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Message-ID: <20130402212204.GA30438@linux.vnet.ibm.com>
Date: Tue, 2 Apr 2013 14:22:05 -0700
From: Nishanth Aravamudan <nacc@...ux.vnet.ibm.com>
To: benh@...nel.crashing.org
Cc: Ryan Arnold <ryanarn@...ibm.com>,
Steve Munroe <sjmunroe@...ibm.com>, michaele@....ibm.com,
paulus@...ba.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] powerpc: Add HWCAP2 aux entry
From: Michael Neuling <michael.neuling@....ibm.com>
We are currently out of free bits in AT_HWCAP. With POWER8, we have
several hardware features that we need to advertise. Tested on POWER and
x86.
Signed-off-by: Michael Neuling <michael.neuling@....ibm.com>
Signed-off-by: Nishanth Aravamudan <nacc@...ux.vnet.ibm.com>
diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index fb3245e..ccadad6 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -52,6 +52,7 @@ struct cpu_spec {
char *cpu_name;
unsigned long cpu_features; /* Kernel features */
unsigned int cpu_user_features; /* Userland features */
+ unsigned int cpu_user_features2; /* Userland features v2 */
unsigned int mmu_features; /* MMU features */
/* cache line sizes */
diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index ac9790f..cc0655a 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -61,6 +61,7 @@ typedef elf_vrregset_t elf_fpxregset_t;
instruction set this cpu supports. This could be done in userspace,
but it's not easy, and we've already done it here. */
# define ELF_HWCAP (cur_cpu_spec->cpu_user_features)
+# define ELF_HWCAP2 (cur_cpu_spec->cpu_user_features2)
/* This yields a string that ld.so will use to load implementation
specific libraries for optimization. This is more specific in
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 3939829..51adc23 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -140,6 +140,13 @@ static int padzero(unsigned long elf_bss)
#define ELF_BASE_PLATFORM NULL
#endif
+/*
+ * Most archs don't need this
+ */
+#ifndef ELF_HWCAP2
+#define ELF_HWCAP2 (0)
+#endif
+
static int
create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
unsigned long load_addr, unsigned long interp_load_addr)
@@ -240,6 +247,7 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
NEW_AUX_ENT(AT_EGID, from_kgid_munged(cred->user_ns, cred->egid));
NEW_AUX_ENT(AT_SECURE, security_bprm_secureexec(bprm));
NEW_AUX_ENT(AT_RANDOM, (elf_addr_t)(unsigned long)u_rand_bytes);
+ NEW_AUX_ENT(AT_HWCAP2, ELF_HWCAP2);
NEW_AUX_ENT(AT_EXECFN, bprm->exec);
if (k_platform) {
NEW_AUX_ENT(AT_PLATFORM,
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 9c13e02..0b553d3 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -469,6 +469,13 @@ error_kill:
#endif
/*
+ * Most archs don't need this
+ */
+#ifndef ELF_HWCAP2
+#define ELF_HWCAP2 (0)
+#endif
+
+/*
* present useful information to the program by shovelling it onto the new
* process's stack
*/
@@ -483,7 +490,6 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
size_t platform_len = 0, len;
char *k_platform, *k_base_platform;
char __user *u_platform, *u_base_platform, *p;
- long hwcap;
int loop;
int nr; /* reset for each csp adjustment */
@@ -502,8 +508,6 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
return -EFAULT;
#endif
- hwcap = ELF_HWCAP;
-
/*
* If this architecture has a platform capability string, copy it
* to userspace. In some cases (Sparc), this info is impossible
@@ -617,7 +621,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
nr = 0;
csp -= DLINFO_ITEMS * 2 * sizeof(unsigned long);
- NEW_AUX_ENT(AT_HWCAP, hwcap);
+ NEW_AUX_ENT(AT_HWCAP, ELF_HWCAP);
+ NEW_AUX_ENT(AT_HWCAP2, ELF_HWCAP2);
NEW_AUX_ENT(AT_PAGESZ, PAGE_SIZE);
NEW_AUX_ENT(AT_CLKTCK, CLOCKS_PER_SEC);
NEW_AUX_ENT(AT_PHDR, exec_params->ph_addr);
diff --git a/include/uapi/linux/auxvec.h b/include/uapi/linux/auxvec.h
index 61594d5..835c065 100644
--- a/include/uapi/linux/auxvec.h
+++ b/include/uapi/linux/auxvec.h
@@ -28,6 +28,7 @@
#define AT_BASE_PLATFORM 24 /* string identifying real platform, may
* differ from AT_PLATFORM. */
#define AT_RANDOM 25 /* address of 16 random bytes */
+#define AT_HWCAP2 26 /* extension of AT_HWCAP */
#define AT_EXECFN 31 /* filename of program */
--
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