Re: [PATCH V2 11/17] riscv: compat: Add elf.h implementation
On Mon, Jan 10, 2022 at 10:29 PM Arnd Bergmann wrote:
>
> On Tue, Dec 28, 2021 at 3:39 PM wrote:
> >
> > From: Guo Ren
> >
> > Implement necessary type and macro for compat elf. See the code
> > comment for detail.
> >
> > Signed-off-by: Guo Ren
> > Signed-off-by: Guo Ren
> > Cc: Arnd Bergmann
>
> This looks mostly correct,
>
> > +/*
> > + * FIXME: not sure SET_PERSONALITY for compat process is right!
> > + */
> > +#define SET_PERSONALITY(ex) \
> > +do {if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
> > + set_thread_flag(TIF_32BIT);\
> > + else \
> > + clear_thread_flag(TIF_32BIT); \
> > + set_personality(PER_LINUX | (current->personality & (~PER_MASK))); \
> > +} while (0)
>
> This means the personality after exec is always set to PER_LINUX, not
> PER_LINUX32, which I think is wrong: you want the PER_LINUX32
> setting to stick, just like the upper bits do in the default implementation.
>
> What the other ones do is:
>
> | arch/parisc/include/asm/elf.h-
> set_personality((current->personality & ~PER_MASK) | PER_LINUX); \
>
> This looks like the same problem you introduce here: always forcing PER_LINUX
> instead of PER_LINUX32 makes it impossible to use PER_LINUX32.
>
> | arch/alpha/include/asm/elf.h:#define SET_PERSONALITY(EX)
>\
> | arch/alpha/include/asm/elf.h- set_personality(((EX).e_flags &
> EF_ALPHA_32BIT) \
> | arch/alpha/include/asm/elf.h- ? PER_LINUX_32BIT : PER_LINUX)
> | arch/csky/include/asm/elf.h:#define SET_PERSONALITY(ex)
> set_personality(PER_LINUX)
> | arch/nds32/include/asm/elf.h:#define SET_PERSONALITY(ex)
> set_personality(PER_LINUX)
>
> These look even worse: instead of forcing the lower bits to
> PER_LINUX/PER_LINUX32 and
> leaving the upper bits untouched, these also clear the upper bits
> unconditionally.
>
> | arch/arm64/include/asm/elf.h:#define SET_PERSONALITY(ex)
>\
> | arch/arm64/include/asm/elf.h- current->personality &=
> ~READ_IMPLIES_EXEC; \
> | arch/x86/um/asm/elf.h:#define SET_PERSONALITY(ex) do {} while(0)
> | arch/x86/include/asm/elf.h:#define set_personality_64bit() do {
> } while (0)
> | arch/x86/kernel/process_64.c:static void __set_personality_ia32(void)
> | current->personality |= force_personality32;
>
> Inconsistent: does not enforce PER_LINUX/PER_LINUX32 as the default
> implementation
> does, but just leaves the value untouched (other than (re)setting
> READ_IMPLIES_EXEC).
> I think this is harmless otherwise, as we generally ignore the lower
> bits, except for the
> bit of code that checks for PER_LINUX32 in override_architecture() to mangle
> the
> output of sys_newuname() or in /proc/cpuinfo.
>
> | arch/s390/include/asm/elf.h-if
> (personality(current->personality) != PER_LINUX32) \
> | arch/s390/include/asm/elf.h-set_personality(PER_LINUX |
>\
> | arch/s390/include/asm/elf.h-
> (current->personality & ~PER_MASK));\
> | arch/powerpc/include/asm/elf.h- if
> (personality(current->personality) != PER_LINUX32) \
> | arch/powerpc/include/asm/elf.h- set_personality(PER_LINUX |
>\
> | arch/powerpc/include/asm/elf.h-
> (current->personality & (~PER_MASK))); \
> | arch/sparc/include/asm/elf_64.h-if
> (personality(current->personality) != PER_LINUX32) \
> | arch/sparc/include/asm/elf_64.h-
> set_personality(PER_LINUX | \
> | arch/sparc/include/asm/elf_64.h-
> (current->personality & (~PER_MASK))); \
>
> This is probably the behavior you want to copy.
