[ This reply fixes the linux-trace-kernel email :-p ]

On Wed, 13 Nov 2024 17:13:26 -0500
Steven Rostedt <[email protected]> wrote:

> BTW, the following changes were needed to make it work for me:
> 
> -- Steve
> 
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index 434c548f0837..64cc3c1188ca 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -842,7 +842,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
>       int first_pt_load = 1;
>       unsigned long error;
>       struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL;
> -     struct elf_phdr *elf_property_phdata = NULL, *sframe_phdr = NULL;
> +     struct elf_phdr *elf_property_phdata = NULL;
> +     unsigned long sframe_vaddr = 0;

Could not just save the pointer to the sframe phd, as it gets freed before we 
need it.

>       unsigned long elf_brk;
>       int retval, i;
>       unsigned long elf_entry;
> @@ -951,7 +952,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
>                       break;
>  
>               case PT_GNU_SFRAME:
> -                     sframe_phdr = elf_ppnt;
> +                     sframe_vaddr = elf_ppnt->p_vaddr;
>                       break;
>  
>               case PT_LOPROC ... PT_HIPROC:
> @@ -1344,8 +1345,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
>                                           task_pid_nr(current), retval);
>       }
>  
> -     if (sframe_phdr)
> -             sframe_add_section(load_bias + sframe_phdr->p_vaddr,
> +     if (sframe_vaddr)
> +             sframe_add_section(load_bias + sframe_vaddr,
>                                  start_code, end_code);
>  
>       regs = current_pt_regs();
> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
> index 933e47696e29..ca4ef0b72772 100644
> --- a/kernel/unwind/sframe.c
> +++ b/kernel/unwind/sframe.c
> @@ -73,15 +73,15 @@ static int find_fde(struct sframe_section *sec, unsigned 
> long ip,
>                   struct sframe_fde *fde)
>  {
>       struct sframe_fde __user *first, *last, *found = NULL;
> -     u32 ip_off, func_off_low = 0, func_off_high = -1;
> +     s32 ip_off, func_off_low = INT_MIN, func_off_high = INT_MAX;

The ip_off is a signed it. I wrote a program to dump out the sframe section
of files, and I had:

        ffffed88: (1020) size:      16 off:     146 num:       2 info: 1 rep:16
        ffffed98: (1030) size:     336 off:     154 num:       2 info:17 rep:16
        ffffefe1: (1279) size:     113 off:       0 num:       4 info: 0 rep: 0
        fffff052: (12ea) size:      54 off:      15 num:       3 info: 0 rep: 0
        fffff088: (1320) size:     167 off:      26 num:       3 info: 0 rep: 0
        fffff12f: (13c7) size:     167 off:      37 num:       4 info: 0 rep: 0
        fffff1d6: (146e) size:     167 off:      52 num:       4 info: 0 rep: 0
        fffff27d: (1515) size:      22 off:      67 num:       4 info: 0 rep: 0
        fffff293: (152b) size:     141 off:      82 num:       4 info: 0 rep: 0
        fffff320: (15b8) size:      81 off:      97 num:       4 info: 0 rep: 0
        fffff371: (1609) size:     671 off:     112 num:       4 info: 1 rep: 0
        fffff610: (18a8) size:     171 off:     131 num:       4 info: 0 rep: 0

The above turns was created by a loop of:

        fde = (void *)sframes + sizeof(*sframes) + sframes->sfh_fdeoff;
        for (s = 0; s < sframes->sfh_num_fdes; s++, fde++) {
                printf("\t%x: (%lx) size:%8u off:%8u num:%8u info:%2u 
rep:%2u\n",
                       fde->sfde_func_start_address,
                       fde->sfde_func_start_address + shdr->sh_offset,
                       fde->sfde_func_size,
                       fde->sfde_func_start_fre_off,
                       fde->sfde_func_num_fres,
                       fde->sfde_func_info,
                       fde->sfde_func_rep_size);
        }

As you can see, all the ip_off are negative.

>  
>       ip_off = ip - sec->sframe_addr;
>  
>       first = (void __user *)sec->fdes_addr;
> -     last = first + sec->fdes_nr;
> +     last = first + sec->fdes_nr - 1;

The above was mentioned before.

>       while (first <= last) {
>               struct sframe_fde __user *mid;
> -             u32 func_off;
> +             s32 func_off;
>  
>               mid = first + ((last - first) / 2);
>  
> diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
> index 11aadfade005..d9cd820150c5 100644
> --- a/kernel/unwind/user.c
> +++ b/kernel/unwind/user.c
> @@ -97,7 +97,7 @@ int unwind_user_start(struct unwind_user_state *state)
>  
>       if (current_has_sframe())
>               state->type = UNWIND_USER_TYPE_SFRAME;
> -     else if (IS_ENABLED(CONFIG_UNWIND_USER_FP))
> +     else if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))

This was mentioned too.

>               state->type = UNWIND_USER_TYPE_FP;
>       else
>               state->type = UNWIND_USER_TYPE_NONE;
> @@ -138,7 +138,7 @@ int unwind_user(struct unwind_stacktrace *trace, unsigned 
> int max_entries)
>  static u64 ctx_to_cookie(u64 cpu, u64 ctx)
>  {
>       BUILD_BUG_ON(NR_CPUS > 65535);
> -     return (ctx & ((1UL << 48) - 1)) | cpu;
> +     return (ctx & ((1UL << 48) - 1)) | (cpu << 48);

And so was this.

-- Steve

>  }
>  
>  /*


Reply via email to