[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 10/16] livepatch: x86, ARM, alternative: Expose FEATURE_LIVEPATCH
Hi Konrad, On 16/09/2016 18:38, Konrad Rzeszutek Wilk wrote: To use as a common way of testing alternative patching for livepatches. Both architectures have this FEATURE and the test-cases can piggyback on that. Suggested-by: Julien Grall <julien.grall@xxxxxxx> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> --- Cc: Julien Grall <julien.grall@xxxxxxx> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx> Cc: Jan Beulich <jbeulich@xxxxxxxx> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> v3: New submission v4: Move the LIVEPATCH_FEATURE to asm-x86/livepatch.h --- xen/arch/arm/livepatch.c | 3 +++ xen/include/asm-arm/alternative.h | 2 ++ xen/include/asm-arm/cpufeature.h | 5 +++++ xen/include/asm-x86/livepatch.h | 1 + xen/test/livepatch/xen_hello_world_func.c | 8 +++++--- 5 files changed, 16 insertions(+), 3 deletions(-) diff --git a/xen/arch/arm/livepatch.c b/xen/arch/arm/livepatch.c index 13d6c10..b771cb7 100644 --- a/xen/arch/arm/livepatch.c +++ b/xen/arch/arm/livepatch.c @@ -8,6 +8,7 @@ #include <xen/livepatch.h> #include <xen/vmap.h> +#include <asm/cpufeature.h> #include <asm/livepatch.h> #include <asm/mm.h> @@ -175,6 +176,8 @@ void __init arch_livepatch_init(void) end = (void *)LIVEPATCH_VMAP_END; vm_init_type(VMAP_XEN, start, end); + + cpus_set_cap(LIVEPATCH_FEATURE); } /* diff --git a/xen/include/asm-arm/alternative.h b/xen/include/asm-arm/alternative.h index 6851217..cca5f17 100644 --- a/xen/include/asm-arm/alternative.h +++ b/xen/include/asm-arm/alternative.h @@ -165,6 +165,8 @@ static inline int apply_alternatives(void *start, size_t lenght) return 0; } +#define ALTERNATIVE(oldinstr, newinstr, ...) "" + Why this change? Nobody should ever use ALTERNATIVE when CONFIG_ALTERNATIVE is not enabled. This is a call to have a Xen not patched for a buggy hardware. Not to mention that a void ALTERNATIVE is really buggy. We use ALTERNATIVE to switch between two set of instructions. So we always need at least one integrated in Xen. #endif #endif /* __ASM_ALTERNATIVE_H */ diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h index 66e930f..19e768b 100644 --- a/xen/include/asm-arm/cpufeature.h +++ b/xen/include/asm-arm/cpufeature.h @@ -40,7 +40,12 @@ #define ARM32_WORKAROUND_766422 2 #define ARM64_WORKAROUND_834220 3 +#ifdef CONFIG_LIVEPATCH +#define LIVEPATCH_FEATURE 4 +#define ARM_NCAPS 5 +#else #define ARM_NCAPS 4 +#endif I would rather define the feature livepatch unconditionally to avoid the definition of ARM_NCAPS twice. diff --git a/xen/test/livepatch/xen_hello_world_func.c b/xen/test/livepatch/xen_hello_world_func.c index 6f53ab4..765a871 100644 --- a/xen/test/livepatch/xen_hello_world_func.c +++ b/xen/test/livepatch/xen_hello_world_func.c @@ -20,7 +20,6 @@ const char *xen_hello_world(void) unsigned long tmp; int rc; - alternative(ASM_NOP8, ASM_NOP1, X86_FEATURE_LM); Any reason to move the code later on? /* * Any BUG, or WARN_ON will contain symbol and payload name. Furthermore * exceptions will be caught and processed properly. @@ -28,8 +27,11 @@ const char *xen_hello_world(void) rc = __get_user(tmp, non_canonical_addr); BUG_ON(rc != -EFAULT); #endif -#ifdef CONFIG_ARM_64 - asm(ALTERNATIVE("nop", "nop", ARM64_WORKAROUND_CLEAN_CACHE)); +#ifdef CONFIG_ARM + asm(ALTERNATIVE("nop", "nop", LIVEPATCH_FEATURE)); Ah, this is why you need a nop ALTERNATIVE. My comment above still stands, this definition of ALTERNATIVE maybe be valid for your use case, but it is invalid for most of the others. +#endif +#ifdef CONFIG_X86 + asm(ALTERNATIVE(ASM_NOP8, ASM_NOP1, LIVEPATCH_FEATURE)); #endif return "Hello World"; } Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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