Thank you very much for your detailed explanation. Here is my modification.
+#define SET_PERSONALITY(ex)\
+do {if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
+ set_thread_flag(TIF_32BIT); \
+ else\
+ clear_thread_flag(TIF_32BIT); \
+ if (personality(current->personality) != PER_LINUX32) \
+ set_personality(PER_LINUX | \
+ (current->personality & (~PER_MASK))); \
+} while (0)
>
> Arnd
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
Re: [PATCH V2 11/17] riscv: compat: Add elf.h implementation
On Tue, Dec 28, 2021 at 3:39 PM wrote:
>
> From: Guo Ren
>
> Implement necessary type and macro for compat elf. See the code
> comment for detail.
>
> Signed-off-by: Guo Ren
> Signed-off-by: Guo Ren
> Cc: Arnd Bergmann
This looks mostly correct,
> +/*
> + * FIXME: not sure SET_PERSONALITY for compat process is right!
> + */
> +#define SET_PERSONALITY(ex) \
> +do {if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
> + set_thread_flag(TIF_32BIT);\
> + else \
> + clear_thread_flag(TIF_32BIT); \
> + set_personality(PER_LINUX | (current->personality & (~PER_MASK))); \
> +} while (0)
This means the personality after exec is always set to PER_LINUX, not
PER_LINUX32, which I think is wrong: you want the PER_LINUX32
setting to stick, just like the upper bits do in the default implementation.
What the other ones do is:
| arch/parisc/include/asm/elf.h-
set_personality((current->personality & ~PER_MASK) | PER_LINUX); \
This looks like the same problem you introduce here: always forcing PER_LINUX
instead of PER_LINUX32 makes it impossible to use PER_LINUX32.
| arch/alpha/include/asm/elf.h:#define SET_PERSONALITY(EX)
\
| arch/alpha/include/asm/elf.h- set_personality(((EX).e_flags &
EF_ALPHA_32BIT) \
| arch/alpha/include/asm/elf.h- ? PER_LINUX_32BIT : PER_LINUX)
| arch/csky/include/asm/elf.h:#define SET_PERSONALITY(ex)
set_personality(PER_LINUX)
| arch/nds32/include/asm/elf.h:#define SET_PERSONALITY(ex)
set_personality(PER_LINUX)
These look even worse: instead of forcing the lower bits to
PER_LINUX/PER_LINUX32 and
leaving the upper bits untouched, these also clear the upper bits
unconditionally.
| arch/arm64/include/asm/elf.h:#define SET_PERSONALITY(ex)
\
| arch/arm64/include/asm/elf.h- current->personality &=
~READ_IMPLIES_EXEC; \
| arch/x86/um/asm/elf.h:#define SET_PERSONALITY(ex) do {} while(0)
| arch/x86/include/asm/elf.h:#define set_personality_64bit() do {
} while (0)
| arch/x86/kernel/process_64.c:static void __set_personality_ia32(void)
| current->personality |= force_personality32;
Inconsistent: does not enforce PER_LINUX/PER_LINUX32 as the default
implementation
does, but just leaves the value untouched (other than (re)setting
READ_IMPLIES_EXEC).
I think this is harmless otherwise, as we generally ignore the lower
bits, except for the
bit of code that checks for PER_LINUX32 in override_architecture() to mangle the
output of sys_newuname() or in /proc/cpuinfo.
| arch/s390/include/asm/elf.h-if
(personality(current->personality) != PER_LINUX32) \
| arch/s390/include/asm/elf.h-set_personality(PER_LINUX |
\
| arch/s390/include/asm/elf.h-
(current->personality & ~PER_MASK));\
| arch/powerpc/include/asm/elf.h- if
(personality(current->personality) != PER_LINUX32) \
| arch/powerpc/include/asm/elf.h- set_personality(PER_LINUX |
\
| arch/powerpc/include/asm/elf.h-
(current->personality & (~PER_MASK))); \
| arch/sparc/include/asm/elf_64.h-if
(personality(current->personality) != PER_LINUX32) \
| arch/sparc/include/asm/elf_64.h-
set_personality(PER_LINUX | \
| arch/sparc/include/asm/elf_64.h-
(current->personality & (~PER_MASK))); \
This is probably the behavior you want to copy.
