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Message-Id: <1649458366-25288-2-git-send-email-alan.maguire@oracle.com>
Date: Fri, 8 Apr 2022 23:52:45 +0100
From: Alan Maguire <alan.maguire@...cle.com>
To: andrii@...nel.org, iii@...ux.ibm.com, ast@...nel.org,
daniel@...earbox.net
Cc: kafai@...com, songliubraving@...com, yhs@...com,
john.fastabend@...il.com, kpsingh@...nel.org,
netdev@...r.kernel.org, bpf@...r.kernel.org,
Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH bpf-next 1/2] libbpf: usdt: factor out common USDT arg handling
Common code to initialize a struct usdt_arg_spec can be factored out
from arch-specific flavours of parse_usdt_arg(); signed size,
bitshift handling etc.
Signed-off-by: Alan Maguire <alan.maguire@...cle.com>
---
tools/lib/bpf/usdt.c | 90 ++++++++++++++++++++++++----------------------------
1 file changed, 41 insertions(+), 49 deletions(-)
diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
index 30c495a..0677bbd 100644
--- a/tools/lib/bpf/usdt.c
+++ b/tools/lib/bpf/usdt.c
@@ -1170,6 +1170,31 @@ static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note,
/* Architecture-specific logic for parsing USDT argument location specs */
+#if defined(__x86_64__) || defined(__i386__) || defined(__s390x__)
+
+static int init_usdt_arg_spec(struct usdt_arg_spec *arg, enum usdt_arg_type arg_type, int arg_sz,
+ __u64 val_off, int reg_off)
+{
+ if (reg_off < 0)
+ return reg_off;
+ arg->arg_type = arg_type;
+ arg->val_off = val_off;
+ arg->reg_off = reg_off;
+ arg->arg_signed = arg_sz < 0;
+ if (arg_sz < 0)
+ arg_sz = -arg_sz;
+
+ switch (arg_sz) {
+ case 1: case 2: case 4: case 8:
+ arg->arg_bitshift = 64 - arg_sz * 8;
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+#endif
+
#if defined(__x86_64__) || defined(__i386__)
static int calc_pt_regs_off(const char *reg_name)
@@ -1220,52 +1245,32 @@ static int calc_pt_regs_off(const char *reg_name)
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
{
char *reg_name = NULL;
- int arg_sz, len, reg_off;
+ int arg_sz, len, ret;
long off;
if (sscanf(arg_str, " %d @ %ld ( %%%m[^)] ) %n", &arg_sz, &off, ®_name, &len) == 3) {
/* Memory dereference case, e.g., -4@-20(%rbp) */
- arg->arg_type = USDT_ARG_REG_DEREF;
- arg->val_off = off;
- reg_off = calc_pt_regs_off(reg_name);
+ ret = init_usdt_arg_spec(arg, USDT_ARG_REG_DEREF, arg_sz, off,
+ calc_pt_regs_off(reg_name));
free(reg_name);
- if (reg_off < 0)
- return reg_off;
- arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ %%%ms %n", &arg_sz, ®_name, &len) == 2) {
/* Register read case, e.g., -4@...x */
- arg->arg_type = USDT_ARG_REG;
- arg->val_off = 0;
-
- reg_off = calc_pt_regs_off(reg_name);
+ ret = init_usdt_arg_spec(arg, USDT_ARG_REG, arg_sz, 0,
+ calc_pt_regs_off(reg_name));
free(reg_name);
- if (reg_off < 0)
- return reg_off;
- arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ $%ld %n", &arg_sz, &off, &len) == 2) {
/* Constant value case, e.g., 4@$71 */
- arg->arg_type = USDT_ARG_CONST;
- arg->val_off = off;
- arg->reg_off = 0;
+ ret = init_usdt_arg_spec(arg, USDT_ARG_CONST, arg_sz, off, 0);
} else {
pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
return -EINVAL;
}
- arg->arg_signed = arg_sz < 0;
- if (arg_sz < 0)
- arg_sz = -arg_sz;
-
- switch (arg_sz) {
- case 1: case 2: case 4: case 8:
- arg->arg_bitshift = 64 - arg_sz * 8;
- break;
- default:
+ if (ret < 0) {
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
arg_num, arg_str, arg_sz);
- return -EINVAL;
+ return ret;
}
-
return len;
}
@@ -1276,51 +1281,38 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg)
{
unsigned int reg;
- int arg_sz, len;
+ int arg_sz, len, ret;
long off;
if (sscanf(arg_str, " %d @ %ld ( %%r%u ) %n", &arg_sz, &off, ®, &len) == 3) {
/* Memory dereference case, e.g., -2@-28(%r15) */
- arg->arg_type = USDT_ARG_REG_DEREF;
- arg->val_off = off;
if (reg > 15) {
pr_warn("usdt: unrecognized register '%%r%u'\n", reg);
return -EINVAL;
}
- arg->reg_off = offsetof(user_pt_regs, gprs[reg]);
+ ret = init_usdt_arg_spec(arg, USDT_ARG_REG_DEREF, arg_sz, off,
+ offsetof(user_pt_regs, gprs[reg]));
} else if (sscanf(arg_str, " %d @ %%r%u %n", &arg_sz, ®, &len) == 2) {
/* Register read case, e.g., -8@%r0 */
- arg->arg_type = USDT_ARG_REG;
- arg->val_off = 0;
if (reg > 15) {
pr_warn("usdt: unrecognized register '%%r%u'\n", reg);
return -EINVAL;
}
- arg->reg_off = offsetof(user_pt_regs, gprs[reg]);
+ ret = init_usdt_arg_spec(arg, USDT_ARG_REG, arg_sz, 0,
+ offsetof(user_pt_regs, gprs[reg]));
} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {
/* Constant value case, e.g., 4@71 */
- arg->arg_type = USDT_ARG_CONST;
- arg->val_off = off;
- arg->reg_off = 0;
+ ret = init_usdt_arg_spec(arg, USDT_ARG_CONST, arg_sz, off, 0);
} else {
pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);
return -EINVAL;
}
- arg->arg_signed = arg_sz < 0;
- if (arg_sz < 0)
- arg_sz = -arg_sz;
-
- switch (arg_sz) {
- case 1: case 2: case 4: case 8:
- arg->arg_bitshift = 64 - arg_sz * 8;
- break;
- default:
+ if (ret < 0) {
pr_warn("usdt: unsupported arg #%d (spec '%s') size: %d\n",
arg_num, arg_str, arg_sz);
- return -EINVAL;
+ return ret;
}
-
return len;
}
--
1.8.3.1
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