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| author | Vasily Gorbik <gor@linux.ibm.com> | 2024-08-28 19:06:49 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2024-08-29 22:56:34 +0200 |
| commit | bb91ed0ee3a76406846b99d6aca8121100a14ff5 (patch) | |
| tree | 3a7612b2fdc8e6ade1ff8962c82a93fbec252564 | |
| parent | ee3daf7c05e70a0b88723ceb18587aed75716729 (diff) | |
| download | lwn-bb91ed0ee3a76406846b99d6aca8121100a14ff5.tar.gz lwn-bb91ed0ee3a76406846b99d6aca8121100a14ff5.zip | |
s390/setup: Recognize sequential instruction fetching facility
When sequential instruction fetching facility is present,
certain guarantees are provided for code patching. In particular,
atomic overwrites within 8 aligned bytes is safe from an
instruction-fetching point of view.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/setup.h | 2 | ||||
| -rw-r--r-- | arch/s390/kernel/early.c | 2 |
2 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h index 50b943f30155..70b920b32827 100644 --- a/arch/s390/include/asm/setup.h +++ b/arch/s390/include/asm/setup.h @@ -34,6 +34,7 @@ #define MACHINE_FLAG_SCC BIT(17) #define MACHINE_FLAG_PCI_MIO BIT(18) #define MACHINE_FLAG_RDP BIT(19) +#define MACHINE_FLAG_SEQ_INSN BIT(20) #define LPP_MAGIC BIT(31) #define LPP_PID_MASK _AC(0xffffffff, UL) @@ -95,6 +96,7 @@ extern unsigned long mio_wb_bit_mask; #define MACHINE_HAS_SCC (get_lowcore()->machine_flags & MACHINE_FLAG_SCC) #define MACHINE_HAS_PCI_MIO (get_lowcore()->machine_flags & MACHINE_FLAG_PCI_MIO) #define MACHINE_HAS_RDP (get_lowcore()->machine_flags & MACHINE_FLAG_RDP) +#define MACHINE_HAS_SEQ_INSN (get_lowcore()->machine_flags & MACHINE_FLAG_SEQ_INSN) /* * Console mode. Override with conmode= diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index cc4264d23019..62f8f5a750a3 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -268,6 +268,8 @@ static __init void detect_machine_facilities(void) } if (test_facility(194)) get_lowcore()->machine_flags |= MACHINE_FLAG_RDP; + if (test_facility(85)) + get_lowcore()->machine_flags |= MACHINE_FLAG_SEQ_INSN; } static inline void save_vector_registers(void) |