Re: [PATCH v3 09/19] unwind: Introduce sframe user space unwinding
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2024-11-13 22:21:01
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[ This reply fixes the linux-trace-kernel email :-p ] On Wed, 13 Nov 2024 17:13:26 -0500 Steven Rostedt [off-list ref] wrote:
quoted hunk
BTW, the following changes were needed to make it work for me: -- Stevediff --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.
quoted hunk
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.
quoted hunk
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.
quoted hunk
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
} /*