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| author | Heiher <r@hev.cc> | 2018-06-11 17:01:10 +0800 |
|---|---|---|
| committer | Paul Burton <paul.burton@mips.com> | 2018-06-24 09:27:27 -0700 |
| commit | c8bf38055efaf764fd8c313695759c64dc735842 (patch) | |
| tree | 01514c17094ee3154485f4b1888492f319c4cd83 | |
| parent | be462bd9700aec12029d43d48e6ff2207cb68fb7 (diff) | |
| download | linux-c8bf38055efaf764fd8c313695759c64dc735842.tar.gz linux-c8bf38055efaf764fd8c313695759c64dc735842.tar.bz2 linux-c8bf38055efaf764fd8c313695759c64dc735842.zip | |
MIPS: Fix ejtag handler on SMP
On SMP systems, the shared ejtag debug buffer may be overwritten by
other cores, because every cores can generate ejtag exception at
same time.
Unfortunately, in that context, it's difficult to relax more registers
to access per cpu buffers. so use ll/sc to serialize the access.
[paul.burton@mips.com:
This could in theory be backported at least as far back as the
beginning of the git era, however in general it's exceedingly rare
that anyone would hit this without further changes, so it doesn't seem
worthwhile marking for backport.]
Signed-off-by: Heiher <r@hev.cc>
Patchwork: https://patchwork.linux-mips.org/patch/19507/
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: jhogan@kernel.org
Cc: ralf@linux-mips.org
| -rw-r--r-- | arch/mips/kernel/genex.S | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S index 37b9383eacd3..6c257b52f57f 100644 --- a/arch/mips/kernel/genex.S +++ b/arch/mips/kernel/genex.S @@ -354,16 +354,56 @@ NESTED(ejtag_debug_handler, PT_SIZE, sp) sll k0, k0, 30 # Check for SDBBP. bgez k0, ejtag_return +#ifdef CONFIG_SMP +1: PTR_LA k0, ejtag_debug_buffer_spinlock + ll k0, 0(k0) + bnez k0, 1b + PTR_LA k0, ejtag_debug_buffer_spinlock + sc k0, 0(k0) + beqz k0, 1b +# ifdef CONFIG_WEAK_REORDERING_BEYOND_LLSC + sync +# endif + + PTR_LA k0, ejtag_debug_buffer + LONG_S k1, 0(k0) + + ASM_CPUID_MFC0 k1, ASM_SMP_CPUID_REG + PTR_SRL k1, SMP_CPUID_PTRSHIFT + PTR_SLL k1, LONGLOG + PTR_LA k0, ejtag_debug_buffer_per_cpu + PTR_ADDU k0, k1 + + PTR_LA k1, ejtag_debug_buffer + LONG_L k1, 0(k1) + LONG_S k1, 0(k0) + + PTR_LA k0, ejtag_debug_buffer_spinlock + sw zero, 0(k0) +#else PTR_LA k0, ejtag_debug_buffer LONG_S k1, 0(k0) +#endif + SAVE_ALL move a0, sp jal ejtag_exception_handler RESTORE_ALL + +#ifdef CONFIG_SMP + ASM_CPUID_MFC0 k1, ASM_SMP_CPUID_REG + PTR_SRL k1, SMP_CPUID_PTRSHIFT + PTR_SLL k1, LONGLOG + PTR_LA k0, ejtag_debug_buffer_per_cpu + PTR_ADDU k0, k1 + LONG_L k1, 0(k0) +#else PTR_LA k0, ejtag_debug_buffer LONG_L k1, 0(k0) +#endif ejtag_return: + back_to_back_c0_hazard MFC0 k0, CP0_DESAVE .set mips32 deret @@ -377,6 +417,12 @@ ejtag_return: .data EXPORT(ejtag_debug_buffer) .fill LONGSIZE +#ifdef CONFIG_SMP +EXPORT(ejtag_debug_buffer_spinlock) + .fill LONGSIZE +EXPORT(ejtag_debug_buffer_per_cpu) + .fill LONGSIZE * NR_CPUS +#endif .previous __INIT |