\n" \ - "1: stxr"B" %w0, %w1, [%3]\n" \ + "0: ldxr"B" %w2, [%4]\n" \ + "1: stxr"B" %w0, %w1, [%4]\n" \ " cbz %w0, 2f\n" \ - " mov %w0, %w4\n" \ + " sub %w3, %w3, #1\n" \ + " cbnz %w3, 0b\n" \ + " mov %w0, %w5\n" \ " b 3f\n" \ "2:\n" \ " mov %w1, %w2\n" \ "3:\n" \ " .pushsection .fixup,\"ax\"\n" \ " .align 2\n" \ - "4: mov %w0, %w5\n" \ + "4: mov %w0, %w6\n" \ " b 3b\n" \ " .popsection" \ _ASM_EXTABLE(0b, 4b) \ _ASM_EXTABLE(1b, 4b) \ ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) \ - : "=&r" (res), "+r" (data), "=&r" (temp) \ - : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT) \ + : "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \ + : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT), \ + "i" (__SWP_LL_SC_LOOPS) \ : "memory") -#define __user_swp_asm(data, addr, res, temp) \ - __user_swpX_asm(data, addr, res, temp, "") -#define __user_swpb_asm(data, addr, res, temp) \ - __user_swpX_asm(data, addr, res, temp, "b") +#define __user_swp_asm(data, addr, res, temp, temp2) \ + __user_swpX_asm(data, addr, res, temp, temp2, "") +#define __user_swpb_asm(data, addr, res, temp, temp2) \ + __user_swpX_asm(data, addr, res, temp, temp2, "b") /* * Bit 22 of the instruction encoding distinguishes between @@ -328,12 +336,12 @@ static int emulate_swpX(unsigned int address, unsigned int *data, } while (1) { - unsigned long temp; + unsigned long temp, temp2; if (type == TYPE_SWPB) - __user_swpb_asm(*data, address, res, temp); + __user_swpb_asm(*data, address, res, temp, temp2); else - __user_swp_asm(*data, address, res, temp); + __user_swp_asm(*data, address, res, temp, temp2); if (likely(res != -EAGAIN) || signal_pending(current)) break; |