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| author | David S. Miller <davem@davemloft.net> | 2006-02-01 05:34:51 +0300 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2006-03-20 12:11:29 +0300 |
| commit | 86b818687d4894063ecd1190e54717a0cce8c009 (patch) | |
| tree | d2951295358502c88f7fe0c02517d729cff4eb9a /include/asm-sparc64/cpudata.h | |
| parent | 9954863975910a1b9372b7d5006a6cba43bdd288 (diff) | |
| download | linux-86b818687d4894063ecd1190e54717a0cce8c009.tar.xz | |
[SPARC64]: Fix race in LOAD_PER_CPU_BASE()
Since we use %g5 itself as a temporary, it can get clobbered
if we take an interrupt mid-stream and thus cause end up with
the final %g5 value too early as a result of rtrap processing.
Set %g5 at the very end, atomically, to avoid this problem.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/asm-sparc64/cpudata.h')
| -rw-r--r-- | include/asm-sparc64/cpudata.h | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/include/asm-sparc64/cpudata.h b/include/asm-sparc64/cpudata.h index 16d628913837..f83768883e98 100644 --- a/include/asm-sparc64/cpudata.h +++ b/include/asm-sparc64/cpudata.h @@ -101,20 +101,25 @@ extern void setup_tba(void); ldx [%g1 + %g6], %g6; /* Given the current thread info pointer in %g6, load the per-cpu - * area base of the current processor into %g5. REG1 and REG2 are + * area base of the current processor into %g5. REG1, REG2, and REG3 are * clobbered. + * + * You absolutely cannot use %g5 as a temporary in this code. The + * reason is that traps can happen during execution, and return from + * trap will load the fully resolved %g5 per-cpu base. This can corrupt + * the calculations done by the macro mid-stream. */ #ifdef CONFIG_SMP -#define LOAD_PER_CPU_BASE(REG1, REG2) \ +#define LOAD_PER_CPU_BASE(REG1, REG2, REG3) \ ldub [%g6 + TI_CPU], REG1; \ - sethi %hi(__per_cpu_shift), %g5; \ + sethi %hi(__per_cpu_shift), REG3; \ sethi %hi(__per_cpu_base), REG2; \ - ldx [%g5 + %lo(__per_cpu_shift)], %g5; \ + ldx [REG3 + %lo(__per_cpu_shift)], REG3; \ ldx [REG2 + %lo(__per_cpu_base)], REG2; \ - sllx REG1, %g5, %g5; \ - add %g5, REG2, %g5; + sllx REG1, REG3, REG3; \ + add REG3, REG2, %g5; #else -#define LOAD_PER_CPU_BASE(REG1, REG2) +#define LOAD_PER_CPU_BASE(REG1, REG2, REG3) #endif #endif /* _SPARC64_CPUDATA_H */ |