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Message-ID: <54356444.1080702@linux.vnet.ibm.com>
Date: Wed, 08 Oct 2014 21:50:20 +0530
From: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
CC: linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org,
peterz@...radead.org, akpm@...ux-foundation.org,
tglx@...utronix.de, mikey@...ling.org, james.hogan@...tec.com,
avagin@...nvz.org, Paul.Clothier@...tec.com, palves@...hat.com,
oleg@...hat.com, dhowells@...hat.com, davej@...hat.com,
davem@...emloft.net
Subject: Re: [PATCH V3 3/3] powerpc, ptrace: Enable support for miscellaneous
registers
On 08/28/2014 03:05 AM, Sukadev Bhattiprolu wrote:
>
> Anshuman Khandual [khandual@...ux.vnet.ibm.com] wrote:
> | This patch enables get and set of miscellaneous registers through ptrace
> | PTRACE_GETREGSET/PTRACE_SETREGSET interface by implementing new powerpc
> | specific register set REGSET_MISC support corresponding to the new ELF
> | core note NT_PPC_MISC added previously in this regard.
> |
> | Signed-off-by: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
> | ---
> | arch/powerpc/kernel/ptrace.c | 81 ++++++++++++++++++++++++++++++++++++++++++++
> | 1 file changed, 81 insertions(+)
> |
> | diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> | index 17642ef..63b883a 100644
> | --- a/arch/powerpc/kernel/ptrace.c
> | +++ b/arch/powerpc/kernel/ptrace.c
> | @@ -1149,6 +1149,76 @@ static int tm_cvmx_set(struct task_struct *target, const struct user_regset *reg
> | #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
> |
> | /*
> | + * Miscellaneous Registers
> | + *
> | + * struct {
> | + * unsigned long dscr;
> | + * unsigned long ppr;
> | + * unsigned long tar;
> | + * };
> | + */
> | +static int misc_get(struct task_struct *target, const struct user_regset *regset,
> | + unsigned int pos, unsigned int count,
> | + void *kbuf, void __user *ubuf)
> | +{
> | + int ret;
> | +
> | + /* DSCR register */
> | + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | + &target->thread.dscr, 0,
> | + sizeof(unsigned long));
> | +
> | + BUILD_BUG_ON(offsetof(struct thread_struct, dscr) + sizeof(unsigned long) +
> | + sizeof(unsigned long) != offsetof(struct thread_struct, ppr));
>
>
> I see these in arch/powerpc/include/asm/processor.h
>
> #ifdef CONFIG_PPC64
> unsigned long dscr;
> int dscr_inherit;
> unsigned long ppr; /* used to save/restore SMT priority */
> #endif
>
> where there is an 'int' between ppr and dscr. So, should one of
> the above sizeof(unsigned long) be changed to sizeof(int) ?
Right, I understand that but strangely I get this compile time error
when it is changed to sizeof(int).
error: call to ‘__compiletime_assert_1350’ declared with attribute error:
BUILD_BUG_ON failed: TSO(dscr) + sizeof(unsigned long) + sizeof(int) != TSO(ppr)
BUILD_BUG_ON(TSO(dscr) + sizeof(unsigned long) + sizeof(int) != TSO(ppr));
may be I am missing something here.
>
> Also, since we use offsetof(struct thread_struct, field) heavily, a
> macro local to the file, may simplify the code.
Right, will do that.
> #define TSO(f) (offsetof(struct thread_struct, f))
>
> | +
> | + /* PPR register */
> | + if (!ret)
> | + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | + &target->thread.ppr, sizeof(unsigned long),
> | + 2 * sizeof(unsigned long));
> | +
> | + BUILD_BUG_ON(offsetof(struct thread_struct, ppr) + sizeof(unsigned long)
> | + != offsetof(struct thread_struct, tar));
> | + /* TAR register */
> | + if (!ret)
> | + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | + &target->thread.tar, 2 * sizeof(unsigned long),
> | + 3 * sizeof(unsigned long));
> | + return ret;
> | +}
> | +
> | +static int misc_set(struct task_struct *target, const struct user_regset *regset,
> | + unsigned int pos, unsigned int count,
> | + const void *kbuf, const void __user *ubuf)
> | +{
> | + int ret;
> | +
> | + /* DSCR register */
> | + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | + &target->thread.dscr, 0,
> | + sizeof(unsigned long));
> | +
> | + BUILD_BUG_ON(offsetof(struct thread_struct, dscr) + sizeof(unsigned long) +
> | + sizeof(unsigned long) != offsetof(struct thread_struct, ppr));
> | +
> | + /* PPR register */
> | + if (!ret)
> | + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | + &target->thread.ppr, sizeof(unsigned long),
> | + 2 * sizeof(unsigned long));
> | +
> | + BUILD_BUG_ON(offsetof(struct thread_struct, ppr) + sizeof(unsigned long)
> | + != offsetof(struct thread_struct, tar));
> | +
> | + /* TAR register */
> | + if (!ret)
> | + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | + &target->thread.tar, 2 * sizeof(unsigned long),
> | + 3 * sizeof(unsigned long));
> | + return ret;
> | +}
> | +
> | +/*
> | * These are our native regset flavors.
> | */
> | enum powerpc_regset {
> | @@ -1169,6 +1239,7 @@ enum powerpc_regset {
> | REGSET_TM_CFPR, /* TM checkpointed FPR */
> | REGSET_TM_CVMX, /* TM checkpointed VMX */
> | #endif
> | + REGSET_MISC /* Miscellaneous */
> | };
> |
> | static const struct user_regset native_regsets[] = {
> | @@ -1225,6 +1296,11 @@ static const struct user_regset native_regsets[] = {
> | .active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
> | },
> | #endif
> | + [REGSET_MISC] = {
> | + .core_note_type = NT_PPC_MISC, .n = 3,
> | + .size = sizeof(u64), .align = sizeof(u64),
> | + .get = misc_get, .set = misc_set
> | + },
> | };
> |
> | static const struct user_regset_view user_ppc_native_view = {
> | @@ -1566,6 +1642,11 @@ static const struct user_regset compat_regsets[] = {
> | .active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
> | },
> | #endif
> | + [REGSET_MISC] = {
> | + .core_note_type = NT_PPC_MISC, .n = 3,
> | + .size = sizeof(u64), .align = sizeof(u64),
> | + .get = misc_get, .set = misc_set
> | + },
>
> Since the .n = 3 is used more than once, how about a macro for the
> number of misc registers ?
Will add it as well. Thanks !
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