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Message-ID: <1f83be89-b816-48a3-a7ee-9b72f07b558e@linux.ibm.com>
Date: Thu, 7 Nov 2024 17:59:08 +0100
From: Jens Remus <jremus@...ux.ibm.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-kernel@...r.kernel.org, Indu Bhagat <indu.bhagat@...cle.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org, Mark Brown <broonie@...nel.org>,
linux-toolchains@...r.kernel.org, Jordan Rome <jordalgo@...a.com>,
Sam James <sam@...too.org>, linux-trace-kernel@...r.kerne.org,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Florian Weimer <fweimer@...hat.com>, Andy Lutomirski <luto@...nel.org>,
Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH v3 09/19] unwind: Introduce sframe user space unwinding
On 28.10.2024 22:47, Josh Poimboeuf wrote:
...
> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
...
> +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;
> +
> + ip_off = ip - sec->sframe_addr;
> +
> + first = (void __user *)sec->fdes_addr;
> + last = first + sec->fdes_nr;
Could it be that this needs to be:
last = first + sec->fdes_nr - 1;
> + while (first <= last) {
> + struct sframe_fde __user *mid;
> + u32 func_off;
> +
> + mid = first + ((last - first) / 2);
> +
> + if (get_user(func_off, (s32 __user *)mid))
> + return -EFAULT;
> +
> + if (ip_off >= func_off) {
> + /* validate sort order */
> + if (func_off < func_off_low)
> + return -EINVAL;
Otherwise I run into this when the IP is within the function whose FDE
is the last one in the .sframe section:
find_fde: IP=0x000000000110fbcc: ERROR: func_off < func_off_low
(func_off=196608, func_off_low=4294224904)
110fbcc dump_sframe+0x2ec (/opt/binutils-sframe2/bin/objdump)
func idx [2275]: pc = 0x110f8e0, size = 3310 bytes <dump_sframe>
STARTPC CFA FP RA INFO
000000000110f8e0 sp+160 u u (1*1B)
000000000110f8e6 sp+160 c-72 c-48 (3*1B)
000000000110f8f6 sp+632 c-72 c-48 (3*1B)
000000000110fa82 sp+160 u u (1*1B)
000000000110fa88 sp+632 c-72 c-48 (3*1B)
0000000001110486 sp+160 u u (1*1B)
000000000111048c sp+632 c-72 c-48 (3*1B)
0000000001110574 sp+160 u u (1*1B)
000000000111057a sp+632 c-72 c-48 (3*1B)
> +
> + func_off_low = func_off;
> +
> + found = mid;
> + first = mid + 1;
> + } else {
> + /* validate sort order */
> + if (func_off > func_off_high)
> + return -EINVAL;
> +
> + func_off_high = func_off;
> +
> + last = mid - 1;
> + }
> + }
> +
> + if (!found)
> + return -EINVAL;
> +
> + if (copy_from_user(fde, found, sizeof(*fde)))
> + return -EFAULT;
> +
> + /* check for gaps */
> + if (ip_off < fde->start_addr || ip_off >= fde->start_addr + fde->size)
> + return -EINVAL;
> +
> + return 0;
> +}
Thanks and regards,
Jens
--
Jens Remus
Linux on Z Development (D3303) and z/VSE Support
+49-7031-16-1128 Office
jremus@...ibm.com
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