Arnd
[PATCH V2 11/17] riscv: compat: Add elf.h implementation
From: Guo Ren
Implement necessary type and macro for compat elf. See the code
comment for detail.
Signed-off-by: Guo Ren
Signed-off-by: Guo Ren
Cc: Arnd Bergmann
---
arch/riscv/include/asm/elf.h | 49 +++-
1 file changed, 48 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index f53c40026c7a..91b372d4e13b 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h
@@ -8,6 +8,8 @@
#ifndef _ASM_RISCV_ELF_H
#define _ASM_RISCV_ELF_H
+#include
+#include
#include
#include
#include
@@ -18,11 +20,13 @@
*/
#define ELF_ARCH EM_RISCV
+#ifndef ELF_CLASS
#ifdef CONFIG_64BIT
#define ELF_CLASS ELFCLASS64
#else
#define ELF_CLASS ELFCLASS32
#endif
+#endif
#define ELF_DATA ELFDATA2LSB
@@ -31,6 +35,15 @@
*/
#define elf_check_arch(x) ((x)->e_machine == EM_RISCV)
+#ifdef CONFIG_COMPAT
+/*
+ * Use the same code with elf_check_arch, because elf32_hdr &
+ * elf64_hdr e_machine's offset are different. The checker is
+ * a little bit simple compare to other architectures.
+ */
+#define compat_elf_check_arch(x) ((x)->e_machine == EM_RISCV)
+#endif
+
#define CORE_DUMP_USE_REGSET
#define ELF_EXEC_PAGESIZE (PAGE_SIZE)
@@ -43,8 +56,14 @@
#define ELF_ET_DYN_BASE((TASK_SIZE / 3) * 2)
#ifdef CONFIG_64BIT
+#ifdef CONFIG_COMPAT
+#define STACK_RND_MASK (test_thread_flag(TIF_32BIT) ? \
+0x7ff >> (PAGE_SHIFT - 12) : \
+0x3 >> (PAGE_SHIFT - 12))
+#else
#define STACK_RND_MASK (0x3 >> (PAGE_SHIFT - 12))
#endif
+#endif
/*
* This yields a mask that user programs can use to figure out what
* instruction set this CPU supports. This could be done in user space,
@@ -60,11 +79,19 @@ extern unsigned long elf_hwcap;
*/
#define ELF_PLATFORM (NULL)
+#define COMPAT_ELF_PLATFORM(NULL)
+
#ifdef CONFIG_MMU
#define ARCH_DLINFO\
do { \
+ /* \
+* Note that we add ulong after elf_addr_t because \
+* casting current->mm->context.vdso triggers a cast\
+* warning of cast from pointer to integer for \
+* COMPAT ELFCLASS32. \
+*/ \
NEW_AUX_ENT(AT_SYSINFO_EHDR,\
- (elf_addr_t)current->mm->context.vdso); \
+ (elf_addr_t)(ulong)current->mm->context.vdso); \
NEW_AUX_ENT(AT_L1I_CACHESIZE, \
get_cache_size(1, CACHE_TYPE_INST));\
NEW_AUX_ENT(AT_L1I_CACHEGEOMETRY, \
@@ -90,4 +117,24 @@ do {
\
*(struct user_regs_struct *)regs; \
} while (0);
+#ifdef CONFIG_COMPAT
+
+/*
+ * FIXME: not sure SET_PERSONALITY for compat process is right!
+ */
+#define SET_PERSONALITY(ex) \
+do {if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
+ set_thread_flag(TIF_32BIT);\
+ else \
+ clear_thread_flag(TIF_32BIT); \
+ set_personality(PER_LINUX | (current->personality & (~PER_MASK))); \
+} while (0)
+
+#define COMPAT_ELF_ET_DYN_BASE ((TASK_SIZE_32 / 3) * 2)
+
+/* rv32 registers */
+typedef compat_ulong_t compat_elf_greg_t;
+typedef compat_elf_greg_t compat_elf_gregset_t[ELF_NGREG];
+
+#endif /* CONFIG_COMPAT */
#endif /* _ASM_RISCV_ELF_H */
--
2.25.1
