Re: [PATCH 16/23] arm64: ilp32: introduce binfmt_ilp32.c

From: Yury Norov
Date: Tue Jun 14 2016 - 20:40:45 EST

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In reply to: Zhangjian (Bamvor): "Re: [PATCH 16/23] arm64: ilp32: introduce binfmt_ilp32.c"
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On Thu, May 26, 2016 at 09:49:42PM +0800, Zhangjian (Bamvor) wrote:
> Hi, yury
>
> The coredump is usable in our platform. It miss the following definition:
> +#define compat_elf_greg_t elf_greg_t
> +#define compat_elf_gregset_t elf_gregset_t
>
> And it leads to the wrong register save in core dump. After apply this patch,
> gdb could debug core dump files.
>
> Here is the full patch:
> From 102624840aa5dacdd1bbfe3b390290f52f530ea2 Mon Sep 17 00:00:00 2001
> From: Bamvor Jian Zhang <bamvor.zhangjian@xxxxxxxxxx>
> Date: Thu, 26 May 2016 21:00:16 +0800
> Subject: [PATCH hulk-4.1-next] arm64: ilp32: fix coredump issue
>
> ILP32 use aarch64 register and 32bit signal struct which means it
> could not make use of the existing compat_elf_prstatus/elf_prstatus
> and compat_elf_prpsinfo/elf_prpsinfo.
>
> This patch fix this issue by introducing the different
> compat_elf_greg_t, compat_elf_gregset_t for aarch64 ilp32 and aarch32
> el0.
>
> Tested pass on huawei's hardware in bigendian.
>
> Signed-off-by: Bamvor Jian Zhang <bamvor.zhangjian@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/elf.h | 14 +++++++-------
> arch/arm64/kernel/binfmt_elf32.c | 3 +++
> arch/arm64/kernel/binfmt_ilp32.c | 8 +++++++-
> arch/arm64/kernel/ptrace.c | 20 ++++++++++----------
> 4 files changed, 27 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
> index 0106d18..9019441 100644
> --- a/arch/arm64/include/asm/elf.h
> +++ b/arch/arm64/include/asm/elf.h
> @@ -154,18 +154,18 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
> int uses_interp);
>
> /* 1GB of VA */
> -#define STACK_RND_MASK (is_compat_task() ? \
> - 0x7ff >> (PAGE_SHIFT - 12) : \
> - 0x3ffff >> (PAGE_SHIFT - 12))
> +#define STACK_RND_MASK (is_compat_task() ? \
> + 0x7ff >> (PAGE_SHIFT - 12) : \
> + 0x3ffff >> (PAGE_SHIFT - 12))
>
> #ifdef CONFIG_COMPAT
>
> -#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3)
> +#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3)
>
> /* AArch32 registers. */
> -#define COMPAT_ELF_NGREG 18
> -typedef unsigned int compat_elf_greg_t;
> -typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG];
> +#define COMPAT_ELF_NGREG 18
> +typedef unsigned int compat_a32_elf_greg_t;
> +typedef compat_a32_elf_greg_t compat_a32_elf_gregset_t[COMPAT_ELF_NGREG];
>
> #endif /* CONFIG_COMPAT */
>
> diff --git a/arch/arm64/kernel/binfmt_elf32.c b/arch/arm64/kernel/binfmt_elf32.c
> index 7b9b445..f75253c 100644
> --- a/arch/arm64/kernel/binfmt_elf32.c
> +++ b/arch/arm64/kernel/binfmt_elf32.c
> @@ -31,4 +31,7 @@ struct linux_binprm;
> extern int aarch32_setup_vectors_page(struct linux_binprm *bprm,
> int uses_interp);
>
> +#define compat_elf_greg_t compat_a32_elf_greg_t
> +#define compat_elf_gregset_t compat_a32_elf_gregset_t
> +
> #include "../../../fs/compat_binfmt_elf.c"
> diff --git a/arch/arm64/kernel/binfmt_ilp32.c b/arch/arm64/kernel/binfmt_ilp32.c
> index b827a9a..01baf83 100644
> --- a/arch/arm64/kernel/binfmt_ilp32.c
> +++ b/arch/arm64/kernel/binfmt_ilp32.c
> @@ -2,7 +2,9 @@
> * Support for ILP32 Linux/aarch64 ELF binaries.
> */
>
> -#include <linux/elfcore-compat.h>
> +#include <linux/elf.h>
> +#include <linux/elfcore.h>
> +#include <linux/compat.h>
> #include <linux/time.h>
>
> #undef ELF_CLASS
> @@ -30,9 +32,13 @@
> * The machine-dependent core note format types are defined in elfcore-compat.h,
> * which requires asm/elf.h to define compat_elf_gregset_t et al.
> */
> +#define compat_elf_greg_t elf_greg_t
> +#define compat_elf_gregset_t elf_gregset_t
> #define elf_prstatus compat_elf_prstatus
> #define elf_prpsinfo compat_elf_prpsinfo
>
> +#include <linux/elfcore-compat.h>
> +
> /*
> * Compat version of cputime_to_compat_timeval, perhaps this
> * should be an inline in <linux/compat.h>.
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 5c86135..9784c77 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -913,8 +913,8 @@ static const struct user_regset aarch32_regsets[] = {
> [REGSET_COMPAT_GPR] = {
> .core_note_type = NT_PRSTATUS,
> .n = COMPAT_ELF_NGREG,
> - .size = sizeof(compat_elf_greg_t),
> - .align = sizeof(compat_elf_greg_t),
> + .size = sizeof(compat_a32_elf_greg_t),
> + .align = sizeof(compat_a32_elf_greg_t),
> .get = compat_gpr_get,
> .set = compat_gpr_set
> },
> @@ -947,7 +947,7 @@ static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,
> tmp = tsk->mm->start_data;
> else if (off == COMPAT_PT_TEXT_END_ADDR)
> tmp = tsk->mm->end_code;
> - else if (off < sizeof(compat_elf_gregset_t))
> + else if (off < sizeof(compat_a32_elf_gregset_t))
> return copy_regset_to_user(tsk, &user_aarch32_view,
> REGSET_COMPAT_GPR, off,
> sizeof(compat_ulong_t), ret);
> @@ -968,7 +968,7 @@ static int compat_ptrace_write_user(struct task_struct *tsk, compat_ulong_t off,
> if (off & 3 || off >= COMPAT_USER_SZ)
> return -EIO;
>
> - if (off >= sizeof(compat_elf_gregset_t))
> + if (off >= sizeof(compat_a32_elf_gregset_t))
> return 0;
>
> set_fs(KERNEL_DS);
> @@ -1116,9 +1116,11 @@ static long compat_a32_ptrace(struct task_struct *child, compat_long_t request,
> unsigned long addr = caddr;
> unsigned long data = cdata;
> void __user *datap = compat_ptr(data);
> + unsigned int pr_reg_size = sizeof(compat_a32_elf_gregset_t);
> int ret;
>
> switch (request) {
> +
> case PTRACE_PEEKUSR:
> ret = compat_ptrace_read_user(child, addr, datap);
> break;
> @@ -1130,17 +1132,15 @@ static long compat_a32_ptrace(struct task_struct *child, compat_long_t request,
> case COMPAT_PTRACE_GETREGS:
> ret = copy_regset_to_user(child,
> &user_aarch32_view,
> - REGSET_COMPAT_GPR,
> - 0, sizeof(compat_elf_gregset_t),
> - datap);
> + REGSET_COMPAT_GPR, 0,
> + pr_reg_size, datap);
> break;
>
> case COMPAT_PTRACE_SETREGS:
> ret = copy_regset_from_user(child,
> &user_aarch32_view,
> - REGSET_COMPAT_GPR,
> - 0, sizeof(compat_elf_gregset_t),
> - datap);
> + REGSET_COMPAT_GPR, 0,
> + pr_reg_size, datap);
> break;
>
> case COMPAT_PTRACE_GET_THREAD_AREA:

