From 3338a65badd5758c8723e2b1e5a0db88151f2774 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Mon, 23 Feb 2015 16:14:37 +0100 Subject: [PATCH] powerpc/vphn: parsing code rewrite The current VPHN parsing logic has some flaws that this patch aims to fix: 1) when the value 0xffff is read, the value 0xffffffff gets added to the the output list and its element count isn't incremented. This is wrong. According to PAPR+ the domain identifiers are packed into a sequence terminated by the "reserved value of all ones". This means that 0xffff is a stream terminator. 2) the combination of byteswaps and casts make the code hardly readable. Let's parse the stream one 16-bit field at a time instead. 3) it is assumed that the hypercall returns 12 32-bit values packed into 6 64-bit registers. According to PAPR+, the domain identifiers may be streamed as 16-bit values. Let's increase the number of expected numbers to 24. Signed-off-by: Greg Kurz Signed-off-by: Michael Ellerman --- arch/powerpc/mm/vphn.c | 54 +++++++++++++++++++++++++++++------------- arch/powerpc/mm/vphn.h | 6 ++--- 2 files changed, 40 insertions(+), 20 deletions(-) diff --git a/arch/powerpc/mm/vphn.c b/arch/powerpc/mm/vphn.c index c49ed519c381..5f8ef50e5c66 100644 --- a/arch/powerpc/mm/vphn.c +++ b/arch/powerpc/mm/vphn.c @@ -2,44 +2,64 @@ #include "vphn.h" /* - * Convert the associativity domain numbers returned from the hypervisor - * to the sequence they would appear in the ibm,associativity property. + * The associativity domain numbers are returned from the hypervisor as a + * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the + * special value of "all ones" (aka. 0xffff) and its size may not exceed 48 + * bytes. + * + * --- 16-bit fields --> + * _________________________ + * | 0 | 1 | 2 | 3 | be_packed[0] + * ------+-----+-----+------ + * _________________________ + * | 4 | 5 | 6 | 7 | be_packed[1] + * ------------------------- + * ... + * _________________________ + * | 20 | 21 | 22 | 23 | be_packed[5] + * ------------------------- + * + * Convert to the sequence they would appear in the ibm,associativity property. */ int vphn_unpack_associativity(const long *packed, __be32 *unpacked) { __be64 be_packed[VPHN_REGISTER_COUNT]; int i, nr_assoc_doms = 0; const __be16 *field = (const __be16 *) be_packed; + u16 last = 0; + bool is_32bit = false; #define VPHN_FIELD_UNUSED (0xffff) #define VPHN_FIELD_MSB (0x8000) #define VPHN_FIELD_MASK (~VPHN_FIELD_MSB) - /* Let's recreate the original stream. */ + /* Let's fix the values returned by plpar_hcall9() */ for (i = 0; i < VPHN_REGISTER_COUNT; i++) be_packed[i] = cpu_to_be64(packed[i]); for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) { - if (be16_to_cpup(field) == VPHN_FIELD_UNUSED) { - /* All significant fields processed, and remaining - * fields contain the reserved value of all 1's. - * Just store them. + u16 new = be16_to_cpup(field++); + + if (is_32bit) { + /* Let's concatenate the 16 bits of this field to the + * 15 lower bits of the previous field */ - unpacked[i] = *((__be32 *)field); - field += 2; - } else if (be16_to_cpup(field) & VPHN_FIELD_MSB) { + unpacked[++nr_assoc_doms] = + cpu_to_be32(last << 16 | new); + is_32bit = false; + } else if (new == VPHN_FIELD_UNUSED) + /* This is the list terminator */ + break; + else if (new & VPHN_FIELD_MSB) { /* Data is in the lower 15 bits of this field */ - unpacked[i] = cpu_to_be32( - be16_to_cpup(field) & VPHN_FIELD_MASK); - field++; - nr_assoc_doms++; + unpacked[++nr_assoc_doms] = + cpu_to_be32(new & VPHN_FIELD_MASK); } else { /* Data is in the lower 15 bits of this field * concatenated with the next 16 bit field */ - unpacked[i] = *((__be32 *)field); - field += 2; - nr_assoc_doms++; + last = new; + is_32bit = true; } } diff --git a/arch/powerpc/mm/vphn.h b/arch/powerpc/mm/vphn.h index 96af9a474693..fe8b7805b78f 100644 --- a/arch/powerpc/mm/vphn.h +++ b/arch/powerpc/mm/vphn.h @@ -6,10 +6,10 @@ #define VPHN_REGISTER_COUNT 6 /* - * 6 64-bit registers unpacked into 12 32-bit associativity values. To form - * the complete property we have to add the length in the first cell. + * 6 64-bit registers unpacked into up to 24 be32 associativity values. To + * form the complete property we have to add the length in the first cell. */ -#define VPHN_ASSOC_BUFSIZE (VPHN_REGISTER_COUNT*sizeof(u64)/sizeof(u32) + 1) +#define VPHN_ASSOC_BUFSIZE (VPHN_REGISTER_COUNT*sizeof(u64)/sizeof(u16) + 1) extern int vphn_unpack_associativity(const long *packed, __be32 *unpacked); -- 2.20.1