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| author |   Sven Schnelle <svens@linux.ibm.com> | 2021-04-07 09:20:17 +0200 |
|---|---|---|
| committer |   Vasily Gorbik <gor@linux.ibm.com> | 2021-10-26 15:21:29 +0200 |
| commit | 3b051e89da70d464a036a86d70ce2ed61c73f792 (patch) | |
| tree | ad9a4dc6ce89d26aaf92d530d48df8e992c629e6 /arch/s390/include/asm | |
| parent | s390: introduce nospec_uses_trampoline() (diff) | |
| download | linux-dev-3b051e89da70d464a036a86d70ce2ed61c73f792.tar.xz linux-dev-3b051e89da70d464a036a86d70ce2ed61c73f792.zip | |
s390: add support for BEAR enhancement facility
The Breaking-Event-Address-Register (BEAR) stores the address of the
last breaking event instruction. Breaking events are usually instructions
that change the program flow - for example branches, and instructions
that modify the address in the PSW like lpswe. This is useful for debugging
wild branches, because one could easily figure out where the wild branch
was originating from.
What is problematic is that lpswe is considered a breaking event, and
therefore overwrites BEAR on kernel exit. The BEAR enhancement facility
adds new instructions that allow to save/restore BEAR and also an lpswey
instruction that doesn't cause a breaking event. So we can save BEAR on
kernel entry and restore it on exit to user space.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include/asm')
| -rw-r--r-- | arch/s390/include/asm/cpu.h | 3 | ||||
| -rw-r--r-- | arch/s390/include/asm/lowcore.h | 7 |
2 files changed, 7 insertions, 3 deletions
diff --git a/arch/s390/include/asm/cpu.h b/arch/s390/include/asm/cpu.h index 62228a884e06..26c710cd3485 100644 --- a/arch/s390/include/asm/cpu.h +++ b/arch/s390/include/asm/cpu.h @@ -12,6 +12,7 @@ #ifndef __ASSEMBLY__ #include <linux/types.h> +#include <linux/jump_label.h> struct cpuid { @@ -21,5 +22,7 @@ struct cpuid unsigned int unused : 16; } __attribute__ ((packed, aligned(8))); +DECLARE_STATIC_KEY_FALSE(cpu_has_bear); + #endif /* __ASSEMBLY__ */ #endif /* _ASM_S390_CPU_H */ diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h index 1129a1e93e80..1262f5003acf 100644 --- a/arch/s390/include/asm/lowcore.h +++ b/arch/s390/include/asm/lowcore.h @@ -93,9 +93,10 @@ struct lowcore { psw_t return_psw; /* 0x0290 */ psw_t return_mcck_psw; /* 0x02a0 */ + __u64 last_break; /* 0x02b0 */ + /* CPU accounting and timing values. */ - __u64 sys_enter_timer; /* 0x02b0 */ - __u8 pad_0x02b8[0x02c0-0x02b8]; /* 0x02b8 */ + __u64 sys_enter_timer; /* 0x02b8 */ __u64 mcck_enter_timer; /* 0x02c0 */ __u64 exit_timer; /* 0x02c8 */ __u64 user_timer; /* 0x02d0 */ @@ -188,7 +189,7 @@ struct lowcore { __u32 tod_progreg_save_area; /* 0x1324 */ __u32 cpu_timer_save_area[2]; /* 0x1328 */ __u32 clock_comp_save_area[2]; /* 0x1330 */ - __u8 pad_0x1338[0x1340-0x1338]; /* 0x1338 */ + __u64 last_break_save_area; /* 0x1338 */ __u32 access_regs_save_area[16]; /* 0x1340 */ __u64 cregs_save_area[16]; /* 0x1380 */ __u8 pad_0x1400[0x1800-0x1400]; /* 0x1400 */ |