Hi Bamvor,

I didn't work much with ilp32 debugging and coredumps yet, but what I
see in your patch is an attempt to use elf_gregset_t in compat_elf_prstatus
for ilp32 instead of compat_elf_gregset_t.

I think we can do it simpler. That's what pahole shows for binfmt_ilp32.o
after applying the attached patch:

struct compat_elf_prstatus {
struct compat_elf_siginfo pr_info; /* 0 12 */
short int pr_cursig; /* 12 2 */

/* XXX 2 bytes hole, try to pack */

compat_ulong_t pr_sigpend; /* 16 4 */
compat_ulong_t pr_sighold; /* 20 4 */
compat_pid_t pr_pid; /* 24 4 */
compat_pid_t pr_ppid; /* 28 4 */
compat_pid_t pr_pgrp; /* 32 4 */
compat_pid_t pr_sid; /* 36 4 */
struct compat_timeval pr_utime; /* 40 8 */
struct compat_timeval pr_stime; /* 48 8 */
struct compat_timeval pr_cutime; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct compat_timeval pr_cstime; /* 64 8 */
elf_gregset_t pr_reg; /* 72 272 */
/* --- cacheline 5 boundary (320 bytes) was 24 bytes ago --- */
compat_int_t pr_fpvalid; /* 344 4 */

/* size: 352, cachelines: 6, members: 14 */
/* sum members: 346, holes: 1, sum holes: 2 */
/* padding: 4 */
/* last cacheline: 32 bytes */
};

Did I miss something?
---
arch/arm64/include/asm/elf.h | 6 ++++++
arch/arm64/kernel/binfmt_ilp32.c | 1 +
2 files changed, 7 insertions(+)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index a967726..4dcbcec 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -174,10 +174,16 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,

#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3)

+#ifndef USE_AARCH64_GREG
/* AArch32 registers. */
#define COMPAT_ELF_NGREG 18
typedef unsigned int compat_elf_greg_t;
typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG];
+#else /* AArch64 registers for AARCH64/ILP32 */
+#define COMPAT_ELF_NGREG ELF_NGREG
+#define compat_elf_greg_t elf_greg_t
+#define compat_elf_gregset_t elf_gregset_t
+#endif

/* AArch32 EABI. */
#define EF_ARM_EABI_MASK 0xff000000
diff --git a/arch/arm64/kernel/binfmt_ilp32.c b/arch/arm64/kernel/binfmt_ilp32.c
index b2bd590..416b3f5 100644
--- a/arch/arm64/kernel/binfmt_ilp32.c
+++ b/arch/arm64/kernel/binfmt_ilp32.c
@@ -1,6 +1,7 @@
/*
* Support for ILP32 Linux/aarch64 ELF binaries.
*/
+#define USE_AARCH64_GREG

#include <linux/elfcore-compat.h>
#include <linux/time.h>
--
2.7.4

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In reply to: Zhangjian (Bamvor): "Re: [PATCH 16/23] arm64: ilp32: introduce binfmt_ilp32.c"
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